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The Dynamic Duo Share Ideas on How to Teach Chemistry
Eva Lou Apel &
Barbara Schumann
1
The Dynamic Duo
The Dynamic Duo Shares Ideas on How to Teach Chemistry Eva Lou Apel and Barbara Schumann
First Edition November 2007 Austin, Texas
© 2007 Eva Lou Apel & Barbara Schumann
This work is licensed under a Creative Commons License—Attribution. You may copy, distribute, display, and use this copyrighted work — and derivative works based upon it — but only if you give credit to The Dynamic Duo Shares ideas on How to Teach Chemistry, First Edition, Eva Lou Apel & Barbara
Schumann.
Chemical Education Consultant Barbara J. Schumann 1405 Thaddeus Cove
Austin, Texas 78746-6321 512-327-5449
Fax: 512-327-6207 E-mail: [email protected]
Chemical Education Consultant
Eva Lou Apel 2506 Plantation Creek Court Missouri City, TX 77459-291
281-499-2708 E-mail: [email protected]
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The Dynamic Duo
Foreword
Eva Lou and Barbara taught together at Westlake High School in Austin from 1982 – 1993. They team taught chemistry. They developed many labs and teaching ideas. They gave many workshops together. They continue to give workshops together. In their early years of teaching together Eva Lou and Barbara started a demo club. They had a student named Robbie. He was a member of the demo club. Barbara taught him one semester and Eva Lou the other. He named them the “Dynamic Duo”. He gave them Tee shirts for Christmas with the “Dynamic Duo” lettering on them. The name stuck. They still have those shirts. Eva Lou Apel BS Chemistry-Texas Woman’s University. Graduate work --- Texas A&M University, Hope College, University of California at Berkeley and the University of Arizona. Eva Lou has taught physical science, chemistry and AP chemistry for 26 years in the Waco, Texas Public Schools, Houston, Texas Public Schools, and at Westlake High in Austin, Texas before retiring in 1993. She also has worked in the analytical chemistry lab for Shell Development Company’s Research Lab in Houston. For the past seven years she has worked as an Independent Representative for George Seidel and Associates rep-resenting Flinn Scientific. Eva Lou has attended many NSF summer institutes including the AP Chemistry Workshop at Hope College, the Woodrow Wilson Chemistry Institute at Princeton in 1986, the ICE Institute at Berkeley, and the ICE Institute at the University of Arizona. She received the Texas Excellence Award for Outstanding High School Teachers from the University of Texas in 1987, the Outstanding Chemistry Teacher Award from the Central Texas Section of the ACS in 1988 and was named as a Life Time Honorary Member of the Texas Chem-istry Teachers organization in 1994. She has presented over seventy-five workshops at the local, state and national levels. Barbara J. Schumann BS chemistry – University of Texas at Austin. Graduate Work – University of New York at New Paltz, University of California at Berkeley, and the University of Michigan at Ann Ar-bor. Barbara taught algebra, physical science and chemistry for 20 years in the Houston, Austin and Eanes Public School Systems and in Wappingers Falls Central School District in New York. She substituted for 12 years in New York. She attended many NSF summer institutes including the Woodrow Wilson Institute at Princeton in 1989, the ICE Institute at Berkeley, the ICE Institute at the University of Michi-gan at Ann Arbor, Frontiers in Science at Tufts University, and was trained in Teaching Science with Toys at the University of Ohio at Miami of Ohio. She was trained by the American Chemical Society in Operation Chemistry at the University of Wisconsin and Purdue University. She was a member of the Central Texas Operation Chemistry team for several years.
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The Dynamic Duo
Foreword She was selected by the Central Texas Region of the American Chemical Society as the Chemistry Teacher of the year in Travis County in 1989, nominated for the Presidential Award in Teaching in 1989, selected at the Chemistry Teacher of the year in the state of Texas by the Associated Chemistry Teachers of the State of Texas in 1997 and received the Spirit of Education Award at Westlake High School in 1998. She was awarded an honorary membership in the Associated Chemistry Teachers of the State of Texas. She has served for several years as the historian of that organization. Since 1998 she has worked as an independent representative for George Seidel and As-sociates representing Flinn Scientific. She has presented over 100 workshops.
Eva Lou Barbara
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The Dynamic Duo
Contents
A. Order of Teaching First Semester Objectives A-2 Second Semester Objectives A-4 Calendar A-7
B. Basic Information Element List B-2 Relative Atomic Mass of Chemical Elements B-3 Formula Weight Reference B-6 Oxidation Numbers B-7 Periodic Table B-9
C. Teaching Aids Acids & Bases (pH) C-2 Covalent Nomenclature C-3 Conversions C-4 Solving Density Problems C-5 Significant Digits C-6 Redox Equations C-7 Combined Gas Laws C-8 Acid Formulas C-9 Balancing Equations C-10 Oxidation Numbers for Polyatomics C-12 Flow Chart for Formula Writing C-13 Flow Chart for Naming Compounds C-14 Chem Country Hall C-15 Sodium Chloride Dialog C-16 Atomic Theory Poems C-18
D. Mini Labs Just How Many in a Mole? D-2 Molarity D-3 Massing Moles D-4 Rainbow Tube D-6 Types of Reactions D-8 Boiling Water in a Syringe D-9 Experiencing a Chemical Reaction D-10 Boiling Water in a Paper Cup D-11
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Contents
Voice Activated Chemical Reaction D-12 Soda Can Crunch D-13 Marshmallow in a Syringe D-14
E. Labs Electroplating Copper E-2 Testing Antacid Tablets E-3 Vitamin C Content of Fruit Juices E-6 Boyles Law E-12 Acid Decomposition E-13 Electrolysis E-18 Micro Mixture Separation E-19 Making Strawberry Soda E-21 CO2 (g)/CO2 (aq) Equilibrium E-23 Molar Mass of Butane E-25 Composition of Hydrates E-27 Journey into the Atom E-32 Mole & Mass Relationships E-33 Relative Strengths of Acids & Bases E-35 How Do you Know a Chemical Reaction is Happening? E-39 Qualitative Polymer Lab E-44 Acid Rain Project E-50 Half Life Simulation E-52 Colligative Properties E-55 Micro Titration Apparatus E-58 Top Secret—For Your Eyes Only E-59
F. Lab Management Check List F-2 Chemistry Pledge & Songs F-3 Safety Test Lab Practical F-4 Putting Polyvinyl Alcohol into Solution F-5 Relative Strength of Acids & Bases Inventory F-6 Money Saving Tips F-7
G. Teaching Demos Determination of the Molar Volume of Carbon Dioxide G-2 Strong Acid & Strong Base G-6
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Contents
Weak Acid & Strong Base G-7 Weak Base & Strong Acid G-8 Rainbow Cylinder G-9 Determination of the Molecular Weight of CO2 G-12 Can Shaker G-15 Shaving in a Vacuum G-16 Hints for Demos & Demo Shows G-17
H. Ways to Teach Topics Rules for Writing Equations H-2 Dimensional Analysis Problems H-4 Periodic Table with Electron Configurations H-7
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First Semester Chemistry 1 Objectives
Unit 1: Lab Safety and Equipment Given equipment or supplies, the student will be able to identify or demonstrate the correct safe use of the equipment or supply. (1a) Unit 2: Classification of Matter • The student will be able to identify matter and energy and heterogeneous and homo-
geneous substances. (7b, 8a) • The student will be able to identify examples of physical and chemical properties. (6a,
6b, 7b, 10b) • The student will be able to classify changes which occur in matter as physical, chemi-
cal or nuclear changes. (2a, 2b, 4a, 5a, 6b, 7a,8a,19a) • The student will be able to classify matter as element, compound or mixture. (2a, 7b,
8a) Unit 3: Formula Writing The student will be able to write chemical formulas for elements, ionic compounds and covalent compounds. (4a, 4b) Unit 4: Nomenclature The student will be able to name compounds given the formula. (4b) Unit 5: Equations • The student will be able to verify the law of conservation of matter by balancing equa-
tions. (4a, 4b, 6b} • Given the reactants and products, the student will be able to write an equation to rep-
resent chemical change. (3a, 4a, 4b,5a, 9b) • Given the reactants, the student will be able to classify as to type of reaction, predict
products, and write a balanced equation for the four basic types of chemical reactions. (2a, 3a, 4a, 4b, 5a, 7b, 9b)
Unit 6: Measurements and Calculations • The student will be able to perform accurate measurements in the metric system using
the units of length, temperature, mass and volume to the correct number of significant figures. (5a)
• The student will be able to solve problems involving the addition, subtraction, multipli-cation, and division of numbers written in scientific notation; measurements made to the correct number of significant figures; density, mass and volume; and percent rela-tive error in data. (5a, 9a)
• The student will be able to use the factor-label method to make conversions between any units of measure, given the quantitative relationship between the units. (4b)
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First Semester Chemistry 1 Objectives
• Given data, the student will be able to plot the data on a graph. (5b) Unit 7: The Mole Concept • The student will demonstrate knowledge of Avogadro’s number by inter-converting the
number of moles, molecules and atoms present in a given mass of an element or com-pound. (3a, 9b, 7a, 4b)
• The student will be able to calculate the molecular or formula weight for a given com-pound from a table of atomic weights, calculate the percent composition for a given compound, determine the empirical formula for a compound given either the weight of each element in the compound or the percentage composition of the compound and derive the molecular formula for a compound when given its empirical formula and its molecular mass. (7r, 1 r, 2r, 4b, 5a)
Unit 8: Stoichiometry • The student will solve stoichiometric problems (mass-mass, mass-volume, volume-
volume). (2a, 5a, 3a, 9b, 7a) • The student will be able to predict whether a chemical reaction is endothermic or exo-
thermic based on enthalpy calculations. (3a, 9b, 4b, 5a, 7a, 6a, 6b) Unit 9: Atomic Theory • The student will be able to compare properties of protons, neutrons and electrons. (4b,
7c, 7b) • The student will be able to describe two isotopes of an element in terms of the number
of protons, electrons and neutrons. (4b, 7b, 7c) • The student will be able to diagram an atom giving the spdf electron configuration
when given the atomic number and atomic mass of the element. (4b, 7b, 7c) • The student will be able to draw an electron dot diagram for an atom with atomic num-
ber given. (4b, 7b, 7c) • The student will be able to use the periodic table to classify elements as metals, metal-
loids, nonmetals or noble gases; predict oxidation numbers of common elements; pre-dict chemical and physical properties of elements; predict principal quantum numbers for electrons in a specific atom; list specific similarities and differences of properties within families of elements in groups IA to VIIA with emphasis on trends in properties; and trace periodic trends in ionization energy, electron affinity, electronegativity, and bond character of elements in the periodic table. (4b, 3a, 7b, 7c)
Unit 18: Chemical Bonding • The student will be able to describe ionic, covalent and metallic bonds and to compare
properties associated with each of the bond types. (7c, 7b) • The student will be able to predict whether a specific bond will be predominantly polar
covalent, nonpolar covalent or ionic using a table of electronegativities. (7a, 7b, 7c, 6b) • The student will be able to draw dot diagrams for simple compounds, predict shape,
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Second Semester Chemistry 1 Objectives
Unit 11: Kinetic Theory of Matter • The student will be able to list the three basic assumptions of the kinetic theory. (4B) • The student will be able to define the general characteristics of the three states of mat-
ter and distinguish plasma as a special state. (3B, 7A, 8A)) • The student will be able to compare and contrast crystalline and amorphous solids.
(8A) Unit 12: Gas Laws • The student will be able to change gas pressure measured in mm of Hg to atmos-
pheres and vice versa, use Boyle's Law to solve volume-pressure problems, use Charles' Law to solve volume-temperature problems, use the combined gas law, in-cluding correction for water vapor pressure to solve volume-pressure-temperature problems and calculate volume, pressure, molecular weight or number of moles of gas using the Ideal Gas Law. (4A, 4B, 5B, 6A, 6B, 9A, 9B)
Unit 13: Solutions • The student will be able to list factors which affect solution rate. (4A, 6A, 9A, 9A) • The student will be able to calculate the percent solute, molarity, and molality of a so-
lution given the mass of solute dissolved in a known quantity of water. (4A, 6A) • The student will be able to list and describe the factors affecting solubility. (4A, 6A, 9A) • The student will be able to use the colligative properties of a substance to determine
its boiling point, and freezing point in a water solution. (6A, 10A, 9A, 9B) Unit 14: Qualitative Analysis & Net Ionic Equations • The student will be able to explain the ionization process and write equations which
represent these reactions. (4A, 4B) • The student will be able to write net ionic equations for a reaction. (4A, 4B) • Given a solution the student will be able to outline the procedure to identify the ions by
using the qualitative analysis flow chart. (3B) Unit 15: Kinetics and Equilibrium • The student will be able to explain factors which influence reaction rate. (1A, 2A, 2B,
5A, 5B) • The student will be able to describe a catalyst and the concept of activation energy.
(8A, 10 A) • The student will be able to write the equilibrium expression for a given reversible reac-
tion, calculate the value of Keq and explain the significance of the numerical value of Keq. (4A, 4B, 5A, 5B)
• The student will be able to predict the effect of applying stress to a system at equilib-rium according to LeChatelier's Principle. (6A, 6B, 9A, 9B)
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Second Semester Chemistry 1 Objectives
Unit 16: Acids, Bases and Salts • The student will be able to describe and identify acids and bases according to the Ar-
rhenius, Bronsted-Lowery, and Lewis acid-base theories. (3A) • The student will be able to list the properties (chemical and physical) of acids and
bases according to the Arrhenius definition. (8A) • The student will be able to differentiate between strong acids and weak acids and be-
tween strong bases and weak bases. (8A) • The student will be able to describe the pH scale, give the approximate location on the
scale of some common substances, solve for the pH of a solution of known (H+) em-ploy Kw to solve for (OH-) when {H+) is known in an aqueous solution, explain hy-drolysis and describe a buffer solution and its use. (4A, 4B 8A)
• The student will be able to use titration procedures in volumetric analysis and use the data obtained to calculate either volume or concentration of one factor. (2A, 6B. 9A. 9B)
• The student will be able to use indicators to determine the pH of an unknown solution. (2A, 5A. 8A)
Unit 17: Oxidation-Reduction Reactions • The student will be able to assign oxidation numbers to elements in a compound and
identify the substance being oxidized, the substance being reduced, the oxidizing agent, and the reducing agent in the reaction. (4A, 4B, 7A, 7B, 8A)
• The student will be able to balance the equation for a given oxidation-reduction reac-tion by the electron transfer method or the half reaction method. (4A, 4B)
• The student will be able to compare and contrast an electrochemical and electrolytic reaction, write equations for the half-cell reactions at the anode and cathode and give practical examples of electrochemical tells. (7A, 7B, 10A)
Unit 18: Organic Chemistry • The student will be able to recognize; name, give empirical formulas and draw struc-
tural formulas for these types of hydrocarbons: alkanes, alkenes, alkynes and aromat-ics. (3A, 4A, 4B, 7B)
• The student will be able to identify the functional group associated with alcohols, ac-ids, esters, aldehydes, and ketones. (3A. 4A, 4B. 7B)
• The student will be able to recognize, name and draw structural formulas for these types of hydrocarbon derivatives: alkyl halides, alcohols, ethers, aldehydes, ketones, acids, esters, amines, amino acids. (3A, 4A, 4B, 7B)
• The student will be able to classify and describe chemically the nature and structure of polymers, fats, carbohydrates and proteins and distinguish between soaps and deter-gents. (3A. 4A, 4B, 1B, 10A)
Unit 19: Nuclear Reactions • The student will be able to list the three basic types of fundamental radiations, give the
characteristics of each, write and balance nuclear equations involving atoms losing
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Second Semester Chemistry 1 Objectives
alpha particles or beta particles and for atoms being bombarded by alpha particles, neutrons and protons. (2B, 4A, 7A, 10A)
• The student will be able to compare fission and fusion and their uses in the everyday world. (9A, 9B. 10A)
• The student will be able to explain the concept of half life. (2B. l0A) • The student will evaluate career implications of chemistry and of nuclear principles by
reporting on science current events (10B)
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Calendar
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Mon Key: The following let-ters are used to organize informa-tion on the calen-dar.
Tue Wed Thu Fri
A School remind-ers C Quizzes E Overview of topic G Demos I Labs K tests L, M Practice O Class reminders
1 2
5
6 7 8 9
12 A Classes Begin YEA! E Hand outs & Safety G Demos O Signature form due Wed.
13 E Assign Groups & Gp. Exer. E Safety Rules & Equipment E Video Safety (?) L PR 1-1 HOut Safety Questions
14 E Pre-lab I Do Lab 1-1 Tech-niques O Test Unit 1 Fri-day 8/16
15 I Finish Lab 1-1& Post Lab L Learn Symbols by 8/20 O Test tomorrow incl. practical
16 C Quiz Math Skills (after test) K Test Unit 1 L PR 2-1 Read pp24-6, 38-50, 80-82
19 E Physical & Chemical Change E Video Elements, Cmpds. & Mixtures G Demo Sugar & H2S04; Candle L PR 2-2 Phys & Chern Prop HOut
20 C QZ 2-1 Symbols I Lab 2-1 Know Chern. Change L PR 2-3 HOut + Classify + p49 #1-9
21 I Lab 2-2 Iron- Sulfur O Test Unit 2 Fri-day E Unit 2 Re-view 8/23
22 C QZ 2-2 Symbols I Minilab 2-1 Chro-matography O Test tomorrow Unit 2
23 K Test Unit 2 L Learn Polya-tomic Ions by 8/27 L PR 3-1 Rd & notes pp50-70
26 E Assign Perm. Groups; Activity E Ions & Ionic For-mulas L PR 3-2 HOut Formula Chart
27 A Open House C QZ 3-1 Formula Chart E Ionic Formulas from Names L PR 3-3 HOut Ionic Formula from Name
28 A Faculty Meeting C QZ 3-2 Ionic Formula E Acid Formulas G Demo Acid Rain L PR 3-4 Hout Acid-Salt
29 E Binary Covalent & Elem. Formulas L PR 3-5 HOut Covalent
30 C QZ 3-3 Acid & Polyatomic Ions E Mixed Formulas G Demo Zinc & Iodine L PR 3-6 HOut O Progress reports
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Element List
Metals Metalloids Nonmetals hydrogen H boron B carbon C lithium Li silicon Si nitrogen N sodium Ne arsenic As phosphorus P potassium K antimony Sb oxygen 0 rubidium Rb sulfur S cesium Cs selenium Se beryllium Be fluorine F magnesium Mg chlorine Cl calcium Ca bromine Br strontium Sr iodine I barium Ba helium He chromium Cr manganese Mn iron Fe cobalt Co nickel Ni copper Cu zinc Zn silver Ag cadmium Cd platinum Pt gold Au mercury Hg boron B aluminum Al tin Sn lead Pb bismuth Bi uranium U
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Relative Atomic Masses of the Chemical Elements
Name Symbol Atomic Number Atomic Mass Actinium Ac 89 227.0278 Aluminum(a) Al 13 26.98154 Americium Am 95 (243) Antimony Sb 51 121.75* Argon(b,c) Ar 18 39.948* Arsenic As 33 74.9216 Astatine At 85 (210) Barium(c) Ba 56 137.33 Berkelium Bk 97 (247) Beryllium Be 4 9.01218 Bismuth Bi 83 208.9804 Boron(b,d) B 5 10.81 Bromine Br 35 79.904 Cadmium(c) Cd 48 112.41 Cesium Cs 55 132.9054 Calcium(c) Ca 20 40.08 Californium Cf 98 (251) Carbon(b) C 6 12.011 Cerium(c) Ce 58 140.12 Chlorine Cl 17 35.453 Chromium Cr 24 51.996 Cobalt Co 27 58.9332 Copper(b) Cu 29 63.546* Curium Cm 96 (247) Dysprosium Dy 66 162.50* Einsteinium Es 99 (254) Erbium Er 68 167.26* Europium(c) Eu 63 151.96 Fermium Fm 100 (257) Fluorine F 9 18.998403 Francium Fr 87 (223) Gadolinium(c) Gd 64 157.25* Gallium Ga 31 69.72 Germanium Ge 32 72.59* Gold Au 79 196.9665 Hafnium Hf 72 178.49* Helium(c) He 2 4.00260 Holmium Ho 67 164.9304 Hydrogen(b) H 1 1.0079 Indium(b) In 49 114.82 Iodine I 53 126.9045 Iridium Ir 77 192.22* Iron Fe 26 55.847* Krypton(c,d) Kr 36 83.80 Lanthanum(c) La 57 138.9055* Lawrencium Lr 103 (260) Lead(b,c) Pb 82 207.2 Lithium(b,c,d) Li 3 6.941* Lutetium Lu 71 174.97 Magnesium(c) Mg 12 24.305
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Relative Atomic Masses of the Chemical Elements
Name Symbol Atomic Number Atomic Mass Manganese Mn 25 54.9380 Mendelevium Md 101 (258) Mercury Hg 80 200.59* Molybdenum Mo 42 95.94 Neodymium(c) Nd 60 144.24* Neon(d) Ne 10 20.179* Neptunium(a) Np 93 237.0482 Nickel Ni 28 58.70 Niobium Nb 41 92.9064 Nitrogen N 7 14.0067 Nobelium No 102 (259) Osmium(c) Os 76 190.2 Oxygen(b) O 8 15.9994* Palladium(b) Pd 46 106.4 Phosphorus P 15 30.97376 Platinum Pt 78 195.09* Plutonium Pu 94 (244) Polonium Po 84 (209) Potassium K 19 39.0983* Praseodymium Pr 59 140.9077 Promethium Pm 61 (145) Protactinium(a) Pa 91 231.0359 Radium(a,c) Ra 88 226.0254 Radon Rn 86 (222) Rhenium Re 75 186.207 Rhodium Rh 45 102.9055 Rubidium(c) Rb 37 85.4678* Ruthenium(c) Ru 44 101.07* Samarium(c) Sm 62 150.4 Scandium Sc 21 44.9559 Selenium Se 34 78.96* Silicon Si 14 28.0855* Silver(c) Ag 47 107.868 Sodium Na 11 22.98977 Strontium(c) Sr 38 87.62 Sulfur(b) S 16 32.06 Tantalum Ta 73 180.9479* Technetium Tc 43 (97) Tellurium(c,d) Te 52 127.60* Terbium Tb 65 158.9254 Thallium Tl 81 204.37* Thorium(a,c) Th 90 232.0381 Thulium Tm 69 168.9342 Tin Sn 50 118.69* Titanium Ti 22 47.90* Tungsten W 74 183.85* Uranium(c,d) U 92 238.029 Vanadium V 23 50.9414* Xenon(c,d) Xe 54 131.30 Ytterbium Yb 70 173.04*
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Relative Atomic Masses of the Chemical Elements
From Chemical Sciences Data Tables, http;//www.ualberta.ca/~jplambec/che/data/p00402 Notes: The relative atomic masses of many elements are not invariant, but depend on the origin and treatment of the material. The footnotes elaborate the types of variation to be ex-pected for individual elements. The values given here apply to elements as they exist naturally on earth and to certain artificial elements. When used with due regard to the foot-notes they are considered reliable to +/- 1 in the last digit (or +/- 3 when followed by an asterisk). Values in parentheses are used for certain radioactive elements whose relative atomic masses cannot be quoted precisely without knowledge of origin; the value given is the atomic mass number of the isotope of that element of longest known half-life. These values are scaled to the relative atomic mass of 12C as exactly twelve. (a) Element for which the value given is that of the radioisotope of longest half-life. (b) Elements for which known variations in isotopic composition in normal terrestrial mate-rial prevent a more precise relative atomic mass being given; values should be applicable to any "normal" material. (c) Element for which geological specimens are known in which the element has an anomalous isotopic composition, such that the difference in relative atomic mass of the element in such specimens from that given in the table may exceed considerably the im-plied uncertainty. (d) Element for which substantial variations from the value given can occur in commer-cially available material because of inadvertent or undisclosed change of isotopic compo-sition.
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Formula Weight Reference
Name Formula Weight
Name Formula Weight
Acetic Acid 60.05 Nitric Acid 63.01 Acetone 58.08 Oxalic Acid 90.04 Aluminum Hydroxide 78.00 Phosphoric Acid 98.00 Ammonium Acetate 77.08 Potassium Bitartrate 188.2 Ammonium Chloride 53.49 Potassium Bromide 119.0 Ammonium Dichromate 252.1 Potassium Carbonate 138.2 Ammonium Hydroxide 35.05 Potassium Chlorate 122.6 Ammonium Nitrate 80.04 Potassium Chloride 74.56 Ammonium Sulfate 132.2 Potassium Chromate 194.2 Barium Carbonate 197.4 Potassium Dichromate 294.2 Barium Chloride 208.2 Potassium Hydroxide 56.11 Barium Hydroxide 171.4 Potassium Iodate 214.0 Barium Nitrate 261.4 Potassium Iodide 166.0 Barium Sulfate 233.4 Potassium Nitrate 101.1 Benzene 78.11 Potassium Permanganate 158.0 Calcium Carbonate 100.1 Potassium Phosphate 212.3 Calcium Chloride 111.0 Potassium Sulfate 174.3 Calcium Hydroxide 74.10 Propyl Alcohol 60.10 Calcium Nitrate 164.1 Silver Nitrate 169.9 Calcium Phosphate 310.18 Sodium Acetate 82.03 Cobalt (Ii) Chloride 129.9 Sodium Bicarbonate 84.01 Cupric Chloride 134.5 Sodium Bromide 102.9 Cupric Sulfate 159.6 Sodium Carbonate 106.0 Ethyl Alcohol 46.07 Sodium Chlorate 106.5 Ferric Chloride 162.2 Sodium Chloride 58.45 Ferric Sulfate 399.9 Sodium Chromate 161.0 Glucose 180.0 Sodium Hydroxide 40.00 Hydrochloric Acid 36.46 Sodium Nitrate 84.99 Hydrofluoric Acid 20.01 Sodium Phosphate 163.9 Hydrogen Peroxide 34.02 Sodium Sulfate 142.0 Lead Acetate 325.3 Sodium Sulfite 126.1 Lead Chloride 278.1 Sodium Tartrate 194.1 Lead Nitrate 331.2 Sodium Thiosulfate 158.1 Lithium Carbonate 73.89 Strontium Nitrate 211.6 Lithium Chloride 42.40 Sucrose 342.3 Lithium Hydroxide 23.94 Sulfuric Acid 98.08 Magnesium Chloride 95.23 Water 18.02 Magnesium Hydroxide 58.34 Zinc Chloride 136.3 Magnesium Sulfate 120.4 Zinc Nitrate 189.4 Manganous Sulfate 151.0 Zinc Sulfate 161.4 Nickel (Ii) Nitrate 182.7
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Oxidation Number
Positive Ions Negative Ions Name Symbol Charge Name Symbol ChargeAluminum Al+3 +3 *Acetate C2H3O2
-1 -1 *ammonium NH4
+1 +1 *bromate BrO3-1 -1
Antimony (III) Sb+3 +3 bromide Br-1 -1 Antimony (V) Sb+5 +5 *carbonate CO3
-2 -2 arsenic(III) As+3 +3 carbide C-4 -4 Arsenic (V) As+5 +5 *chlorate ClO3
-1 -1 barium Ba+2 +2 chloride Cl-1 -1 Bismuth (III) Bi+3 +3 *chlorite ClO2
-1 -1 Bismuth (V) Bi+5 +5 *chromate CrO4
-2 -2 cadmium Cd+2 +2 *cyanide CN-1 -1 calcium Ca+2 +2 *dichromate Cr2O7
-2 -2 cesium Cs+1 +1 *dihydrogen phosphate H2PO4
-1 -1 chromium(II) Cr+2 +2 fluoride F-1 -1 chromium (III) Cr+3 +3 hydride H-1 -1 cobalt (II) Co+2 .+2 *hydrogen carbonate HCO3
-1 -1 coba1t ( III) Co+3 +3 *hydrogen sulfate HSO4
-1 -1 copper (I), cuprous Cu+1 +1 *hydrogen phosphate HPO4
-2 -2 copper (II), cupric Cu+2 +2 *hydroxide OH-1 -1 hydrogen H+1 +1 *hypochlorite ClO-1 -1 iron (II) Fe+2 +2 *iodate IO3
-1 -1 iron (III), ferric Fe+3 +3 iodide I-1 -1 lead (II), plumbous Pb+2 +2 *nitrate NO3
-1 -1 Lead (IV), plumbic Pb+4 +4 nitride N-3 -3 lithium Li+1 +1 *nitrite NO2
-1 -1 magnesium Mg+2 +2 *oxalate C2O4
-2 -2 manganese (II) Mn+2 +2 oxide O-2 -2 manganese (IV) Mn+4 +4 *perchlorate ClO4
-1 -1 Mercury (I), mercurous Hg+2 +2 *periodate IO4
-1 -1 mercury(II), mercuric Hg+2 +2 *permanganate MnO4
-1 -1 nicke1 (II) Ni+2 +2 *peroxide O2
-2 -2 nickel (III) Ni+3 +3 *phosphate PO4
-3 -3 potassium K+1 +1 phosphide P-3 -3 rubidium Rb+1 +1 *phosphite PO3
-3 -3 silver Ag+1 +1 *silicate SiO4
-4 -4 sodium Na+1 +1 *sulfate SO4
-2 -2 strontium Sr+2 +2 sulfide S-2 -2 tin (II), stannous Sn+2 +2 *sulfite SO3
-2 -2 tin (IV), stannic Sn+4 +4 *thiocyanate SCN-1 -1 zinc Zn+2 +2 *thiosulfate S2O3
-2 -2
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Oxidation Number
Name Formula Weight
Name Formula Weight
Acetic Acid 60.05 Nitric Acid 63.01 Acetone 58.08 Oxalic Acid 90.04 Aluminum Hydroxide 78.00 Phosphoric Acid 98.00 Ammonium Acetate 77.08 Potassium Bitartrate 188.2 Ammonium Chloride 53.49 Potassium Bromide 119.0 Ammonium Dichromate 252.1 Potassium Carbonate 138.2 Ammonium Hydroxide 35.05 Potassium Chlorate 122.6 Ammonium Nitrate 80.04 Potassium Chloride 74.56 Ammonium Sulfate 132.2 Potassium Chromate 194.2 Barium Carbonate 197.4 Potassium Dichromate 294.2 Barium Chloride 208.2 Potassium Hydroxide 56.11 Barium Hydroxide 171.4 Potassium Iodate 214.0 Barium Nitrate 261.4 Potassium Iodide 166.0 Barium Sulfate 233.4 Potassium Nitrate 101.1 Benzene 78.11 Potassium Permanganate 158.0 Calcium Carbonate 100.1 Potassium Phosphate 212.3 Calcium Chloride 111.0 Potassium Sulfate 174.3 Calcium Hydroxide 74.10 Propyl Alcohol 60.10 Calcium Nitrate 164.1 Silver Nitrate 169.9 Calcium Phosphate 310.18 Sodium Acetate 82.03 Cobalt (Ii) Chloride 129.9 Sodium Bicarbonate 84.01 Cupric Chloride 134.5 Sodium Bromide 102.9 Cupric Sulfate 159.6 Sodium Carbonate 106.0 Ethyl Alcohol 46.07 Sodium Chlorate 106.5 Ferric Chloride 162.2 Sodium Chloride 58.45 Ferric Sulfate 399.9 Sodium Chromate 161.0 Glucose 180.0 Sodium Hydroxide 40.00 Hydrochloric Acid 36.46 Sodium Nitrate 84.99 Hydrofluoric Acid 20.01 Sodium Phosphate 163.9 Hydrogen Peroxide 34.02 Sodium Sulfate 142.0 Lead Acetate 325.3 Sodium Sulfite 126.1 Lead Chloride 278.1 Sodium Tartrate 194.1 Lead Nitrate 331.2 Sodium Thiosulfate 158.1 Lithium Carbonate 73.89 Strontium Nitrate 211.6 Lithium Chloride 42.40 Sucrose 342.3 Lithium Hydroxide 23.94 Sulfuric Acid 98.08 Magnesium Chloride 95.23 Water 18.02 Magnesium Hydroxide 58.34 Zinc Chloride 136.3 Magnesium Sulfate 120.4 Zinc Nitrate 189.4 Manganous Sulfate 151.0 Zinc Sulfate 161.4 Nickel (Ii) Nitrate 182.7
Activity Series Metals potassium sodium lithium barium strontium calcium magnesium Aluminum zinc chromium iron cadmium cobalt nickel tin 1ead hydrogen copper mercury silver platinum gold Nonmetals fluorine chlorine bromine iodine sulfur
B - 9
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Periodic Table
From: http://www.dayah.com/periodic/ Note: This is a dynamic periodic table on the web. Each ele-ment links to its properties.
C—1
Apel & Schumann
C—2
Acids & Bases
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100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10- 2 10-1 100
H+
OH-
ACID
BASE
H+
OH-
100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10- 2 10-1 100
H+
OH-
ACID
BASE
H+
OH-
100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10- 2 10-1 100
H+
OH-
ACID
BASE
H+
OH-
100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10- 2 10-1 100
H+
OH-
ACID
BASE
H+
OH-
100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10- 2 10-1 100
H+
OH-
ACID
BASE
H+
OH-
100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10- 2 10-1 100
H+
OH-
ACID
BASE
H+
OH-
100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10- 2 10-1 100
H+
OH-
ACID
BASE
H+
OH-
100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10- 2 10-1 100
H+
OH-
ACID
BASE
H+
OH-
100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10- 2 10-1 100
H+
OH-
ACID
BASE
H+
OH-
C—3
Covalent Nomenclature
1. Diatomic Elements: I Bring Clay For Our New House 2. Prefixes: Mono, Di, Tri, Tetra, Penta, Hexa 3. Oxygen: Dinitrogen Monoxide Nitrogen Oxide Dinitrogen Trioxide Nitrogen Dioxide Dinitrogen Tetroxide Dinitrogen Pentoxide 4. Write the formula of the following substances:
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The last vowel of the pre-fix is dropped before the "O" in oxygen
Compound Formula 1. Germanium Tetrafluoride
2. Silicon Dioxide
3. Carbon Dioxide
4. Diphosphorous Pentoxide
5. Sulfur Dioxide
6. Iodine
7. Carbon Monoxide
8. Nitrogen Trichloride
9. Carbon Tetrachloride
10. Arsenic Pentoxide
11. Sulfur Trioxide
12. Selenium Dioxide
13. Phosphorous Pentoxide
14. Oxygen
15. Selenium Tetrafluoride
16. Silver
17. Carbon Disulfide
18. Phosphorous Tribromide
19. Diantimony Pentasulfide
20. Hydrogen
Bergin Grimes Enterprises, 504 Congress .Avenue, Austin, Texas 78701
C—4
Conversions
Mass-Mass Mass to Moles Multiply By Mole Ratio Change Moles Back to Grams That's Mass-Mass, If You Say So Mass-Volume Grams to Liter Mass to Moles Multiply By Mole Ratio Change Moles to Liters That's Mass-Volume, If You Say So. Liters to Grams Liters to Moles Multiply By Mole Ratio Change Moles to Grams That's Mass-Volume, If You Say So. Volume-Volume Change Mole Ratio to Liters Multiply By Known Liters
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C—5
Solving Density Problems
The Dynamic Duo
M
D V
Put finger over what you are solving for. The formula you need will magi-cally appear.
Density is always the same for a pure substance. D=M/V V=M/D M=VD • Write down given and formula • Substitute • Solve Examples: • Mass=6.0 grams, Volume=3.0 cm3 , Density=?
• D=M/V • D=6.0 g/3.0 cm3 • D=2.0 g/cm3
• Density=2.0 g/ml, Mass=20.0 g, Volume=?
• V=M/D • V=20.0 g/(2.0 g/ml)=20.0 g x ml/2.0 g=10 ml
• Density=6.0 g/ml, Volume=5.0 ml, Mass=?
• M=DV • M=(6.0g/ml)x(5.0 ml) • M=30.0 g
C—6
Significant Digits
The accuracy of the final answer to a problem depends upon the accuracy of the numbers used to express each measurement used. The accuracy of any measurement depends upon the instrument which is used and upon the observer. The digits in an answer which imply more accuracy than the measurements justify are not significant and should be dropped so that those digits which remain truly imply the accuracy of the original measure-ments. The remaining digits are called significant digits. Significant digits consist of the definitely known digits plus one estimated digit. The mass of a chemical is 15.76 grams. This meas-urement has four significant digits. The last digit, 6, has probably been estimated but the mass of the chemi-cal is definitely between 15.7 g and 15.8 g. Exact numbers have an infi-nite number of significant digits. Exact numbers are "counts," not measurements. Thus, you may have 24 students, exactly, in a class. You cannot have' 24.1 students. Relationships, such as 1 minute = 60 seconds contain exact numbers. Exact numbers can have any number of zeros to the right of the decimal point or last non-zero digit. Exact numbers, such as the 2 in 2(3.1416), do not limit the number of significant digits in a calculation. The following rules are used to determine the number of significant digits: 1. Digits other than zero are always significant. 2. Any final zero or zeros used after the decimal point are significant. 3. Zeros between two other significant digits are always significant. Zeros used solely for spacing the decimal point are not significant. The following examples illustrate these rules:
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Example Number of Significant Digits
Example Number of Significant Digits
35 Two 0.246 Three 3.57 Three 0.004 One 3.507 Four 24.068 five 0.035 Two 268 Three 5.700 Four 20.4680 Six 53.0 Three 2400 Two
Pacific Ocean(Present Decimal) Atlantic Ocean
(Absent Decimal)
70803009000
.003053.40203.502
Pacific Ocean(Present Decimal) Atlantic Ocean
(Absent Decimal)
70803009000
.003053.40203.502
C—7
Redox Applications
Leo Ger
(Leo The Lion Goes Ger) 1. All Reactions
Oxidation - Annode - Two Vowels: An Ox. Reduction - Cathode- Two Consonants: Red Cat
2. Electrolytic (E.PA – Decomposition) Electric Current Forces A Reaction Negative Electrode- Cathode Positive Electrode- Annode Positive Ions Migrate Toward Negative And Negative Towards Positive
3. Electrochemical (Voltaic - V N A) Chemical Process Produces Flow Of Electrons Negative Electrode - Annode Positive Electrode - Cathode
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C—8
Combined Gas Laws P1V1/T1 = P2V2/T2 P1V1T2 = P2V2T1 Remember: = Vice President / Treasurer EXAMPLE: If the gas occupies a volume of 100. ml at a pressure of 760. mm of mercury and 27.0 degrees C, what volume will the gas occupy at 800. mm of mercury and 50.0 degrees C?
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C—9
Acid Formulas
Rules:
Practice:
The Dynamic Duo
Salt Acid
Negative Ion
ide Hydro___ic
ate ic
itc ous
Per___ate Per___ic
Hypo___ite Hypo___ous
Acid Salt
Sulfuric
Hydrochloric
Nitrous
Perchloric
Hypoclorite
C—10
Balancing Equations
1. Balance the equation. There must be the same number of atoms of each element on both sides of the equation; they are just arranged differently in molecules. The num-bers of atoms are balanced by putting numbers, called coefficients, in front of the molecules. You may never put coefficients in the middle of a formula. Do not change the subscripts!
2. Equations are easier to balance if the oxygen atoms are left to the last to be balanced and the hydrogen atoms next to last.
3. Whenever possible, balance by groups rather than by individual-elements. The groups must be on both sides of the equation.
4. Water can be written either H2O or HOH. When water is on one side and an oxide is on the other, write water H2O. When water is on one side and a hydroxide is on the other, write water HOH.
5. If you find yourself going from one side of the equation to the other using increasingly, larger numbers, you probably have a formula wrong. Erase all the coefficients in front of the molecules and check each formula carefully.
The Dynamic Duo
CH4 + O2 → CO2 + H2O
Calcium nitrate + phosphoric acid gives calcium phosphate + nitric acid Ca(N03)2 + H3(PO4) → Ca3(P04)2 + H(N03) Get the nitrate and phosphate groups equal on each side. Balance this equation.
Aluminum hydroxide + nitric acid gives aluminum nitrate + water Al(OH)3 + HNO3 → Al(NO3)3 + HOH Aluminum oxide + nitric acid gives aluminum nitrate + water Al2O3 + HNO3 → Al(NO3)3 + H2O Balance these equations.
C—11
Balancing Equations
6. f all the elements are balanced except one and there is an even number of atoms of that element on one side and an odd number on the other, double the first factor and rebalance.
7. Remember that an equation can never be correct if there is a wrong formula written in it.
8. Always us the smallest possible whole numbers to balance the equation.
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Copper sulfide + oxygen gives copper oxide + sulfur dioxide CuS + O2 → CuO + SO2 As written, the copper and sulfur atoms are balanced with one each but there are two oxygen atoms in the factors and three in the products. Put a 2 in front of the CuS and balance the equation. 2CuS + 3O2 → 2CuO + 2SO2 Try this technique on the equation for the burning of acetylene, C2H2. C2H2 + O2 → CO2 + H2O
C—12
Oxidation Numbers for Polyatomics
The Dynamic Duo
IIA IVA VA VIA VIIA
BO3-3 CO3
-2 NO3-1 --- ---
SiO4-4 PO4
-3 SO4-2 ClO3
-1
AsO4-3 SeO4
-2 BrO3-1
TeO4-2 IO3
-1
C—13
Flow Chart for Formula Writing
The Dynamic Duo
Symbol Only
Use Oxida-tion
# Chart and 5
Steps for
Matter
Mixture
Compound
Element
No Formula
Write the Symbol with
the Sub-
Binary
Use Number Prefixes in Name as
Subscripts
Memorize
Acid in
Dia- Yes No
No Yes
C—14
Flow Chart for Naming Compounds
The Dynamic Duo
C—15
Chem Country Hall
(An analogy for Le Chatelier's Principle) Welcome to Chem Country's favorite dance hall. It features unusual con-struction. The front doors open to a seating gallery, complete with water coolers and fans. To get on the dance floor, the couples must pass through a revolving door, and dancing must be done as couples. The dance floor and the seating gallery are both air-conditioned. On one particular night, 80 boys and 60 girls arrive as singles. After a bit, the dance floor is filled to its capacity of 45 couples and equilibrium is
established. When a couple stops dancing, it goes back to the reception room through the revolving door to take their place. A dynamic equilibrium is established. Now let's consider what scenarios might disturb this equilibrium: fans + air-conditioning air- conditioning 80 boys + 60 girls 45 couples + heat· 1. Some couples sneak out of a rear door adjacent to the dance floor. 2. Some couples sneak into that locked door. 3. Some extra single boys arrive at the front door anxious to dance and pile in. 4. The air-conditioning breaks down everywhere in the hall. 5. Someone turns the thermostat way down in the seating gallery. 6. The revolving door is oiled allowing twice as many people per minute to pass through. (Taken from the Journal of Chemical Education, date unknown.)
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C—16
Sodium Chloride Dialog
(Atoms stand about 3 feet apart) He atom: “Hello Miss Chlorine” She atom: “Hello Mr. Sodium” He: “How are you?” She: O.K., except I feel a bit unstable. How about you? He: About the same, thank you. It must be the season for unstableness, I guess. She: I guess so. My chemist said I might feel more stable if I would fill up my outer shell. He: Really? That’s what Argon said to me the other day. He has a full outer shell you know. She: Yes I know. He’s just like that noble Miss Neon. You know, they hardly ever asso-
ciate with the rest of us. He: Not only that, but those inert nobles just don’t realize how hard it is to pick up even
just one electron these days. And I need seven! She: Really? Gee, seven is a lot. I’m luckier I guess because I only need one. He: You are lucky! She: Seven (thoughtfully point to he)….One (thoughtfully point to self)…Say I have an
idea! He: What? She: If you wouldn’t mind, you could give me your one lone outer electron; and then I
could be stable. He: Big deal!! It helps you but what about me? Do you plan on giving me all eight? She: No..but..well, your next closest shell would become your outer shell and its already
full. He: That makes sense (thoughtful). That’s a great idea (excited). Let’s try it!!
(overjoyed) (Exchange electron, he drops outer shell, then show charge signs.) She: That cured my unstableness. How about you?
The Dynamic Duo
C—17
Sodium Chloride Dialog
He: I’m stable, but I still don’t feel quite right. She: Now that you mention it, neither do I. I feel sort of (pause) charged up. He: I do took but just the opposite from you, of course. She: I guess my idea for becoming stable wasn’t so good, Now what do we do? He: I don’t mean to be forward but do you notice how the charged feeling leaves as
we……..well……..(embarrassed)………move closer? (He atom moves toward she atom, then atoms touch and signs disappear) She: Hey, it worked! The charged feeling is gone but now we can’t break away! He: I guess we will stay together like this for a long time. She: Yes……………..until energy doth us part!
THE END
The Dynamic Duo
C—18
Atomic Theory Poems
(from handouts given sometime in the past from an unknown source) Ode To Quantum Mechanics Listen, my children, and you shall hear of quantum mechanics theory, still held high in revere. The descriptive equation is so complex That even sophisticated computers it has been known to vex. The real problem with this topic is that by the time That you and I understand it, it may be past its prime. So why bother to consider it? I hear—and ask in return, What better do we have—about atoms to learn? A=And should you ever—and you never know when— Have a burning desire for an electron rated “10” Where would you look, with this world such a mess? Where in space might you find that electron’s address? The Aufbau Process With an s, and three p’s, and five d’s, You can build any atom you please, There’s no need for tools, Just follow the rules, And fill up the pods with the peas. Meneleev Replies (Posthumously) Dimitri shall have the last work. Most Aufbau is somewhat absurd. Each energy level can go to the devil If the chemical meaning’s not heard. Rutherford (1911) Alpha particles tend to pass through A piece of gold foil, yet a few Bounce back, whence they came and bear most of the blame For Rutherford’s nuclear view. Wave Particle Duality (1924) A rock is a rock and a wave is a wave, At least that is how things ought to behave So it tends to annoiy me When Louis de Broglie Claims a rock’s both a rock and a wave.
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C—19
Atomic Theory Poems
The Heisenberg Uncertainty Principle (1926) An electron’s momentum you’d think Could be measured as quick as a wink, But when you know to a tee The x, y, and z The momentum goes right down the sink. The Pauli Exclusion Principle (1925) An electron complained to young Pauli “You say that you will not allow me, To line up my spin With my orbital twin, Why is it you treat me so foully?” The following song, with lyrics by JJ Thomson was uncovered by Bruce Berman. The tune is “Darling Clementine. Ions Mine In the dusty laboratory ‘mid the coils and wax and twine, There the atoms in their glory Ionize and recombine. Chorus: Oh My Darlings! Oh My Darlings! Oh my darling ions mine! You are lost and gone forever When just once you recombine! In a tube quite electrode less They discharge around a line, And the glow they leave behind them Is quite corking for a time. And with quite a small expansion, 1.8 or1.9 You can get a cloud delightful Which explains both snow and rain. In the weird magnetic circuit See how lovingly they twine, As each ion describes a spiral Round its own magnetic line.
The Dynamic Duo
C—20
Atomic Theory Poems
Ultra-violet radiation From the arc of glowing lime Soon discharge a conductor If it’s charged with minus sign. Alpha rays from radium bromide Cause a zinc blende screen to shine Set it glowing, clearly showing Scintillations all the time. Radium bromide emanation Rutherford did first devine Turns to Helium, then Sir William Got the spectrum—every line.
The Dynamic Duo
D—1
The Dynamic Duo
D—2
The Dynamic Duo
Just How Many In A Mole?
Calculations Must Include Your Work, Including Units. Procedure A: How Many Water Molecules Are In A Mouthful Of Water? Fill a paper cup with water. Wipe off the outside. Find the mass and record. Drink one mouthful of water. Wipe off the outside. Reweigh the paper cup and water and record its mass. Throw away the cup. Data: Mass of paper cup and water before drinking _________ Mass of paper cup and water after drinking. _________ Calculations: Mass of water swallowed _________ Moles of water swallowed. _________ Number of water molecules swallowed. _________ Procedure B: How Many Aspirin Molecules In An Aspirin Tablet? Tare a condiment cup. Add an aspirin and reweigh. Record the mass. Return the aspirin to the container. Aspirin's chemical name is acetylsalicylic acid and the formula is C9H804. Data: Mass of the aspirin tablet. _________ Calculations: Moles of aspirin in tablet _________ Number of aspirin molecules in tablet. _________
D—3
The Dynamic Duo
Molarity
This Group Is To Make A _______ Molar Solution Of NaCl And Water. Your Volumetric Will Hold _______________ml. Show Calculations Here For Determining How Much NaCl To Mass __________Grams Of NaCl Stamp Here For Showing Teacher Mixed Solution Teacher: Each lab group had a different container to use instead of a volumetric. We used recycled plastic bottles. We measured the desired volume of water and poured into bottle. A mark was made at this point with a permanent marker
D—4
The Dynamic Duo
Massing Moles
1. Weighing A Mole: Name Of Substance Go to your lab station and mass out a formula weight of your substance into given paper cup. Pour into Zip-lock bag and label. Show your calculation. Show Work Here: Formula Weight: _________ 2. Determining Number Of Moles In Your Substance At your lab station there is a bag with a substance In It. The weight of the bag is given. Using the balance determine the weight of the substance In the bag and the number of moles of substance. Show Calculations Here: Formula Weight _________ Grams Of Substance ________ Moles Of Substance _________ 3. Calculating Mass From Density, Moles And Molecules In your basket are num-bered graduated cylinders containing liquids. They are labeled. Formula __________________ Density __________________ Add Up Formula Weight For Your Substance Show Work:
D—5
The Dynamic Duo
Massing Moles
Read Volume. Calculate the mass from the density and the volume. Show Calculations: Mass:___________ Calculate the number of molecules in the compound and number of carbon atoms. Show Work: Number of Molecules __________ Teacher: • Samples Of Compounds Are At Each Lab Station. • The Weight Of The Plastic Bag Is Given On The Bag. • The Name Of The Compounds Is Given. Ideally you would set up 12 different lab stations so that each lab group would have differ-ent substances. You would want to use both elements and compounds. Examples of substances that you could use: Chalk (calcium carbonate), salt (sodium chloride), sand (silicon dioxide), sulfur, aluminum Foil (Aluminum), table sugar (glucose), copper, iron (steel wool) baking soda (sodium bi-carbonate) Examples of liquids: Ethyl alcohol, methyl alcohol, isopropyl alcohol, glycerin, distilled water
D—6
The Dynamic Duo
Rainbow Tube
Background: This activity can be used to introduce the concept of pH indicators. Vinegar is a dilute so-lution of acetic acid (HC2H3O2). Sodium Carbonate (washing soda) has a pH greater than 7. The indicator used is a universal indicator. It is which is a mixture of indicators and has a distinctive color at each pH. The sodium carbonate is more dense than the vinegar. It sinks and neutralizes the vinegar as it moves down the column. The indicator in the vinegar indicates how the pH is changing. Materials: Clear plastic straw glued at one end with hot glue gun, dilute vinegar + indicator solution, sodium carbonate (washing soda solution), 96-well plate Safety: Wear Goggles. Sodium carbonate has a pH greater than 7. Keep away from eyes and skin. Tube can be discarded in regular trash after a few days. Directions: 1. Write initials on prepared straw (glued shut on one end) with permanent pen. Set upright in 96-well plate. 2. Fill the straw nearly full of the vinegar-indicator solution with thin-stem Beral Pi-pette. Vinegar is dilute acetic acid (HC2H3O2). 3. Deliver the solution down the side of the straw so that no air bubbles form. Add 2 to 3 drops of the Na2CO3 solution to the straw with thin-stem Beral pipette. Wait 10 to 15 seconds for this dense solution to sink, then add 2 to 3 drops more. Then add 3 more drops. Na2CO3 has a pH > 7. It is more dense than the vinegar solution, so it sinks to the bottom of the tube. 5. Hold the straw vertically to watch the colors. 6. The indicator used is a mixture of many indicators. The color change is indicated as follows: We will use Yamada's Universal Indicator It exhibits the ROY G BIV color sequence in the pH range 4-10 Color: red orange yellow green blue indigo violet pH: 4 5 6 7 8 9 10 7. Have the teacher glue the other end. Store upright and observe over a week.
D—7
The Dynamic Duo
Rainbow Tube
Questions: 1. Describe what you see. 2. What caused this reaction? 3. After the prepared straw sits for awhile, how does it look? Directions for Teacher Materials: 1. Transparent plastic straws – Sam’s is a good source. Glue at one end with hot glue gun. Let it sit for a few days. 2. A saturated solution of Na2CO3 (washing soda). WARNING: THIS IS A STRONG BASE. 3. A dilute vinegar solution - 100 ml per liter of distilled water. 4. Prepare the vinegar-indicator solution by adding 50ml indicator to 250ml of pre-pared vinegar solution. 5. You may purchase universal indicator or prepare Yamada indicator. To prepare 200 ml Yamada Indicator: Dissolve 0.005 g thymol blue, 0.012g methyl red, 0.060g bromthymol blue, and 0.10g phe-nolphthalein in 100 ml ethyl alcohol. Add 0.01M sodium hydroxide until the solution is green and dilute to 200 ml with distilled water.
D—8
The Dynamic Duo
Types of Reactions
1. Place two small pieces of zinc in a Petri dish. Add one dropper full of 0.1 M lead ace-tate. Observe. Let stand until the end of the period. Observe. Empty into colander in sink. Rinse Petri dish with tap water and then with distilled water.
Observation: ______________________________________________________________________________________________________________________________________________ Equation: _______________________________________________________________ Demonstrations: 2. Heat a beaker containing one to two centimeters of water to boiling. Cover with a glass plate and boil until beaker is filled with steam. Inset a burning splint into the steam and observe the reaction. Observations: ___________________________________________________________ 3. Ignite a small piece of magnesium ribbon over a Bunsen Burner until it ignites. Do not look at the flame. Equation: _______________________________________________________________ 4. Immediately transfer the product into the steam and return the glass cover. Add several drops of phenolphthalein solution to the water. Observations: ___________________________________________________________ Equation: _______________________________________________________________ 5. React sodium bicarbonate (baking soda) with acetic acid (vinegar) in beaker. Cover.. Equation: _______________________________________________________________ 6. Ignite a splint. Insert into beaker and observe. Observations: ___________________________________________________________ 7. Ignite another small piece of magnesium ribbon with Bunsen burner holding with tongs as before. Equation: _______________________________________________________________ 8. Quickly insert product into beaker. Turn out lights. Observe. Observations: ___________________________________________________________ Equation: _______________________________________________________________
D—9
The Dynamic Duo
Boiling Water in a Syringe
Materials: Syringes with stoppers to close in basket, warm water- mix tap water in beaker with water from coffee pot . Directions: 1. Have a member of each team come up and pull about 5 ml warm water into syringe. 2. Cover the end with stopper. 3. Pull the plunger out being careful not to pull entirely out. 4. Remove stopper. 5. Push the plunger back in. 6. This may cycle can be repeated. 7. Discuss what is happening and how this relates to Gay Lussac's Law. Discussion: 1. What is the temperature of the boiling water? Feel the syringe. 2. What is a boiling point? 3. What is happening to the temperature of the liquid during the boiling process?
D—10
The Dynamic Duo
Experiencing a Chemical Reaction
Materials: 1 pint ziplock bag, sodium bicarbonate. calcium chloride. methyl red Procedure: 1. Take one ziplock bag. 2. Put in one teaspoon sodium bicarbonate and one teaspoon calcium chloride. 3. Mix. Observe. 4. Measure one small condiment cup of methyl red. 5. Add to ziplock bag. Immediately squeeze out excess air an seal bag. Turn bag from
side to side to mix. 6. Feel. Observe. Note temperature, color etc. 7. After about five minutes, empty bag into sink and put empty bag in trash. Observations: Conclusions: Equation:
D—11
The Dynamic Duo
Boiling Water in a Paper Cup
Materials: Bunsen burner, ring stand, ring, wire gauze, striker, tongs, unwaxed paper cup, water Demo: Take an empty unwaxed paper cup and heat In the flame of a Bunsen burner. Directions: • Take an unwaxed paper cup and fill 1/4 full of tap water. • Put on wire gauze on ring and heat until water bolls. Observations: 1. Describe what happened to the cup. 2. Paper Is a flammable substance which has to be heated to Its kindling temperature be-fore It burns In air. It has a low heat capacity. It requires little heat to raise the tempera-ture. Is the heat capacity of water high or low? 3. When there Is water In the cup, what Is the highest temperature the cup can be? 4. Therefore you know that the kindling temperature of the cup Is above what tempera-ture? 5. When the temperature of a substance Increases the motion of Its particles Increases. Intermolecular forces must be overcome. What kind of Intermolecular forces does water have? Strong or weak?
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The Dynamic Duo
Voice Activated Chemical Reaction
Description: A liquid changes color as students "speak" to the flask. Materials: 1 500-mL Florence Flask, phenol red indicator 1M NaOH Procedure: Add two drops of phenol red indicator to 250 mL water. Add 1M NaOH a drop at a time until it turns red. Pass flask around the room and have students talk into the flask. Have a story about the person with the sexiest voice, etc wilI ,affect the magic water. Discussion: Eventually the CO2 from the student's breath will produce enough acid in the solution to cause the color of the indicator to change. This activity can be used to introduce the concept of acids and bases. The intended audi-ence is the 5th grade through high school. CO2 (g) + H2O (l) → H2CO3 (aq) Reference: Summerlin, Lee R. and James L. Ealy, Jr., Chemical Demonstrations: A Sourcebook for Teachers, American Chemical Society, Washington, D.D., 1985.
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The Dynamic Duo
Soda Can Crunch
Context: Gas behavior, pressure, temperature, and volume changes. Materials: aluminum soda can, tongs, Bunsen Burner, Large pan cool water, striker, 10 ml graduated cylinder Safety: Be careful with Bunsen Burner and holding the soda can with tongs to heat. Procedure: 1. Pour about 5 ml tap water into an empty soda can. 2. Boil to water by holding can in Bunsen Burner with tongs until you see a steady stream of water vapor. 3. Quickly invert the can into a pan of cool water. Questions: 1. What phase changes (from what to what) did the water go through? 2. What happened to the volume of the gas in the can? 3. What happened to the pressure in the can? (increase or decrease? 4. Was energy taken in or given off? 5. How did the pressure cause the dramatic end? Explanation: When the can is heated the water turns to steam. It is a gas. It fills up the entire can. When the can is suddenly cooled the steam turns to water – a phase change. The water has occupies much less volume. The volume decreased. The pressure in the can decreased. The pressure in the can is now less than the pressure outside the can.
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The Dynamic Duo
Marshmallow in a Syringe
Materials: 60 ml syringe with Luer Lock, a mini-marshmallow Procedure: 1. Remove the Luer lock from the syringe and pull out the plunger. 2. Put the marshmallow on top of the plunger and insert back into the syringe. Do not mash marshmallow. 3. Put Luer Lock on tip of syringe. 4. Gently pull the plunger back and forth and observe the marshmallow. 5. BE CAREFUL NOT TO PULL THE SYRINGE APART. Explanation: The marshmallow is filled with air. When you decrease the volume, you increase the pressure. – Boyles Law
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The Dynamic Duo
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The Dynamic Duo
Electroplating Copper
Materials: 1 film canister 3 slits in top 1 plastic strip 2 cm by 7 cm. 1 copper strip 1.5 cm by 6 cm. copper plating solution 9 volt battery 1 red and 1 black connectors, insulated wire with small alligator clips at each end 1 iron nail or other metal object Buret clamp ring stand Acetone (optional) Copper Plating Solution: 200g of CuSO4. 5H2O, 17.2 ml of conc. H2SO4, 8.25 ml of 0.1M HCI. Dilute to 1 liter. Safety: Wear safety goggles and aprons. The plating solution is very acidic. Neutralize with bak-ing soda if spilled. Stabilize the film canister by using Buret clamp to attach to ring stand. Use acetone to clean nail in well -ventilated area, under hood if possible. Reuse acetone. Procedure: 1. Clean object to be plated with acetone under the hood. This can be a nail or another
metal object. 2. Assemble lid of cell. Plastic strip is in middle and copper strip to one side and nail or
object in the other. 3. Attach bottom of film canister to ring stand with Buret clamp. 4. Fill canister 3/4 full of copper sulfate solution and tightly seal with assembled lid. 5. Connect battery to cell with leads. Connect the object to be plated to the positive terminal of the battery and the copper strip to the positive terminal of the battery. 6. Wait 1 minute. Carefully disconnect battery and remove lid of cell. Observe object (nail) plated. Record Observations: Remove plated object. Rinse lid with distilled water in water bottle. Pour back copper plating solution into original container for recycling.
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The Dynamic Duo
Testing Antacid Tablets
Introduction Recently there have been numerous advertisements for antacids on television. These products are used to neutralize stomach acids. How do these antacids work? Most ant-acids usually contain carbonates, bicarbonates, or hydroxides. All act as bases and have a neutralizing effect on acids. The carbonates and bicarbonates also produce CO2 when they react with acids. This buildup of gas in the stomach causes the expulsion of the gas, the burp. This also provides relief. Many antacids contain calcium compounds are not very soluble in water. This increases the possibility of an antacid being absorbed into the bloodstream. If too much base is absorbed into the bloodstream a condition called alkalo-sis occurs. In this experiment, you will use HCl to neutralize the antacids. You will determine which antacid is most effective in neutralizing the acid. Real stomach acid is HCl with a pH range of 0.9 to 1.5. We will use 1.0 M HCl in this lab. The process of gradually adding an acid to a base or a base to an acid until neutralization occurs is called titration. The number of milliliters it takes to neutralize the acid or base is carefully measured. An indicator is used to show the endpoint, the point at which neutrali-zation occurs. Indicators are organic compounds, which may be different colors at a dif-ferent pH. The colors at a different pH vary according to the indicator. It is important that the color change in the indicator can be detected when the pH is changed. Crystal Violet has been chosen for this titration. Below pH 0.8 it is yellow. Between pH 0.8 and pH 1.1 it is green. Above pH of 1.1 it is blue. Since the pH range of the stomach is 0.9 to 1.5, this is a good indicator to use. What you are trying to do with the antacids is to get the pH of the stomach back to a normal pH range of 0.9 to 1.5. In this lab, the more milliliters of HCl it takes to neutralize the antacid, the more effective the antacid is in neutralizing the acid in the stomach. In a standard neutralization an acid + base → salt + water Example: NaOH + HCl → NaCl + HOH Carbonates + bicarbonates + acid → a salt + carbon dioxide + water This is also a type of neutralization. NaHCO3 + HCl → NaCl + H2CO3 ↓ H2O + CO2 Materials: 1.0 M HCl, water bottle filled with distilled water, 0.04 gram samples powdered antacids, 1 ml syringe, microstopcock (Flinn # AP9159), microtip Beral-type pipet, scissors, condiment cup for waste, 50 ml Erlenmeyer flask, crystal violet indicator in pipet, stirring rod, weigh-
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The Dynamic Duo
Testing Antacid Tablets
ing dish, balance accurate to .01or .001 gram, ring stand, clothespin holders or 96 well plate and microchem support stand (Flinn # AP9013) . Safety: Wear goggles at all times. HCl is corrosive. If spilled, neutralize with baking soda. Procedure 1. Mass 0.04 gram sample of powdered antacid in weighing dish or 1 oz condiment cup. 2. Transfer dry powder to a 50 ml Erlenmeyer flask or leave in condiment cup 3. Add a few ml of water from water bottle to rinse the weighing dish and add this to the
Erlenmeyer flask. Repeat rinsing a second time. All of the solid may not dissolve. The antacid contains some “fillers” that may be insoluble. All of the active ingredients will dissolve as HCl is added.
4. Add 3 drops of crystal violet indicator. Note the color. This is a basic solution. 5. Cut off the tip and the top of the microtip Beral-type pipet to form a funnel. 6. Put tip of microtip Beral-type pipet on the end of the microstopcock and attach the
stopcock to the bottom of the syringe. 7. Remove the plunger from the syringe and put the funnel you formed from the microtip
pipet on top of syringe. 8. Steps 5 ,6,and 7 may have been done for you. Attach the syringe to ring stand with the
clothespin holder. 9. Close stopcock. Place waste condiment cup underneath syringe. 10. Fill the red dot syringe buret with 1M HCl with a thin-stem pipette. Check to see that
there are no bubbles. Allow some of the solution to drain into the waste container to fill the stopcock and the tip with solution. Refill the syringe buret until the HCl level is at or just below the 1.00ml mark. Record the initial reading of HCl .
11. Place the Erlenmeyer flask or condiment cup with the antacid and indicator beneath tip of stopcock. Open stopcock so that one drop of acid comes out at a time. Gently swirl Erlenmeyer flask. Add HCl until the color remains a definite blue with a tinge of green. Immediately close stopcock and take reading. Record as final reading of acid.
12. Empty contents of Erlenmeyer flask into waste container. Rinse several times with distilled water until clean.
13. Repeat procedure with another antacid.
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The Dynamic Duo
Testing Antacid Tablets
Report Page Data Table
Questions: What was the color of the indicator in the basic solution? __________________________ What was the color of the indicator at neutralization?______________________________ Which antacid was the best acid neutralizer and why? ____________________________ ______________________________________________________________________________________________________________________________________________ What was the main ingredient of Tums? _______________________________________ Write and equation of the reaction of Tums with HCl.
Trial #1(Name) #2(Name) #3(Name)
Initial volume of acid
ml
ml
ml
Final volume of acid
ml
ml
ml
Volume of acid reacted
ml
ml
ml
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The Dynamic Duo
Vitamin C Content of Fruit Juices
Introduction Vitamin C, ascorbic acid, is produced naturally by plants and animals except for humans. A deficiency in Vitamin C causes a disease known as scurvy, the symptoms of which are bleeding, spongy gums and a tendency to bruise easily. Because our body has a limited ability to store Vitamin C, it is necessary to eat foods, which contain Vitamin C as part of our daily diet. Foods that contain significant amounts of Vitamin C include citrus fruits and some green plants such as spinach and green peppers. The recommended Dietary Al-lowance of vitamin C is 60 mg per day.
Fruit juices naturally contain other acids such as citric acid in addition to ascorbic acid; therefore, an acid-base titration cannot be used to determine the amount of ascorbic acid, Vitamin C. In this lab you will determine the amount of Vitamin C (ascorbic acid) in 1 serving (6 oz) of orange juice, apple juice or other Vitamin C containing juices by titration of the ascorbic acid in the juice with an iodine solution. The chemical reaction involved is the oxidation of ascorbic acid by iodine to dehydroascorbic acid. The end point of the ti-tration will be determined by the formation of the starch-iodine blue-black complex when an excess of iodine becomes present. As long as ascorbic acid is present, the iodine is converted to the colorless iodide ion. Once the ascorbic acid has all reacted, the iodine forms the blue-black complex with the starch indicator. C6H8O6 + I2 → 2 H+ + 2I- + C6H6O6 Vitamin C Oxidized form of vitamin C (Ascorbic acid) (Dehydroascorbic acid) The micro-scale titration will be done using 1 ml syringes as burets. The concentration of the iodine solution will be determined by titrating a standard solution of ascorbic acid, which contains 1 mg ascorbic acid per ml of solution. From this titration’s data, you will calculate the mg Vitamin C equivalent to one ml of the iodine solution. Calculations are simplified because iodine and ascorbic acid react in a 1:1 mole ratio. If 0.72 ml iodine were used to titrate 0.85 ml Vitamin C then: (equation 1)
= 1.2 mg Vitamin C/ml I2 solution
This iodine solution will then be used to titrate the fruit juice. If 0. 50 ml of iodine solution was used to titrate 0.81 ml of orange juice (OJ), the mg Vitamin C per 6 oz. serving of juice will be calculated using the information that 1 oz equals 30 ml. (equation 2)
= 122 mg Vitamin C per serving
1 mg Vitamin C 0.85 ml Vitamin C used
1 ml Vitamin C solution 0.72 ml Iodine solution used
1.2 mg Vit C 0.50 ml I2 30 ml OJ 6 oz
1 ml I2 0.81 ml OJ 1 oz OJ 1 serving
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The Dynamic Duo
Vitamin C Content of Fruit Juices
Materials (Per Lab Group): 1 ml Syringes Standard ascorbic acid solution (1mg/ml) “Poor Man’s” buret micro stopcock Iodine solution 1 microtip Beral-type pipet Starch solution thin stem Beral-type pipets Fruit Juices: orange, apple, lemon, white, grape microchem support stand or ring stand 96 well Reaction Plate 1 25 ml Erlenmeyer Flask waste container or condiment cup Safety Precautions: Goggles and aprons must be worn. The iodine solution may stain hands or clothing and can irritate skin. Ascorbic acid is not considered hazardous, however, students should wash their hands thoroughly after handling. Food items, once brought into a lab, are con-sidered chemicals and, as such, should not be ingested.
Disposal: The small amounts of the solutions may be disposed of down the drain. Any left over io-dine solution should be saved for use in future labs. Procedure 1. Fill the green dot syringe with the standard ascorbic solution. Set the waste container
under the syringe and dispense the solution into the waste container until the liquid level is on or just below the 1.00 mark. Read the volume of ascorbic acid solution and record it in the data table as the initial volume of ascorbic acid.
2. Place the 25 ml flask under the ascorbic acid syringe. Allow about 0.70-0.80 ml of the solution to flow into the flask. Read the level of the solution in the syringe and record as the final volume of ascorbic acid.
3. Place the microchem support in a corner well of the 96 well reaction plate. Place the syringe buret (purple dot) in the support. Another option, attach clothespin microchem support to normal ringstand. Refer to photographs in handout.
4. Place the syringe buret (purple dot) in the microchem support. Fill the syringe with the iodine solution using a thin-stem pipet. Check to see that there are no bubbles. Al-low some of the solution to drain into the waste container to fill the stopcock and tip with the solution. Refill the syringe with iodine so the level is on or just below the 1.00 mark. Read the volume of iodine and record in the data table as the initial volume of iodine.
5. Add 2 drops of starch to the ascorbic acid in the flask. Swirl to mix. 6. Place the flask under the iodine (purple dot) syringe buret. Add iodine drop by drop
with swirling to mix until the solution turns blue-black and remains blue-black after mix-ing. Read the level of the solution to the nearest 0.01 ml and record as the final vol-ume of iodine.
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The Dynamic Duo
Vitamin C Content of Fruit Juices
7. Empty the flask and rinse several times with distilled water. 8. Refill the syringes and repeat procedures # 2-7 for two more trials. 9. Fill the pink dot syringe with distilled water and allow it to flow out into the waste con-
tainer several times. Then fill the syringe with the juice to be tested and allow the juice to flow into the waste container.
10. Fill the syringe with the juice. Set the waste container under the tip and allow enough juice to flow through so the level is on or just below the 1.00 ml mark. Read the vol-ume of the juice and record in the data table as the initial volume of juice.
11. Place the 25ml flask under the juice syringe. Allow about 1.0 ml of the solution to flow into the flask. Read the level of the solution in the syringe and record as the final vol-ume of juice.
12. Add 2 drops of starch and a few ml of distilled water to the juice in the flask. Swirl to mix.
13. Place the flask under the iodine buret. Add iodine drop by drop with swirling to mix until the solution turns blue-black and remains blue-black after mixing. Read the level of the solution to the nearest 0.01 ml and record as the final volume of iodine.
14. Refill the syringes, empty, rinse the flask, and repeat procedures # 12-14 for two more trials.
15. Empty the juice syringe into the waste container. Fill the syringe with distilled water and allow it to flow out into the waste container several times. Then fill the syringe with the another juice to be tested and allow the juice to flow into the waste container.
16. Repeat the titration as above with other juices. The standardization steps do not need to be repeated as long as you are using the same syringe buret.
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The Dynamic Duo
Vitamin C Content of Fruit Juices
Report Page
Data Table Standardization of Iodine
Calculations: 1. Calculate the mg Vitamin C equivalent to 1 ml of the Iodine solution. (See equation 1.)
Show work below for each trial and place your answer in the data table above. Calcu-late the average for the 3 trials and place your answer in the data table above.
TRIAL # 1 2 3
Initial volume Ascorbic acid ml ml ml
Final volume Ascorbic acid ml ml ml
Volume ascorbic Acid used ml ml ml
Initial volume Iodine solution ml ml ml
Final volume Iodine solution ml ml ml
Volume iodine Solution used ml ml ml mg Vitamin C equivalent to 1 ml I2 Average mg Vitamin C equivalent to 1 ml I2 mg
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The Dynamic Duo
Vitamin C Content of Fruit Juices
Fruit Juice Data Table
Calculations & Questions Continued: 2. Calculate the mg of Vitamin C found in a 6 oz. Serving of each juice. (See equation # 2) Show
work below and place your answers in the data table above. 3. Which juice contains the most Vitamin C per serving? ___________________________ 4. Was this your expected result?______ Explain why this might be true. (Hint: Read the label on
the juice container.)
Kind Of Juice Orange Juice Apple Juice Lemon Juice Initial volume Juice ml ml ml Final volume Juice ml ml ml ml juice used ml ml ml initial volume iodine ml ml ml Final volume Iodine ml ml ml ml iodine used ml ml ml mg Vitamin C per 6 oz serving mg mg mg
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The Dynamic Duo
Vitamin C Content of Fruit Juices
Preparation Of Solutions: Standard ascorbic acid solution: Dissolve 0.10 grams of ascorbic acid in enough dis-tilled water to make 100 ml of solution. This solution should be made fresh each day. An alternative method is to make the ascorbic acid by crushing a 100 mg Vitamin C tablet and adding enough water to make 100 ml of solution. One ml of these solutions will con-tain one milligram of ascorbic acid. Iodine solution: Fill a 250 ml volumetric flask about ½ full with distilled water. Dissolve 0.10 g potassium chlorate and 10.00 g of potassium iodide in this water. Add 25 ml 1M sulfuric acid. Swirl to mix. Then add 0.10 g of iodine crystals and dissolve. Add enough distilled water to make 250 ml of solution. The iodine is slow to dissolve. Don’t plan to make it at the last minute. Starch solution: Place about 100 ml of distilled water in a beaker. Generously spray with spray starch (from the grocery store) for a minute or so. Stir and allow foam to dis-perse. The solution should be translucent or milky looking. If necessary spray a second time. (An alternative is to boil water, make a paste of powered starch and cold water and stir the paste into the boiling water.) Teaching Tips: 1. Remove the plunger from the syringe. Fit the stopcock on the bottom of the syringe.
Cut the tip from a microtip pipet about 0.5 cm above the tapered end and fit the tip on the end of the stopcock.
2. The amounts of Vitamin C in different kinds of juice may prove to be the same be-cause of the addition of ascorbic acid as an ingredient. Read the labels and chose those which do not have added Vitamin C.
3. The orange juice used should be low pulp or strained so that the pulp does not clog the stopcock. Baby food juices provide a convenient source of no pulp juice: however most have added ascorbic acid causing the various juices to have approximately the same amount of Vitamin C.
4. Juices other than apple, orange, or lemon can be used in this experiment provided they are light in color. Using darker colored juices, such as grape juice, will make it difficult to determine the end point of the titration.
5. The Vitamin C content of foods decreases if stored uncovered at room temperature or higher temperatures. Vegetables cooked in water lose much of their Vitamin C con-tent.
6. An extension of this experiment could study and graph the decline in Vitamin C con-centration left open in the classroom for a period of days.
7. Another extension could compare the Vitamin C content in canned, frozen, bottled and fresh squeezed orange juice.
8. The cost of Vitamin C from different sources could be studied. Adapted from a lab by Bro. Carmen V. Ciardullo in Microaction Chemistry V 2 published by Flinn Scientific Inc
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The Dynamic Duo
Boyle’s Law Purpose: In this lab you will measure the volume of a confined gas in a closed syringe inside a 0.5 liter plastic soft drink bottle. Pressure will be increased by using a Fizz-Keeper©. . Materials: 1 Disposable 3 ml syringe, modified 1 Syringe Tip Cap Small amount silicone lubricant (Stopcock Grease) 1 Fizz-Keeper ©. 1 plastic soft drink bottle, 0.5 liter Directions: 1. Remove the plunger from the syringe and apply a thin application of silicone lubricant
to the black part of the plunger. Reinsert the plunger into the syringe. 2. Adjust the position of the plunger to the 3.0 ml mark. 3. Place the syringe cap on the syringe trapping 3.0 ml of air in the syringe. 4. Place the syringe in the soft drink bottle and screw the Fizz-Keeper © on the bottle.
Record the beginning volume as 3.0 ml. 5. Increase the pressure in the bottle by pumping the Fizz-Keeper © 10 times. Read the
volume of the air in the syringe. 6. Pump 10 more times and record the volume. Continue pumping 10 time and reading
the volume for a total of 10 volume readings. 7. Plot a graph of pressure (# of strokes) vs. volume. Data Table:
Teachers Guide Purpose: To give students a first-hand experience with Boyle’s Law Scope & Sequence: Can be used to 1ntroduce Boyle’s Law in the unit on gas laws or to follow - up shortly after the textbook introduction. Preparation & Tips: Cut off the “wings” at the top of each syringe. Fizz-Keepers may be purchased at discount stores. They are also available from Flinn. Hazards: Release pressure by twisting the cap slowly at end of the measurements. Disposal: None. Keep syringes & syringe caps for next year. Reference: Rohrig, Brian. 39 FANTASTIC EXPERIMENTS WITH THE FIZZ-KEEPER
PRESSURE (#STROKES) 0 10 20 30 40 50 60 70 80 90 100
VOLUME OF AIR 3.0
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The Dynamic Duo
Acid Deposition Simulation
Background: This lab provides students the opportunity to observe noxious oxides that are a major fac-tor in pollution that otherwise could not be observed in a high school laboratory. Optional exercises permit the student to design his ova environment and to be able to observe fac-tors that effect pollution. The atmosphere is a warm blanket that helps to maintain conditions suitable for life as we know it. Oxygen is one of the most important elements in the atmosphere because organ-isms need oxygen to stay alive. Oxides are binary (two elements) compounds containing oxygen and one other element. They are abundant in the earth's crust. Three major categories of oxides that are also air pollutants are: 1. Carbon oxides (CO2 and CO) Carbon dioxide and carbon monoxide are produced by the combustion of organic materi-als, primarily gasoline and other fossil fuels. 2. Oxides of sulfur (SO2 and SO3) Sulfur compounds, mostly S02, are among the most unpleasant and harmful of the com-mon pollutant gases. About 80 % of all the S02 generated comes from the combustion of fossil fuels. They are also produced by burning coal and from oil refineries. These com-pounds form acids in moist air.
S (s) + O2 (g) → SO2 (g)
Sulfur dioxide may be oxidized to S03 by any of several pathways.
2 SO2 (g) + O2 (g) → 2 SO3 (g)
Once SO3 is formed it dissolves in water droplets, forming sulfuric acid.
SO3 (g) + H2O (l) → H2SO4
This what happens when fuel containing sulfur is burned. 3. Oxides of nitrogen (NO2, etc.) come from fuel burning (power plants and automobiles).
In all combustion reactions in the air, nitrogen combines with the oxygen.
N2 (g) + O2 (g) → 2 NO (g) Nitric oxide (NO) reacts readily with O2 to form NO2 when exposed to the air. 2NO (g) + O2 (g) → 2NO2 (g)
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The Dynamic Duo
Acid Deposition Simulation
When dissolved in water, N02 forms nitric acid. 3 NO 2(g) + H2O (l) → 2 HN)3 (aq) + NO (g) The combustion in the automobile is the worst offender. At the high temperatures of the automobile engine NO is formed. NO acts as a catalyst for ozone destruction and is in-volved in the production of smog in addition to the acid rain production. The amounts of nitrous oxides can range from 1 gram per km (kilometer driven) for a new passenger car to over 20 grams per km (kilometer driven) for an old diesel truck. The anthropegenic (man-made) nitrous oxides are large amounts compared with the natural emissions such as those from forest fires. Amounts are increasing as the global consumption of fossil fu-els and the number of cars, trucks and SUVs increase. The geographic distribution of ni-trous oxide emissions reflects large power plants and population density in the northeast-ern United States and California. Nitrogen dioxide (NO2), the brownish-yellow gas in pol-luted air, causes respiratory distress and reacts with substances in the atmosphere to form toxic compounds. Purpose: Using methods of small -scale chemistry demonstrated by Dr. Steven Thompson of the Department of Chemistry of Colorado State University, noxious oxides of sulfur and nitro-gen will be generated and their contribution to acid rain will be observed. Materials: ( Per two students) Chemicals: Reagents needed in disposable Beral pipets.
0.5 M Potassium nitrite (KNO2) 2.0 M Sulfuric acid (H2SO4) 0.5 M Sodium sulfite (Na2SO3) Distilled water colored with 0.03% Bromcresol green 2.0 M NH3 (aq). Or Household Ammonia
Equipment: Two polystyrene Petri dishes with access port sealed with scotch tape, white grid paper Precautions/Hazards:
Goggles and aprons should be worn when using chemicals. Since trace amounts of SOx and NOx gases will be generated Petri dishes should be opened and closed only according to directions. Be sure to terminate the NOx and SOx gases, as directed with ammonia when finished. Care should be taken when using solutions of acids and am-monia.
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The Dynamic Duo
Acid Deposition Simulation
Procedure:
1. Prepare each Petri dish by heating the tip of a triangular file, glass rod or nail, or heat an old soldering iron. Use to melt a hole (access port) about 1 cm from the outside rim of the Petri dish. THIS MAY BE DONE BY THE TEACHER. Seal the port with scotch tape. Place two clean dry Petri dishes with sealed access ports on the grids. At the po-sitions indicated drop the following solutions:
Dish 1 (control) 1 drop 0.5 M KNO2
2 drops 0.5 M Na2SO3 2 drops distilled water with 1 drop acidity probe (0.03% bromcresol green sol)
Dish 2 1 drop 0.5 M KNO2 2 drops 0.5 M Na2SO3 2 drops distilled water with 1 drop acidity probe (bromcresol green)
Hazards: CAUTION: Wear goggles and aprons.
2. In dish 1 and dish 2 add drops of Na2SO3, KNO2 and bromcresol where indicated. 3. In dish 2 generate SOx and NOx by adding 2 drops of 2M H2SO4 first to Na2SO3 and
then to KNO2 by rotating hole in top of petri dish and removing tape and replacing tape first over Na2SO3, and then KNO2.
4. Observe the acidity probe. What color does bromcresol green turn in the presence of an acid? Compare with Control. What acids do you think were formed?
5. Stop the reaction by lifting the portal tape and adding 1 drops of ammonia.
KNO2 KNO2
Na2SO3Na2SO3
Bromcresol Bromcresol
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The Dynamic Duo
Acid Deposition Simulation
Disposal: Use a wash bottle to flood the system with water at the sink. Rinse Petri dish with distilled water and dry with paper towel. Long Term Project: You are a research scientist preparing studies of acid rain. In Petri dishes prepared like the ones above, design experiments using what you have learned from this lab and using chemicals from this lab to (1) compare the rates of transport of SO2 compared to NOx <Hint: use a succession of acidity probes radiating out from the source noxious gases to determine the rate of transport (how fast it moves). (2) Prepare a graph to show the aver-age of several experiments (3) Set up sinks, chemical barriers that might affect the move-ment. This could include sandy areas, grasslands, golf courses, styrofoam or different rock like limestone or quartz, lakes. Keep the area under the port in the Petri dish clear so you can add more acidity probes to monitor acidity over a period of time. Record your data and compare with other microenvironments to draw conclusions. Write a short ab-stract and summary for your project. Write a short hypothesis for each attempt and a con-clusion based on your experimentation. Include what areas are in most danger by acid deposition. Report on the Properties of Oxides (Enrichment) 1. Write the equations for the oxidization of sulfur dioxide to sulfur trioxide and for the
formation of the acid when the sulfur trioxide comes in contact with water. 2. From the results of the acidity probe after the addition of aqueous ammonia to the
above reaction, explain why aqueous ammonia can terminate the production of sulfu-ric acid.
3. Why does unpolluted rain have a pH of about 5.5? 4. Acid deposition is primarily caused by the oxidation of what substances? 5. Why is the atmosphere very sensitive to anthropogenic (man made as opposed to
natural) pollution? 6. Which gaseous air pollutants are the precursors to acid deposition? 7. What are natural buffers present in lakes that can neutralize acid deposition? 8. In North America acid deposition appears to be a more serious environmental prob-
lem in northeastern USA and northeastern Canada than elsewhere. What factors are responsible for this regional imbalance?
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The Dynamic Duo
Acid Deposition Simulation
9. How much nitrous oxide per km does a new car exhaust into the atmosphere Answers to Report on the Properties of Oxides:
1. 2 SO2 + O2 → 2 SO3 SO3 + H2O → H2SO4 2. Aqueous ammonia is basic. 3. Unpolluted rain is saturated with atmospheric carbon dioxide and thus has a pH of
5.6. 4. Oxidation of carbon, nitrogen, and sulfur causes acid reposition. 5. Anthropogenic pollution is of a much greater magnitude and is increasing. Also, the
atmosphere is more sensitive because it is a much smaller reservoir than the litho-sphere or hydrosphere.
6. Key atmospheric pollutants are sulfur and nitrous oxides. 7. Buffers in lakes are calcium and magnesium bicarbonate and organic acids entering
from the watershed. 8. Highest emissions of nitrous oxides occur in northeastern. US population density is
greater as is use of the automobile. 9. 1 gram nitrous oxide per km (kilometer) driven. References: Thompson, Steven (1989) Woodrow Wilson National Fellowship) Foundation Chemistry in the Environment, Princeton University, Princeton, New Jersey. Wagner, Maxine (1983) "Laboratory Manual for Chemistry" I ). 87-89. Cebco, Newton, Massachusetts.
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The Dynamic Duo
Electrolysis
Introduction: Some oxidation—reduction reactions do not occur spontaneously. They can be driven by electric energy. An electrolytic cell changes electrical energy into chemical energy by forcing a reaction to take place which would not take place otherwise. This process where an electric current is used to drive a chemical reaction is called electrolysis. The electro-lytic cell is made�up of a pair of electrodes, an electrolytic solution, a container and a bat-tery or power supply connected to the electrodes. In the electrolytic cell the reduction oc-curs at the negative electrode which is called the cathode. Oxidation occurs at the positive electrode which is called the anode. These reactions at the electrodes complete the elec-tric circuit and allows electric energy to be transferred from the battery to the electrolytic cell. During the electrolysis of H2O, the following reactions occur. 2 H2O (1) + 2 e- → H2 (g) + 2 OH- (aq) 2H2O (1) → O2 (g) + 4 H+ (aq) + 4 e- Materials: Battery, 0.1M Na2SO4 with Bromothymol Blue indicator to produce a green color, phenophthalein, 600 ml beaker or cut off 2 or 3 liter bottle with flat bottom, 2 small test tubes(75 x 100 mm), 9 V battery. Procedure: Fill the 600 ml beaker about 3/4 full with Na2SO4. Take 2 small test tubes and fill with solution in beaker allowing them to stay under solution. Set the wax coated 9 V battery on bottom of the beaker of Na2SO4 with bromothymol blue indicator. The solution should b green in color. Carefully move the test tubes into an upside down vertical position over battery terminals without losing liquid. Note which test tube is over which terminal. Allow some metal of each terminal to be exposed. As soon as you can see a difference in color and water level in test tubes, put a finger over the end of each tube and lift each out. Re-cord color of tubes and ratio of gas in tubes. Remove battery and rinse with water. Return Na2SO4 to the wand Na2SO4 container to be recycled. Questions: 1. Compare the volume of gas collected at the (+) electrode to the volume of gas col-
lected at the (-) electrode. 2. What color is the solution at (-) electrode? What does this indicate about the pH of the
solution is this test tube? Is this the anode or the cathode? 3. What color is the solution at (+) electrode? What does this indicate about the pH of the
solution in this test tube? Is this the anode or the cathode? 4. Write balanced equations for the two half reactions and the overall equation for the
electrolysis of water.
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Micro-Mixture Separation
Introduction: Nature provides us with elements and compounds; however, they are seldom found in their pure forms. Most often these substances are part of a mixture. The substances in a mixture are not chemically bound to each other — sort of like the parts to a puzzle —but are scrambled around like a handful of different coins. To make use of these substances it is necessary to separate them from each other. This separation process requires knowl-edge of the physical properties of these elements and compounds, such as density, solu-bility, melting point, and so on. This process requires knowledge of laboratory separation techniques, too. For example, to recover a dry solid, it is necessary to evaporate the liquid from the filtrate. In this experiment you will be asked to separate a micro-mixture of salt, sand, iron filings, sawdust, and benzoic acid (a white solid that is soluble in hot water, but relatively insolu-ble in cold water). No procedure will be given; it will be up to you to devise one. You are to design an experimental procedure that will separate the mixture, and recover all five components in their natural states (all are dry, granular solids). Materials: You will be given five small test tubes (four, empty and clean, the fifth, containing your mixture). All five must be returned empty and clean when you are finished. The compo-nents of the mixture should be retained in small cellophane baggies, taped closed, If there are any questions regarding the safety of any of your procedures, ask the instructor first. Procedure: 1. In this experiment, you are to provide the procedure. To obtain any laboratory equip-ment, see your instructor first. 2. Some suggested equipment: beaker, condiment cup, filter paper, evaporating dish, test tube, stirring rod, magnet, wax paper, heat source, funnel, Beral pipet, paper towel, dis-tilled water, apron, goggles and graduated cylinder Caution: For your own protection as well as your neighbor’s, before beginning the laboratory work, submit your procedure to the teacher for approval. Data: The following requirements will be asked of you for this experiment: 1. A statement indicating your objective. 2. A step-by-step outline of your procedure. 3. A flow chart showing the general outline of your procedure. 4. After the experiment, attached at the appropriate places on your flow chart will be
plastic bags containing the substance separated.
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Micro-Mixture Separation
5. Discussion of the sources of error in your separation and recovery techniques. Also indicate how you might do things differently to eliminate these errors.
Teachers’ Guide Materials (For Class Of 30): Mixture of the following ingredients: 8.0 g table salt 4.0 g sand 5.0 g iron filings 3.0 g sawdust 10.0 g benzoic acid. 12 x 75 mm culture tubes containing 1 gram of the above mixture (30) Empty 12 x 75 mm culture tubes (120) The following items should be available for student use: Filter paper Small funnels Distilled water Bunsen burners or hot plates Wax paper Magnet Beaker Condiment cup Evaporating dish Paper towel Apron, goggles Stirring rod Ice water Graduated cylinder Hints: 1. Writing up of the procedure and performing the actually laboratory work ought to take
place on different days. This will give the teacher time to properly check each proce-dure.
2. Do not be afraid to try this experiment. The ingenuity of the students can be amazing. They are excited and felt good when one of their separation techniques worked and they recovered one of the materials in their mixture.
3. A lab penalty could be assessed to those students who absolutely had to have a new set of materials.
Reference: Robert Becker, St. Louis, MO
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Making Strawberry Soda
Purpose: To observe the CO2 (g)/CO2 (ag) Equilibrium Suggested Topics For This Activity: Solubility of gases, equilibrium Background Information: Gases dissolve better in cold water. Gases dissolve better under pressure. Agitation makes them come out of solution. Carbon dioxide is very soluble in water. Lowering the temperature and increasing the pressure makes it more soluble. Analogy to carbonated drinks? CO2 (g) + H2O (l) ↔ CO2 (aq) + H2CO3 (aq) ↔ H+ (aq) + HCO3
- (aq) Precautions: Wear goggles and apron. Materials: 60 ml syringe lubricated with silicone lubricant and holes punched with hot nail or soldering gun at top of barrel on both sides opposite one another and holes punched in plunger at 20 ml and 40 ml, 250 ml plastic cup, tap wa-ter, Luer lock, red food coloring (bromcresol purple), baking soda, vinegar. Ice-salt-ice wa-ter bath, paper towel, overhead projector Procedure: 1. Generate 60 ml carbon dioxide in syringe using Chemistry of Gases method. 2. Push out 20 ml. Leave 40 ml of carbon dioxide in syringe. 3. Put about 25 ml deionized water into plastic cup. Add a few drops of red food color-
ing. ( Bromcresol Purple) 4. Take the syringe of carbon dioxide. 5. Remove Luer Lock. 6. Pull up 10 ml of colored water (Indicator Water) 7. Push plunger forward and place nail across barrel and through plunger. 8. Place in prepared ice-salt-water bath for fifteen minutes. 9. Remove from bath and wipe dry with paper towel. 10. Place across overhead turned on for a few minutes. Pull out plunger to increase vol-
ume. Place nail through top hole in plunger only.
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Making Strawberry Soda
11. Put back on overhead and observe. Questions: 1. What are you observing happening in the syringe when it is on the overhead? 2. Write the equation.
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The CO2 (g)/ CO2 (aq) Equilibrium
Equipment: 9-ounce (250 ml) plastic cup, special syringe with nail hole
Chemicals: 40 mL CO2 (g), ice water Instructions: Transfer 40 ml CO2 (g) into the special syringe. Pull 10 ml water into the syringe and install the syringe cap. Push the plunger inward until the nail can be inserted into the middle hole in the plunger as shown in the figure. Place the syringe into a large container of crushed ice and water. Allow the system to come to equilibrium over the next hour. Re-move from the ice and allow to warm to room temperature for 15 minutes. Next pull the plunger up to the 50 ml mark and insert the nail in the hole near the seal. Tap the syringe on the countertop. You will see bubbles of CO2 swirling out of solution. The equilibrium involves CO2 as the primary aqueous species. Approximately 1 CO2 in 600 exists as H2CO3 (aq): CO2 (g) + H2O (l) ↔ CO2 (aq) + H2CO3 (aq) ↔ H+ (aq) + HCO3
-(aq) Physical Properties of CO2: Sublimation point -78.5°C, colorless, odorless, sharp sensation to the nose when inhaled. Industrial Production: Carbon dioxide is manufactured by the combustion of hydrocarbons:
CH4 (g) + 2 O2 (g) → CO2(g) + 2 H2O (g) H = -803 kJ Industrial Uses: Refrigerant (accounting for over 50%), fire extinguishers, the soft drink industry, chemical reagent to make other compounds. Solubility of CO2: The solubility of CO2 (g) in water is 3.48 g per L at 0°C and 1.45 g/L at 25°C.
Instructions: The special purpose syringe is constructed by drilling two holes through the plunger, one is drilled in such a position that the syringe will
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The CO2 (g)/ CO2 (aq) Equilibrium
hold about 30 ml when the nail is flush with the rim of the barrel. Use a drill bit that is somewhat larger in diameter than the nail that is to be used. Drill the second hole in such a position as shown in the figure. The syringe will hold about 55 ml when the nail is flush with the rim of the barrel.
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Molar Mass of Butane
Purpose: To determine the molar mass, simplest formula and molecular formula of butane Suggested Topics For This Activity: Avogadro’s Hypothesis, Simplest & Molecular Formulas, Ideal Gas Law Background Information: Avogadro’s Hypothesis states that equal volumes of 2 gases at the same temperature and pressure contain equal numbers of molecules. For example: The molar mass of hydrogen is 2.0 g. If a sample of hydrogen gas has a mass of 4.00 g and a same volume of gas X has a mass of 60 g, then by a simple ratio we can find the molar mass of gas X. In this lab, the same idea is used where you will find the masses of 2 equal volumes of 2 different gases, air (molar mass = 28.9 g) and butane (molar mass to be found.) Using a syringe, one can measure the volume of a gas very accurately. In this lab we will use a can of bu-tane used to refill lighters as the source of butane. We used Ronson brand from Wal-Mart. You may have to ask for it. By measuring the temperature, the pressure of the butane and the mass of the butane, the Molar Mass of the Butane can be calculated using the Ideal Gas Law. PV = nRT. Precautions: Dispense and dispose of butane under hood. Wear goggles and apron. No open flames. Use the same syringe and Luer cap Materials: Refill can of butane, 60 ml syringe lubricated with silicone lubricant, analytical balance ac-curate at least to .01 of gram, piece of plastic or rubber tubing 1/8 ID 2 cm long icemaker tubing), thermometer, barometer Procedure: Find the mass of the empty syringe with Luer cap on.- Zero volume Using the same syringe, take the cap off and fill the syringe with 60 ml of air. Put on cap. Find the mass. Record. Empty the syringe of air. Working in the hood, fill the same syringe with 60ml butane by attaching the piece of tubing to the end of the butane can. Place the other end of the tub-ing on the tip of the syringe. Push down on the syringe until you have 60ml of butane in the syringe. Recap the syringe. Find the mass of the capped syringe which is filled with butane and record.
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Molar Mass of Butane
Take the barometric reading. Take the temperature of the air. Calculations: 1. From your data find the mass of air and the mass of butane. 2. If the molar mass of air is 28.9 g, find the molar mass of butane. 3. If butane is 82.8 % carbon and 17.2 % hydrogen, find the simplest formula of butane. 4. Find the molecular formula of butane. 5. Using the mass of the butane, the barometric reading, volume of butane and the tem-perature and the Ideal Gas Law, calculate the Molecular Mass of the butane. Use the Molar Mass calculated from atomic weights to determine the % error in the molar mass of butane calculated in calculation # 4 and Calculation # 5. Questions: 1. What are we assuming about the butane in the can? 2. Compare the Molar Mass of butane calculated by the two methods. Reference: Alan Slater, Chem Ed, 2001
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Composition of Hydrates
Introduction: Hydrates are ionic compounds (salts) that have a definite amount of water as part of their crystal structure. This water of hydration is released as water vapor when the hydrate Is heated. The remaining solid is known as the anhydrous salt. Many compounds contain water in specific molar proportions compared to the non�water part of the compound. The weight proportion of water in the compound is thus a constant for the compound. Copper (II) sulfate is one of these compounds. Usually, as in the case of hydrated copper (II) sul-fate, this water will be lost if the substance is gently heated. It is then possible to deter-mine the proportion of water present in the compound, by weight, and thus the number of water molecules per formula unit of the hydrated copper (II) sulfate. % H2O = (mass of water / mass of hydrate) X 100 The change from copper II sulfate hydrate to anhydrous salt is accompanied by a change In color. CuSO4·xH2O → CuSO4 + x H2O blue white Safety: Wear goggles and aprons. Soluble copper compounds are poisonous. Wash hands etc. if you get on body. Clean up spill with damp paper towel. Materials: Balance, ring stand, ring, bunsen burner, lighter, curved wire gauze, powered CuSO4, straw, dessicator ( you can make one out of coffee can), test tube holder, Beral Pipette, water Procedure: 1. Obtain 3 (10 x 75 mm) Pyrex test tubes. Make sure they are clean and dry. 2. Using a sharp pencil, mark the test tubes 1 through 3 on the white label surface. 3. Carefully weigh each test tube as precisely as you can and record the weights Imme-
diately In your data table. 4. Using the end of a clean straw, add a small pea size quantity of the hydrated copper
(II) sulfate to each test tube. 5. Weigh each test tube again and record the weight Immediately In the appropriate
space on the data table. The weight of the copper sulfate + the test tube should be between at least 0.2 grams more than the weight of the empty test tube but not more than 0.5 grams more than the weight of the empty test tube. If necessary add more copper sulfate or take out part of the copper sulfate using the straw and reweigh the test tube.
6. If you have spilled any of the compound on the balance or on the table top you must
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Composition of Hydrates
IMMEDIATELY clean It up with a damp paper towel. SOLUBLE COPPER COM-POUNDS ARE POISONOUS.
7. Set up a ring stand, a ring, a ceramic centered wire gauze and a Bunsen burner. Place the 3 test tubes, side by side, on the wire gauze so that they will not roll off.
8. Light the Bunsen burner and adjust it to get a hot flame. Place the burner under the wire gauze so that the tip of the flame is about one inch below the wire gauze
9. After heating for about 30 seconds, carefully grasp the base of the burner and move It back and forth under the five test tubes. This Is to prevent any one test tube from get-ting too hot. (If the compound Is heated too strongly, the water will be driven off and then the anhydrous compound will begin to decompose, giving off sulfur oxides, which are hazardous gases.)
10. When the color of the residue in each test tube has lost its blue color and appears to have a uniform grayish white, turn off the Bunsen burner.
11. Using a test tube holder, remove each test tube from the wire gauze and place imme-diately into a dessicator. (As the residue cools down, It will begin to absorb water from the humidity In the air. Placing the test tubes in the dessicator will prevent this.)
12. Allow the test tubes to remain in the dessicator for ten minutes to cool. The balance will not operate properly if the test tubes are still hot. During this time be sure that all weights have been entered in the computer.
13. Remove each test tube, in turn, from the dessicator and weigh it. Record each weight in the appropriate space in your data table and enter the weights in the computer.
14. After you have weighed each test tube, and when you are sure that it has cooled suffi-ciently to handle, stand one in your hand so that the bottom of the tube is cupped in your palm. Drop one or two drops of water from a pipette onto the solid and observe what happens.
15. Dispose of the chemical remaining In the test tubes In the container marked "used copper sulfate. Wash the test tubes and rinse them.
16. When the ring clamp and ceramic centered wire gauze have cooled, disassemble the heating apparatus and return each Item to Its appropriate location
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Composition of Hydrates
Report Page Data Table & Observations
What is the color of the copper(II) sulfate compound before It is heated and after It is heated ? Before After What happens when water is added to the anhydrous copper (II) sulfate? Analyzing Data And Drawing Conclusions: 1. Explain in words how to calculate the weight of the hydrate.
_______________________________________________________________________________________________________________________________________
2. Explain in words how to calculate the weight of the water lost. _______________________________________________________________________________________________________________________________________
3. Calculate the weight percent of water in each of the three samples in the experiment. Show work below and place answers in the chart above.
Test Tube Number 1 2 3
Mass test tube + hydrate
Mass of empty test tube
Mass of hydrate
Mass of test tube + anhydrous salt
Weight of water lost
% Water
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Composition of Hydrates
4. Calculate the average weight percent of water in the five samples. Show work. 5. Suppose one of the samples was not heated sufficiently to drive off all of the water.
How would the weight percent of water calculated for this sample from the lab data compare to the true value for the weight percent of water in hydrated copper (II) sul-fate ?
______________________________________________________________________________________________________________________________________________ 6. Explain how this lab illustrates the Law of Definite Proportions. ______________________________________________________________________________________________________________________________________________ 7. Explain what happened when water was added back to the anhydrous copper(II) sul-
fate in the test tube? ______________________________________________________________________________________________________________________________________________ 8. The true value for the percent of water of water in this hydrate is 36.0 %. Calculate
your % error. Show work. and place your answer In the blank below. ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Optional 9. Calculate the coefficient for the water of hydration, x, in the formula CuSO4 xH2O. Show all work.
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Composition of Hydrates
Teacher’s Guide Chemicals required ( per 30 students, each student working alone: 30-35 grams fine Copper II sulfate pentahydrate.) Equipment per student or lab group: 3 10X75 mm Pyrex test tubes – type you can write on 1 disposable drinking straw Pencil I ring stand I ring clamp 1 ceramic wire gauze Lighter or striker I desiccator (can make one using clean coffee can with 1 to 2 inches drying agent in the bottom). Cover the chemical with a round of screen wire with curved edges and put on lid. Soluble copper compounds should not be flushed down the drain unless municipal. Water system is designed to treat for such ions. (Lots of soluble copper compounds go into the system in an effort to clear tree roots from clogged pipes.) Expected results about 36 % water: X = 5 This laboratory was adapted by Eva Lou Apel and Barbara Schumann from a lab scaled down from a similar lab found in CHEMISTRY IN THE LAB by Masterson, Slowinski and Walford, 1987 and Woodrow Wilson National Fellowship Foundation Institute in Chemis-try.
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A Journey into the Atom: Isotopes
This activity will allow you to use your knowledge about the atom to discover the isotopes. Located at each lab station are 16 different zip lock bags. Without opening the bags (16 atom containers) you must count the subatomic particles and record all of the statis-tics. Then determine which isotope of an atom that you have. The subatomic particles are coded as follows: protons = garbonzo beans neutrons = white beans electrons = lentils
Questions: List all isotopes of the same element (set). _____________________________________ What do all of these isotopes have in common?__________________________________ What makes the various isotopes different from one another?_______________________ _______________________________________________________________________ Reference: Adapted from an activity written by Sara Spencer and Khysunja Frisella.
# of Protons # of Electrons # of Neutrons Atomic Number
Mass Number
Symbol Name
55
55
82
55
137
137 Cs
55
Cesium - 137
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Mole and Mass Relationships
Pre-Lab Discussion In a balanced chemical equations all reactants and products must be represented by sym-bols or formulas. The total number of atoms of each element must be the same on each side of the equation to satisfy the Law of Conservation of Mass. A calculation of the formula mass of a reactant or product enables us to convert from grams of a particular substance taking part in a reaction to moles of that substance. The mole relationship, given by the coefficients of tire balanced equation, then allows us to cal-culate how many moles of every other substance will take part in the reaction. In this experiment, we will investigate the quantitative relationships In reaction: NaHCO3(s)+HCI(aq) → NaCI(aq)+CO2(g)+H2O(g) A known mass of sodium hydrogen carbonate will be reacted with excess hydrochloric acid. Knowing the mass of NaHCO3(s) that reacts, we can determine from the balanced equation the mass of NaCl that should be produced. We compare this theoretical value with the actual experimental mass of NaCl produced. This experiment should aid In the understanding of the mole-mass relationships that exist in a chemical reaction and in the Interpretation of a balanced chemical equation. Purpose Compare the experimental mass of a product of a chemical reaction with the mass pre-dicted for that product by calculation. Safety Wear goggles and aprons. Beware of HCl Materials Evaporating dish, sodium hydrogen carbonate, 6M HCl, spoon, Beral Pipette for acid, bal-ance, ring stand, ring, wire gauze, Bunsen burner, lighter, tongs or damp paper towel, wa-ter bottle distilled water Procedure 1. Find the mass of the evaporating dish. This is mass (a) In your data table. Be sure to record the proper number of significant figures. 3. Add between 1/3 and 1/2 spoon of sodium hydrogen carbonate (NaHCO3) to evaporating dish. Record this mass as (b) in your data table.
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Mole and Mass Relationships
4. Using a Beral pipette, slowly add 6MHCI to the NaHCO3 in the evaporating dish, a few drops at a time. CAUTION: Handle this acid carefully, It can cause painful burns if it touches your skin. Continue adding acid until the reaction (bubbling) stops. Carefully tilt the evaporating dish back and forth a couple of times to make sure that the acid has contacted all the NaHC03 5. Set up the ring stand, ring, and wire gauze. Place the dish on the wire gauze. 6. Holding the burner in your hand, gently heat -the evaporating dish. Use a low flame- and move the burner back and forth to avoid spattering. When almostt all the liquid Is gone, heat gently by moving the burner back and forth until no liquid remains. Allow the dish to cool for 10 minutes. 7. Find the combined mass of the evaporating dish and its contents (NaC]). Record this mass (c) in your data table. 8. Rinse the evaporating dish. Wash It with detergent and water, rinse with tap water and then with distilled water. Then flame dry the clean evaporating dish by putting on wire gauze and heating it in the hot part of a burner flame for about 5 minutes. Leave for next group.
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Mole and Mass Relationships
Report Page
Calculations: Show All Work 1. Find the mass of the NaHCO3 reactant. (b-a) ______________________g 2. Find the mass of the NaCl product. (c-a) ______________________g 3. Find the moles of NaHCO3 reactant. __________________moles 4. Find the moles of NaCl product __________________moles Conclusions And Questions 1. According to the balanced equation for the reaction used in this experiment, what is the ratio of moles of NaHCO3 reacted to moles of NaCl produced? 2. What is the ratio of moles NaHCO3 actually reacted to moles of NaCl actually produced in your experiment? (Use the information on moles produced from calculations 3 and 4 above. Divide numbers of moles. Do not leave as 2 decimal fractions.) 3. Using the balanced equation, calculate the mass of NaCl you would expect to get when the amount of NaHCO3 you used in the lab are reacted with HCI. 4. Compare the amount of NaCl actually produced In your experiment with the amount
Measurement Weight (g)
(a) weight of evaporating dish
(b) weight of evaporating dish + NaHCO3
(c) weight of evaporating dish + NaCl
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Mole and Mass Relationships
expected by, calculating the percent error. Assume the expected amount calculated In the previous question to be the accepted value. Show work. 5. If the masses of all but one of the substances that take part in a chemical reaction are known, explain why it is possible to determine the unknown mass by subtraction. 6. In the chemical reaction CaCO3 → CaO + CO2, if 40.00 g of CaCO3 are decomposed: (show work) (a) How many grams of CaO are produced ________________g (b) How many grams of CO2 are produced? _________________g 7. In the reaction N2 + 3 H2 → 2 NH3, if 20.00 grams of hydrogen react: (Show work) (a) How many grams of ammonia are produced? _________________ g (b) How many grams of nitrogen react? _________________g
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Relative Strengths Of Acids And Bases
Purpose: To use indicators to determine the approximate pH and to develop a table of the comparative strengths of a series of acids and bases and their conjugates. Introduction: All strong acids have approximately the same acid strength in water solution since they are highly ionized. Their ionization reaction with water is almost 100/% even in fairly con-centrated solutions. Strong bases behave the same way. In aqueous solutions of weak acids, the concentration of the hydronium ion is quite low even in dilute solutions. In aque-ous solutions of weak bases, the hydroxide ion concentration is also very low. Since all of the solutions to be used are the same concentration, the varying pH values (which are H3O+) can be used to estimate the relative % ionization or the strength of the acids and bases. Materials: Spot plate; distilled water; 0.1 M solutions of hydrochloric acid, sodium hydroxide, oxalic acid, boric acid, ammonium hydroxide, acetic acid, sodium bicarbonate, nitric acid, sodium hydrogen sulfate, sodium phosphate; saturated solutions of H2S and CO2; indicators: bromthymol blue, methyl orange, phenolphthalein, alizarin yellow, bromcresol purple, cys-tal violet. Procedure: Part 1: Add about 5-6 drops of one of the solutions to 6 spots on the spot plate. Add only 1 micro drop of each indicator using Beral pipette to the separate spots. Record the color that each indicator produces on the correct line of the data table. Repeat this procedure with each of the solutions. When cleaning the spot plate between uses, be sure to rinse it thoroughly and use distilled water for the final rinse. BE VERY CAREFUL TO RETURN ALL DROPPERS TO THE CORRECT BOTTLE OR BEAKER. Make sure the spot plate is clean. Rinse with deionized water.
View against a white background.
Indicator Color Transition pH
Acid Transition Alkaline
Crystal Violet Yellow Blue Green Blue 0.8 – 1.1
Methyl Orange Pink Orange Yellow 3.2 – 4.4
Bromcresol Purple Yellow Clear Blue 6.0 – 7.6
Bromthymol Blue Yellow Green Blue 6.0 – 10.0
Phenolphthalein Colorless Pink (pale) Red (hot pink) 8.2 – 10.0
Alzarin Yellow Yellow Orange Red (blue above a pH of 12)
10.5 – 11.4
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Relative Strengths Of Acids And Bases
Table of Indicator Colors Report Page Conclusion Questions: 1. As the strength of an acid or base decreases, the strength of its conjugate
____________________________________________________________________ 2. Using the information that the solutions are 0.1 M, what should the pH of the acids be?
________________ Of the bases? _______________ 3. How does the pH of the strong acids and bases compare with the pH calculated from
the information that the solutions are 0.1 M? ________________________________ ____________________________________________________________________
4. How does the pH of the weak acids and bases compare with the pH calculated from
0.1 M Solution
Crystal Violet
0.8—1.1
Methyl Or-ange
3.2—4.4
Bromcresol Purple
6.0—6.8
Bromthy-mol Blue 6.0—7.6
Phenopthal-ein
8.2—10
Alzarin Yel-low
10.5—11.4
Approxi-mate pH
HCl
NaOH
H2C2O4
H3BO3
NH4OH
HC2H3O2
H2CO3
H2S
NaHCO3
NaHSO4
HNO3
Distilled H2O
Na3PO4
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How Do You Know A Chemical Reaction Is Happening? Purpose: To make accurate observations of reactions and to discover evidences of chemical reac-tions. Materials: Cassette with set of chemicals “A”, “B”, “C”, “D” in plastic pipets and solid “E” , 24 well re-action plate or a 96 well reaction plate Procedure: 1. Record the number of your cassette in the proper place on your report page. 2. In your reaction plate, mix all possible combinations of chemicals “A”, “B”, “C”, “D”
and “E” using 6 drops of each solution if using a 24 well plate and a small piece of solid. (If using a 96 well plate, use 3 drops of each solution and a small piece of solid.)
3. Make careful observations for all reactions and record the observations in ink in the
following data table. 4. When you have completed the experiment, dump the contents of your reaction plate in
the waste container specified by your teacher and clean your reaction plate. Rinse it with distilled water. Return all chemicals to the cassette.
5. Compare and discuss your results with other student groups.
Data Table Cassette # ________
Solution A B C D
E
D
C
B
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How Do You Know A Chemical Reaction Is Happening? Report Page: i. List at least 3 evidences of a chemical reaction.
(1 )
(2 )
(3 ) 2. What is the difference between a clear and colorless solution? 3. What is a precipitate? 4. How would you distinguish between an observation and an interpretation? 5. How did your results compare with other groups? Explain. 6. List procedures and techniques that a good laboratory chemist should follow. 7. If you had the opportunity to do this lab again, what would you do differently? 8. What are the 3 most important things you learned from this lab?
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How Do You Know A Chemical Reaction Is Happening? Teacher’s Notes Materials: The following should provide stock solutions for 5 classes. Use distilled H20 for all solu-tions. 3 M HCI-—------------------—Add 63 ml concentrated HCl to 187 ml distilled water bromcresol green solution—- Add 0.05 gram of brorncresol green powder to 13 ml of 0.01
NaOH. Add drops of this solution to 125 ml water until the color matches that of the CuSO4 solution.
0.1 M CuSO4 solution----- Add enough water to 3.1 g of CuSO4
.5H20 to make 125 ml. of solution.
0.10 M KI solution----------Add enough water to 4.25 g of KI to make 250 ml solution. This
solution needs to be made fresh each year. 3 M NH4OH------------------ Add 25 ml NH4OH to 100 ml of water.
0.1 M AgNO3 -------------------- Add enough water to 2.9 g AgNO3 to make 125 ml. of solution.
Be sure to check the HCI solution to see if the color change occurs with the copper sulfate solution. If not add more acid to the stock solution. Label the cassettes. It Is suggested that different types of cassettes be used for the odd and even sets. Cut Beral pipettes to fit in cassette. Label odd numbered sets with one color permanent marker and the even numbered sets with a different color permanent marker and place tape over label to protect it. Fill pipettes and place In cassette. Labeled small bottles are convenient to use to fill the pipettes with the solutions. Containers for the zinc can be made from the cut off bulbs of 2 pipettes. Odd Numbered Sets Even Numbered Sets A hydrochloric acid (HCl) A hydrochloric acid (HCl) B Copper (II) sulfate solution B bromcresol green solution C potassium Iodide solution C potassium Iodide solution D ammonium hydroxide D silver nitrate solution E mossy zinc E mossy zinc Suggestions: 1. Hand out odd and even numbered sets alternate lab stations. 2. Although the 2 sets are not identical, they will LOOK Identical. DO NOT call attention to the differences between the two sets. Let the students assume they are all the same.
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How Do You Know A Chemical Reaction Is Happening? 3. If students should run out of test chemicals, the teacher should refill the pipets. Hazards: Wear goggles & aprons. Students should be warned to avoid getting the solutions on their hands or clothing. Skin irritation and/or stains could result. References: Marian Hart, How Do You Know A Chemical Reaction Is Happening’, Microscale Chemis-try, The Woodrow Wilson National Fellowship Foundation Chemistry Institute 1987 Cur-riculum Module. Interdisciplinary Approaches To Chemistry, Reactions and Reason Module, Harper & Row. ‘Blazing Test Tube Lab Manual’, Jean Dean, Bartlesville High School Results:
Odd Numbered Solutions
Solution A B C D
E
Bubbles on metal
Black, brown coating
No change No change
D
“Smoke” odor, warm
Clear, deep blue
No change
C
No change Yellow, brown precipitate
B
Clear, green solution
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How Do You Know A Chemical Reaction Is Happening?
Even Numbered Solutions
Solution A B C D
E
Bubbles on metal
No change No change Black
D
White precipi-tate
No change Pale yellow pre-cipitate
C
No change No change
B
Clear, yellow solution
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Qualitative Polymer Lab
Introduction: Recycling has become an important part of our lives. We have recycled paper and glass. Now more and more we can recycle plastic. There are many types of plastic. The plastics industry has voluntarily coded plastic so that it can be recycled. The ways that plastic has been coded is listed below. This lab will point out the differences in some of the most ~ types of plastics, why they can be separated, and why not all plastics can be recycled in the same manner. Materials: 6 density solutions Tongs Tweezers Bunsen burner Acetone Copper wire Striker Boiling water Hole punch Tap water Six samples of different polymers Distilled water Paper towels Procedure: Part 1: Physical Characteristics 1. Check for transparency (Is surface a glossy or matte finish?) 2. How easily does the sample bend? Does it have fine lines called "crazing after it is
bent? 3. If possible pull the sample in two directions. How easily does it stretch? Part 2: Density When changing from one density solution to another, rinse with distilled water. Then pat dry with paper towel. 1. Drop the sample into water. Be sure air bubbles are not trapped underneath.
• If it floats in water, check the density in the alcohol solution of density 0.940 g/cm3
• If it floats in this solution, place it in alcohol solution with density 0.925 g/cm3 2. If it sinks in water, check its density in saturated salt water solution of density 1.20 g/
cm3 • If it sinks in this solution, place it in corn syrup of density 1.40 g/cm3 to identify
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Qualitative Polymer Lab
it. • If it floats in the saturated salt water, place it in the 10% salt solution of density
1.07 g/cm3 3. Determine the density range of your sample. Part 3: Copper Wire Flame Test - Do Under the Hood over Aluminum Foil 1. Using the tongs, hold a piece of copper wire in the flame of a Bunsen burner until red
hot. Remove from the flame and carefully push the hot wire through the sample. 2. Place the wire back in the flame. Observe the color of the flame that comes from the
wire. Note: the halogens (fluorine, chlorine, bromine and iodine) will react with copper to create copper (II) ions which will give off a green flame. The absence of copper (II) ions will result in a yellow flame. Use the polymer names to explain the color of the flame and narrow your polymer choice.
Part 4: Combustion Test - Do under the Hood over Aluminum Foil 1. Use a hole punch to punch out a circular piece of the sample. 2. Using the tongs, hold the piece in the flame of the Bunsen burner until it begins to
burn. Remove the samples from the flame and note the color the flame produces as it continues to burn.
3. When the reaction has finished, quench the sample in the beaker of tap water. LDEP (4) burns slowly allowing excess of enough oxygen to give a hot, blue flame. PP (5) burns quickly, resulting in incomplete combustion, and a cooler yellow flame.
Part 5: Heat Test 1. Using tongs, plunge the sample into boiling water. PET (1) will show some reaction. The others will not. Part 6: Acetone Test 1. Place the sample in acetone for about 5 seconds. Remove and press between fingers. 2. The polymer chains from styrene will “1oosen up” in acetone. The surface will become
soft. The other chains will not. Teachers' Information: 1. Use small pieces of plastic about 2 cm by 2 cm. Have knowns numbered. 2. Try to get unknowns of same code from different containers. Do not use PVC as an
unknown. 3. Follow directions for using hood and doing over aluminum foil. PVC contains chlorine
which reacts with the copper to give the green flame. 4. Use the Coding Chart used for recycling plastics. Baby food jars can be used for den-
sity solutions.
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Qualitative Polymer Lab
Density:
Type:
PP is insoluble in acetone and is stronger than high or low density polyethylene. It is used is aerosol caps. PET is transparent and tough making is good for beverage containers. Polyethylene is translucent and not brittle. It is chemically resistant
Density Solutions
Proportions
g/cm3 0.87 4 parts ethyl alcohol to 1 part water 0.925 10 part ethyl alcohol to 7 parts water 0.94 1 part ethyl alcohol to 1 part water or
3 part isopropyl alcohol to 1 part water 1.00 distilled water 1.07 10% NaCl - water 1.20 saturated NaCl solution 1.40 White Karo Syrup
Type Density poly-4 methyl-1 pentene 0.83 polypropylene 0.90 – 0.91 low density polyethylene 0.92 – 0/94 high density polyethylene 0.95 – 0/97 polystyrene 1.04 – 1.07 polyvinyl chloride 1.30 – 1.34 polyethylene terephthalate 1.38 – 1.39 polytetrafluoroethylene 2.2
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Qualitative Polymer Lab
Physical Characteris-tics
Density Range (S or F)
Copper Wire
Acetone Heat Combustion
1 0.87 1.00
0.925 1.07
0.94 1.20
1.40
2 0.87 1.00
0.925 1.07
0.94 1.20
1.40
3 0.87 1.00
0.925 1.07
0.94 1.20
1.40
4 0.87 1.00
0.925 1.07
0.94 1.20
1.40
5 0.87 1.00
0.925 1.07
0.94 1.20
1.40
6 0.87 1.00
0.925 1.07
0.94 1.20
1.40
Unknown 0.87 1.00
0.925 1.07
0.94 1.20
1.40
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Qualitative Polymer Lab
Discussion: Letter of Unknown _____________ Type __________________ Questions: 1. Your boat is sinking and you are not a good swimmer. You notice 6 solid plastic blocks
labeled 1-6. Having only two arms, which ones should you grab and why? ________________________________________________________________________________________________________________________________________
2. You wish to make a handle for a cooking pan out of plastic. Which type would you use and why? ________________________________________________________________________________________________________________________________________
3. If a person wishes to transfer fingernail polish to a plastic container, which type should they avoid and why? ________________________________________________________________________________________________________________________________________
4. Why wouldn't polystyrene be good for 2 liter soda bottles? ________________________________________________________________________________________________________________________________________
5. If plastics were all mixed together, what would be a good way to separate them? ________________________________________________________________________________________________________________________________________
Reference: Adapted from two labs published in Chem 13 News In 1994. These labs contained Infor-mation from an NSTA publication: Polymer Chemistry.
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Qualitative Polymer Lab
Recy-cling Code
Type of Plastic
Characteristics Density (g /cm3)
Type of Use
1 Polystyrene teraphthalate (PET)
Transparent, flexible but crazes; rigid, tough; does not break when hit with a ham-mer, usually glossy, drips when burning and produces little smoke
1.38—1.39 Clear 2 L beverage bottles
2 High density polyethylene (HDPE)
Stiff, but will bend; opaque, rough surface, drips when burning, forms white smoke and smells like candle wax, insoluble in acetone
0.95—0.97 Milk jugs, bleach bottles, water bot-tles
3 Polyvinyl chloride (PVC)
Rigid, or flexible if plasticiz-ers are add, very glossy, burns with a yellow flame; may have green spurts and HCl smell; gives copper wire test—green flash; difficult to ignite and extinguishes when flame is removed; soluble in toluene, not acetone
1.30—1.34 Saran wrap, Tygon tubing, plastic drain pipe, shower cur-tains, vinyl car tops, some water bottles
4 Low density polyethylene (LDPE)
Opaque, very flexible, burns with drips, white smoke: in-soluble in acetone
0.92—0.94 Plastic bags, gar-ment bags, coffee can lids
5 Polypropyl-ene (P/P)
Translucent to opaque; smooth surfaces have luster but usually low gloss, burns with drips and blue flame with yellow tips, produces white smoke; acrid order; insoluble in acetone
0.90—0.91 Aerosol can tops, rigid bottle caps, candy wrappers, bottoms of bottles
6 Polystyrene (PS)
Transparent to opaque; glossy, brittle to semi rigid, burns with yellow flame and no drips; gives off clouds of dense black smoke and clumps of carbon in the air; softens and bubbles but does not drip flaming drips, very soluble in acetone
1.04—1.07 Hard clear plastic cups, foam cups, eating utensils, deli food containers
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Acid Rain Project
Purpose: To measure the pH of local rainwater over a period of time and present results. Background: It is important to keep track of the pH of local rain because of the environmental problems caused by acid deposition. Although it might seem a simple task, the accurate measure-ment of the pH of rain is not easy. Water dissolves carbon dioxide from the air and addi-tion or the loss of this gas can produce sizable changes in the pH of the sample. For best results, the rainwater should be tested soon after its collection. Acid indicators will work for this application since they can be transported to field sites or used at home. Description: Each group will consist of three people in the same class. They will design a collector for acid rain and collect rain and test with pH meter or com-parison to indicators for a minimum of 5 times. The results will be displayed in the form of a graph. At the end of the project the collector or a picture of the collector must be turned in along with a description of where the collector was located and why. All member. of the same group will receive the same grade. All of the report will be displayed on a large poster board. Tips: 1. A zip-lock bag should be a part of the collector design. The rain samples should be
collected soon after the rainfall. Squeeze excess air out of bag and seal. Refrigerate. Bring to school the next day to test before school.
2. Do not collect acid rain when there is a threat of lightning.
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Acid Rain Project
Report Page (This project counts as two lab grades. All persons in the same group get the same grade.) Early Due Date _________ Regular Due Date __________ Name _________________________________________________________________ Name __________________________________________________________________ Name _________________________________________________________________ This report should be presented on a large poster board with this page attached. It will be graded as follows: 1. A photograph or photographs of your rain collector and the surroundings and reason
for location. (20pt.) 2. Data Table of at least five samples.(20pt.) 3. Graphing of Data (10pt) 4. Computer Graphing of Data ( 10 pt.) 5. Explanation of how acid rain is formed. Include three different acid rain causing com-
pounds. You must show equations. (15 pt.) 6. Explanation of destruction caused by acid rain. (15 pt.) 7. Appearance of Report. Is it easy to understand and neat? (10 pt.) Bonus 5 points 1. Exchange of data with another school. 2. Early due date
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Half-Life Simulation
Background: The rate of decay of radioisotopes is measured in half-lives. One half-life is the time it takes for one half-life of atoms in a sample of radioactive material to decay. In this experi-ment you will use pennies to simulate the relationship between the passage of time and the number of radioactive nuclei that will decay. As with real nuclei the passage of times will be measured in half-lives. Suppose that the Lincoln side of the penny represents a radioactive isotope of the element pennium called Lincolnium. The product of this isotope's decay is the back side called backonium. You will place 160 pennies in a pizza box with the Lincoln side up. This means that it all starts out radioactive. Every time you shake the box side to side a half-life has passed. All of the pennies that are not Lincoln side up will be removed. They have decayed. The box will be shaken again simulating another half-life. After you have completed six half-lives of decay, you will share your data with the class. The data will be graphed. The curve that you construct applies to the decay of every radio-active isotope. The only difference is that the half-life is a different time period for each isotope. A half-life can be a very long period measured in years or a very short period measured in minutes. Your curve will also show the rate of decay expressed n6' only in numbers of nuclei, but in masses. Objective: To simulate the radioactive decay of radioactive nuclei by using pennies. Materials: 160 pennies, a pizza box, graph paper, pencil, paper towels Procedure: 1. Place the 160 pennies in pizza box with Lincoln sides up. 2. Start out with zero decayed and 160 radioactive when you record. 3. Close the container and shake gently from side to side. 4. Open the container and remove the pennies which do not have the Lincoln side up. 5. Record the number of decayed as back side up and the radioactive as Lincoln side up. 6. Repeat steps 3-5 five more times. At this point you will have 6 half-lives. 7. You should have seven numbers in your final column, representing atoms remaining 8. after zero, one, two, three, four, five and six half-lives. 9. Pool your data by finding total number of atoms decayed for total class after each half-
life. 10. Each group is to record data on overhead.
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Half-Life Simulation
11. Prepare a graph by plotting the number of half-lives on the X-axis and the number of un-decayed atoms remaining for each half life on the Y-axis.
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Half-Life Simulation
Data Table 1:
Data Table 2:
Half Lives Un-decayed (marked) Decayed (marked)
Start 160 0
1
2
3
4
5
6
Half Lives
Lab Pair 1 2 3 4 5 6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Total
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Colligative Properties
Purpose: To study on of the colligative properties, ie, freezing point, of a salt water solution Materials: rock salt (NaCl), crushed ice, custard (6 cup milk, 1 cup sugar, 1 tablespoon vanilla), plas-tic bucket, small plastic cup, plastic spoon, thermometer, balance Introduction: Colligative properties are those properties of solutions which are determined by the num-ber of particles in solution. Freezing point and boiling point are examples of colligative properties. The addition of a nonvolatile solute affects the freezing point and boiling point of a solution by lowering the vapor pressure of the solvent. Vapor pressure depends on the number of surface particles which attain enough kinetic energy to escape the liquid state. Since the presence of solute particles decreases the number of solvent particles on the surface, fewer particles attain the energy to escape, and thus the vapor pressure is lowered. The boiling point and the freezing point are both functions of the vapor pressure and conse-quently are affected by this change in vapor pressure. For water, it has been found experi-mentally that one mole of nonvolatile solute particles will raise the boiling point of 1000 9 by 0.512 degrees Celsius and lower the freezing point by 1.86 degrees Celsius. One mole of solute dissolved in 1000 g of solvent is called a one molal solution. Since ionic solutes dissociate in solution, a one molal solution of these solutes provides two or three times the number particles per mole and this the boiling point elevation and the freezing point depression is doubled or tripled accordingly. This is true only of dilute solutions due to the re-association of particles when their concentration increases. In this experiment we will investigate the affect of rock salt (NaCl) on the freezing point of water. Since our solution will not be dilute, the experimental freezing point will deviate con-siderably from the theoretical freezing point. Explanation: Adding salt to water lowers the temperature at which it will freeze. A saturated salt water solution will freeze at about -20 degrees Celsius. The salt interferes with the crystalline structure of ice. When .you put ice cream batter in the cup or in a freezer in contact with the ice-salt solution, heat flows from the warm batter to the solution. The heat will go to melt the ice before it raises the temperature of the ice-salt solution. If enough heat is lost by the batter, it will freeze at about 0 degrees Celsius.
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Colligative Properties
Procedure: 1. Add ice to bucket to about 2/3’s full 2. Add about 1/3 cup of salt to bucket. 3. Stir ice, salt mixture with metal spoon until slushy. 4. Get plastic cup of custard from teacher. 5. Immerse it as far as possible into the slush. Be careful not to get any of the salt mix-
ture into the plastic cup. 6. Stir until frozen being careful not to get salt mixture into plastic cup. 7. It will not be frozen as hard as commercial ice cream. 8. Record temperature of ice, salt slush when ice cream is frozen. 9. Enjoy. Reference: Janet Carpenter, Teacher, San Antonio
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Colligative Properties
Data Table: 1. Mass of plastic bucket. __________g
2. Mass of ice and bucket. __________g
3. Mass of bucket, salt and ice. __________g
4. Mass of salt (NaCl) __________g
5. Mass of ice (H20) __________g
6. Moles of salt used. __________
7. Molarity of solution __________
8. Expected freezing point (theoretical). __________
9. Experimental freezing point. __________
Calculations: Label by line number Conclusions: Show Calculations 1. What is the freezing point of a 1m solution of sugar (C12H22O11) + water? 2. What is the freezing point of a 1m solution of NaCl solution in water?
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Micro-Titration Apparatus
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Top Secret !!! For Your Eyes Only
Because of your expertise in such matters, you have been selected for a top secret mis-sion. That mission, should you choose to accept it, is to work with the “photographs” of suspicious characters contained in the envelope or zip-lock bag. They are members of a family of secret agents, but the most deadly has not been photo-graphed. Your jog is to arrange the photopgrpahs until you can draw the missing agent. Clue One – There are many ways to begin the arrangement. You could try grouping the “people” using ways in which they are alike. Or, you might find this gets you where you want to go the fastest. Or, you might begin sequencing the pictures. Here’s an example. If you were given 100 slips of paper with the numbers 0 to 99 written on them, you could put them in a long row by sequencing them. That is, each number would be one more than the last. Once you had them in a long row, you could then break the sequence to create columns without changing the original order. Your new arrangement would look like this. Across Horizontally – Row Down Vertically - Column 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 36 37 38 39 Notice that each row has something in common. The first row has all the single digit num-bers. The other rows all begin with the same number. Also, notice that each column has something in common. They all end in the same number. If one of the numbers is miss-ing, you can easily figure out which one it is by looking at the row and column it is in. The missing number must begin with a 3 and end with a 5. This is the idea of what you must do with the “secret agents”. But how cah you sequence things that are not numbers? Notice that you can identify certain properties or characteris-tics on each picture. They have hair, button or body designs, fingers, arms, facial expres-sion and bodies. The second clue is that each “secret” agent is different from every other one in two of those properties. In other words, no tow pictures have exactly the same of these properties. If you find either one of those two, you can sequence the pictures because the properties change in some regular way. When you are finished you should have three rows. The rows do not necessarily have the same number of pieces as they do in the example above. Remember, the goal is that all members of a row have something in common and all members of a column have some-thing in common. That will let you identify the “missing agent”. When you have finished the final arrangement, answer the following questions on another sheet of paper. Put your set number on your paper. 1. In what TWO ways are all the secret agents different? 2. Once organized, what do the agents in each ROW have in common?
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Top Secret !!! For Your Eyes Only
3. What do the agents in each COLUMN have in common? Draw the missing agent. (If you do not accomplish this task in 30 minutes, this envelope will self-destruct, taking you with it. (Well, maybe not.) Good luck. If you get stuck, the Agency will disavow any knowledge of your actions. However, you may be able a little (very little) from you teacher. Go for it. TEACHER: Cut apart one page of the figures. Put into envelopes or zip-lock bag. Number envelopes or bags. Remove one figure from each set. Keep track of which one you remove from each set. Credit: I do not remember where I got this. I think it is from the Frontiers in Science Program from a lady who taught at a private school in Dallas.
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Top Secret !!! For Your Eyes Only
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Lab Check List
1. Comes prepared for lab ________________________________________________________________________________________________________________________________________
2. Follows directions ________________________________________________________________________________________________________________________________________
3. Stays on task ________________________________________________________________________________________________________________________________________
4. Maintains appropriate noise level ________________________________________________________________________________________________________________________________________
5. Cleans up & returns materials ________________________________________________________________________________________________________________________________________
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Chemistry Pledge & Songs
Chemistry Pledge I pledge allegiance to the periodic table And to the theory for which it stands One theory, under Moseley, With symbols and numbers for all. Goggle Songs (Sung to the tune of "Pop Goes the Weasel" ) Wear you goggles everyday For if you don't, you'll regret the day Treat you eyes with the greatest of care For if you don't, they won't be there You'll be blind for the rest of your life, Nothing you will see. When they ask you what you did, You'll say "IN CHEMISTRY!" (Sung to the tune of "I'm a Little Teapot") I'm a little chemist, short and stout (Point TO goggles) Here are my goggles (Point to eyes) Here are my eyes (Hands on hips) When I don't wear Goggles, My Teacher Shouts! (Cup hands to mouth & wag finger) Just put them on or just get out!
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Safety Test Lab Practical
Visit the marked lab station for your test version. Write in your own words the rule that is illustrated.
Station Safety Rule
47
48
49
50
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Putting Polyvinyl Alcohol Into Solution
1. Never try to make more than one liter at a time. 2. Measure out 40 g of polyvinyl alcohol. 3. Place 1 liter of deionized water into 4 cup Pyrex measuring cup. 4. Sprinkle alcohol over top and beat with wire beater for about 30 seconds. 5. Microwave for 2 minutes on high. 6. Remove from oven and beat with wire beater 30 seconds. 7. Heat again for 4 minutes on high in microwave. 8. Remove and beat again for 30 seconds. 9. Heat again for 4 minutes on high in microwave. 10. Remove and beat for 30 seconds. 11. Cool. You may have a thin film on top.
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Relative Strengths of Acids and Bases
Student Baskets: 1 96-well spotplate Water bottle with distilled water Large baskets on Lab Table – one per two lab groups: 0.1M HCl (Hydrochloric Acid) 8.25 ml / liter using Muriatic Acid 0.1M NaOH (Sodium Hydroxide) 4.2g/liter 0.1M Oxalic Acid H2C2O4) 9g/liter 0.1 Boric Acid (H3BO4) 6.2 g/liter 0.1M NH4OH (Ammonium Hydroxide) 6.75 g/liter 0.1M HC2H3O2 (Acetic Acid) 5.75g/liter 0.1M NaHCO3 ( Sodium Bicarbonate) 8.41 g/liter 0.1M HNO3 (Nitric Acid) 6.35 ml/liter 0.1M NaHSO4 (Sodium Hydrogen Sulfate) 13.8 g/liter 0.1M H3PO4 (Phosphoric Aid) 7ml/liter Saturated H2S solution: Sodium Sulfide + 6M HCl in glass collecting Bottle through distilled water. Saturated H2CO3 (Carbonic Acid) Solution: CaCO3 + 6M HCl in glass collecting bottle bubbled through distilled water. Small Basket on Table – one per two lab groups: Dropper bottles or Beral Pipettes of Indicators in Set Bromthymol Blue Methyl Orange Phenolthalein Crystal violet Alzarin Yellow Bromcresol Purple Small cup of Q-Tips
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Money Saving Tips To Teach Quality Chemis-try At Bargain Basement Prices
Become a smart shopper. Learn which stores in your area have the best prices.
Find out which stores in your area accept purchase orders. Ask to be able to use these for science purchases. If you find a good price on a needed item, check with the store management to see if they will accept P.O.‘s. Also, check to see if you can get reim-bursed for cash purchases of items at super discount stores such as Sam’s Clubs or Dol-lar Stores.
Microscale your labs. It is much cheaper in addition to being safer.
Substitute free and recycled materials as well as consumer chemicals for traditional lab materials. Students appreciate the use of recycled materials.
Use muriatic acid (approximately 8 M hydrochloric acid) instead of reagent grade hydro-chloric acid in all labs except for high level quantitative work and procedures which need 12 M HCl. Muriatic acid can be purchased at grocery stores, discount stores or pool sup-ply stores.
Use baby food jars to dispense and store non corrosive dry chemicals for labs. These can also be used in place of 60 ml beakers when Pyrex is not needed for heating purposes.
Use 10-12 oz throw away glass soft drink bottles (when you can find them) instead of re-agent bottles.
Use soup cans for hot water baths and cut off 2 liter soft drink bottles for ice baths.
Be very careful about using 2 or 3 liter soft bottles or water bottles or milk bottles for stor-ing chemicals. These types of plastic are not resistant to most chemicals. If you decide to use them be sure that you have taken the food label completely off the bottle and have labeled the bottle with a proper chemical label. Solutions of bases or salt solutions such as copper sulfate or sodium carbonate will develop leaks over a period of time in these bottles. One gallon heavy plastic vinegar bottles do work for storage.
Recycle empty bottles you purchase chemicals in such as acid bottles, alcohol bottles, etc. Be sure to completely remove the original label and properly label the solution you are storing in the bottle.
If you do not have how water piped into your lab, buy a 30 cup coffee pot with a spigot to use as a source of hot water.
Make coffee can or peanut butter jar desiccators by putting the desiccant in the bottom with a square of metal screen to top to set the test tubes or crucibles on.
Substitute paint thinner for solvents such as trichloro-trifluoroethane. This works well to
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Money Saving Tips To Teach Quality Chemis-try At Bargain Basement Prices
extract halogens from solution in single replacement reactions which formerly used CCl-4.
Use strawberry baskets, margarine tubs etc to help organize and store lab materials.
Plastic dish pans (such as Rubbermaid) make ideal lab trays and are much cheaper than the traditional lab trays.
Substitute 5 gallon water coolers with spigots for carboys to dispense distilled water.
One ounce and two ounce condiment cups from Sam’s are good weighing cups and also measuring devices for approximate amounts of liquid.
Plastic stirrers from airlines or fast food restaurants make ideal micro spatulas..
Seven mm “lead” for mechanical pencils makes excellent micro electrodes.
Plastic tennis cylinders can substitute for graduate cylinders in many demonstrations ex. Density cylinders.
Two electronic balance (.01 g approximately $300 to $400 or ,001 g approximately $800) serve a class of 24 better than 12 centigram balances (approximately $ 200 each).
Page protectors or acetate transparency sheets can substitute for micro well plates for many reactions.
Lengths of clear plastic tubing attached to a wood block with a rubber band can be used as a U-tube.
The top third of a 2 liter soft drink bottle can be used as a large funnel.
Hand held vacuum pumps and or aspirators on faucets can substitute for vacuum pumps in many experiments.
Use large glass fruit juice bottles with sand in the bottom to demonstrate the burning of steel wool in oxygen.
If your shop teacher has an oxygen or hydrogen cylinder with gauges you may be able so share the use and cost of having them filled. This is much cheaper than buying lecture bottles of gases.
Use drug store peroxides (from a discount store) for 3 % hydrogen peroxide. Clairoxide from the hair coloring section of the discount store is 6 % hydrogen peroxide as is “20 vol-ume” peroxide from a beauty supply store. “40 volume” peroxide is approximately 12 % peroxide.
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Money Saving Tips To Teach Quality Chemis-try At Bargain Basement Prices
Use yeast with 3 % peroxide to generate oxygen. It only takes a few grains and is much less mess than manganese dioxide.
Use large syringes for reduced pressure reaction. Your veterinarian might donate some of these especially if you have a dog and give him a lot of business.
Use grocery sore Borax to make Slime instead of sodium borate.
Buy dry cells at Sam’s or other discount stores or join the radio Shack battery club.
Used disposable communion cups can be collected and used as micro beakers.
Buy large 40 pound sacks of sodium chloride at the grocery store.
Toothpicks are good micro splints.
Paper cups, plastic bags, toothpicks, batteries, detergent, sponges, etc are usually much cheaper at the discount store or dollar store than the grocery store.
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Determination of the Molar Volume of Car-bon Dioxide Purpose: This activity could be carried out as an experiment or as a demonstration and is appropri-ate for a first-year college-prep or AP course. Using balloons and dry ice, students are able to determine the molar volume Of carbon dioxide at STP by making three mass measurements and recording the temperature and atmospheric pressure. Students will use the concept of buoyancy to determine the volume of the sample of gas and correct the molar volume to STP.
Description: By making measurements on a sample of carbon dioxide, students are able to determine the molar volume of CO2. They are also introduced to the concept of buoyancy and its importance when massing objects whose masses are small compared to their volumes. Demonstration: PV=nRT Pressure = Barometer C=2πd Volume= 4/3πr3
Materials: Chemicals: dry ice* Equipment: 15-inch round balloons * #5 solid rubber stoppers small beaker (100-mL or I50-mL) platform or top-loading centigram thermometer barometer or source of barometric pressure* hammer Towel See Modifications/Substitutions Hazards: Dry ice should not be touched with the bare hands; tissue damage can result. The recom-mended I5-inch balloons can hold up to about 1 mole of carbon dioxide gas; if a different size balloon is used, its capacity should be checked.
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The Dynamic Duo
Determination of the Molar Volume of Car-bon Dioxide Modifications/Substitutions: 1. Dry ice is available from ice companies or from an ice cream distributor or store. 2. Round balloons are available from a drugstore or party store. 3. The barometric pressure can be obtained by calling the number listed for weather in
most telephone directories. Procedure: 1. Mass a balloon and rubber stopper to the nearest hundredth of a gram and record. 2. While one student holds the mouth of the balloon open, another student should add
approximately 5-8 g of small pieces of dry ice to the balloon from a beaker and insert the stopper.
3. Quickly mass the balloon, stopper and dry ice as soon after assembling the system as possible.
4. Agitate the balloon and contents gently to vaporize the carbon dioxide. Dry the exterior of the balloon. Mass the balloon, stopper and gaseous carbon dioxide after the con-tents have reached room temperature.
5. Record the temperature of the room and the atmospheric pressure. 6. Calculate the mass of dry ice used. 7. Calculate the moles of carbon dioxide used. 8. Determine the mass of air displaced by the inflated balloon. (Mass of balloon, stopper, and C02 (s) - Mass of balloon, stopper, and CO2 (g)) / (Mass of displaced air) 9. Determine the volume of air displaced, using the density • of air at the temperature
and pressure in the room. 9. Volume of air displaced = (mass of air displaced / Density of air at room conditions) 10. Determine the volume of the carbon dioxide (volume of stopper is small enough com-
pared to the volume of the gas, that it can be ignored). Volume of CO2 = Volume of air displaced 11. Calculate the volume of carbon dioxide gas per mole of dry ice used. 11. Molar volume of CO2 (g) = (Volume of CO2/Mass of CO2) x (44 g CO2/Mole of CO2) 12. If it is assumed that the pressure of C02(g) in the balloon equals the atmospheric
pressure, the molar volume of CO2 can then be corrected to STP.
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The Dynamic Duo
Determination of the Molar Volume of Car-bon Dioxide Disposal: Carbon dioxide gas presents no disposal problems; it can be expelled from the balloons into the room. Discussion: When the apparent mass of the balloon, stopper and carbon dioxide gas is determined, it is much less than the mass of the system determined when the carbon dioxide was a solid. Because the volume of the balloon and gaseous contents is large compared to its mass, the mass of the displaced air, pushing against the balloon and buoying it up, is a significant fraction of the mass of the balloon and contents. The difference between the true mass of the balloon and contents and the apparent mass (when the carbon dioxide is a gas) is equal to the mass of the displaced air (the buoyancy correction). Using the mass of the displaced air and the density of air at room conditions (obtained from a handbook), students can calculate the volume of displaced air. The volume of displaced air is, to a good approximation, the volume of the carbon dioxide gas. Tips: 1. As part of the pre-activity discussion, show students the approximate volume of one
mole of gas by placing 44 g of dry ice in a IS-inch balloon and setting the balloon aside at the beginning of the period. By the end of class, the dry ice will have vapor-ized.
2. Students will need an understanding of buoyancy to understand this activity. It is sug-gested that teachers demonstrate buoyancy in water and discuss buoyancy in air as part of the pre-activity discussion. These ideas might be reinforced again while stu-dents are waiting for the dry ice to vaporize.
3. It is important that the massing of the balloon, stopper and dry ice be done as quickly as possible to minimize the buoyancy factor at this point. While waiting for the dry ice to vaporize,' students should be careful not to rub the balloon excessively; if the bal-loon picks up a static charge, it may interfere with the determination of the mass.
4. If 5-8 g of dry ice are vaporized in a I5-inch balloon attached to a manometer, the pressure exerted by the balloon fabric is 12-14 mm Hg. Since this pressure represents only about 1.5% of the total pressure, it is possible to approximate the pressure of the carbon dioxide with the atmospheric pressure without introducing substantial error.
5. If 5-8 g of carbon dioxide is placed in a 15-inch balloon, the measured molar volume is within 5% of the accepted value. Determining the volume of the balloon by measuring the circumference is not practical. Even if two or three circumference measurements are averaged, there is a 15-20% error in the molar volume because any error in the circumference is compounded when the radius is cubed to calculate the volume of the balloon.
Reference: "Handbook of Chemistry and Physics," The Chemical Rubber Publishing Co., Cleveland, OH. Use this reference to find the density of air at the temperature and pressure in the laboratory. Look up Density of Air in the index.
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The Dynamic Duo
Determination of the Molar Volume of Car-bon Dioxide
Submitted by Eva Lou Apel, Michael Bannon, Joseph Baron, John Brodemus, and Elna Clevenger, Consumer Chemicals, The Woodrow Wilson National Fellowship Foundation, Chemistry Institute, 1986 Curriculum Module
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The Dynamic Duo
Strong Acid + Strong Base
Strong Acid + Strong Base = pH 7 NaOH + HCl → NaCl (aq) + HOH H2O (l) H+ (aq) + OH- (aq) NaCl (s) → Na+ (aq) + Cl- (aq)
Na+
Na+
Na+
Na+
H+
H+
H+
OH-
OH-
OH-
Cl-
Cl-
Cl-
H2O
H2O H2O
[H+] = [OH-]
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The Dynamic Duo
Weak Acid + Strong Base
Weak Acid + Strong Base = pH > 7 HC2H3O2 + NaOH NaC2H3O2 + H2O NaC2H3O2 (s) Na+ (aq) + C2H3O2
- (aq) H2O (l) H+ (aq) + OH- (aq) HC2H3O2 (l) H+ (aq) + C2H3O2
- (aq) NaOH (s) → Na+ (aq) + OH- (aq)
Na+ Na+ Na+
H+ H+ H+
C2H3O2-
C2H3O2-
H2O H2O H2O
OH-
OH-
OH-
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The Dynamic Duo
Weak Base + Strong Acid
Weak Base + Strong Acid = pH < 7 NH4OH + HCl NH4Cl + H2O NH4Cl (s) NH4
+ (aq) + Cl- (aq) H2O (l) H+ (aq) + OH- (aq) NH4
+ (aq) + OH- (aq) NH4OH (s) HCl (g) → H+ (aq) + Cl- (aq)
H+ Cl-
NH4+
NH4+
NH4+
NH4+ NH4
+
H+
H+ Cl-
Cl-
H+
H2O
OH- H2O
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The Dynamic Duo
Rainbow Cylinder
Description: A long-lasting colorful display of acid-base-buffer solutions is prepared by filling a cylinder with successive portions of reactants of increasing density. Materials: 1000 ml graduate cylinder Funnel with long rubber tubing attached 300 ml 0.2M ammonium hydroxide 300 ml 0.2 M ammonium acetate 300 ml 0.2 M acetic acid 4 grams ammonium acetate about 10 grams sodium chloride 75 ml approximately 0.5 M HCl Yamada’s Universal Indicator or purchased Universal Indicator (To make Yamada’s Universal Indicator Dissolve 0.0025 g of thymol blue powder, 0.6 g of methyl red powder, 0.030 g of bromthymol blue powder and 0.05 g of phenolphthalein powder in 50 ml of 95 % ethanol. Add 0.1 N NaOH until the mixture is green and dilute the resulting solution to 100 ml with distilled water,) Procedure: Prepare each of the following solutions. Solution # 1: Add enough Yamada’s indicator to 300 ml of 0.2 M ammonium hydroxide to
make the solution deep blue or purple. Solution # 2: Add enough Yamada’s indicator to 300 ml of 0.2 M ammonium acetate to
make the solution bright green. Solution # 3: Add enough Yamada’s indicator to 300 ml of 0.2 M acetic acid to produce a
red-orange solution. Dissolve approximately 4 grams of ammonium acetate to this solution.
Solution # 4: Add enough Yamaha’s indicator to the HCl to produce a bright red solution.
Add enough solid NaCl to make a near saturated solution.
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The Dynamic Duo
Rainbow Cylinder
Assembling the Rainbow Cylinder: Pour Solution # 1 into the graduate cylinder. Carefully insert the funnel with rubber tubing into the cylinder so that the bottom of the tubing is at the bottom of the cylinder. Slowly pour Solution # 2 through the funnel into the cylinder. Next slowly pour Solution # 3 through the funnel. Finally, pour Solution # 4 through the funnel. Carefully remove the tubing. If necessary carefully add a few drops of 6M NaOH to the very top of the cylinder with a Beral pipette to make the top a violet color. Using a long stirring rod, slightly stir the contents of the cylinder to achieve a “ROYGBIV” cylinder. Cover the top of the cylin-der with plastic film and set it where it will not be disturbed. Suggestions: With a little practice and slight adjustment of the amounts of NaOH and HCl solutions, a beautiful rainbow results. Remember to add indicator and salt to the solutions in the lower part of the cylinder to increase the density of Solution # 4. Avoid over mixing the solutions at the beginning so that the cylinder will last longer. If possible, set the cylinder where light from a window shines through it. Hazards: Acetic acid, hydrochloric acid, sodium hydroxide and ammonium hydroxide are all corro-sive the pH at the top will be >10 and at the bottom will be <4. Disposal: The final solution is approximately pH 7 and can be flushed down the drain with water. Discussion: This demonstration is truly one that lasts and last. I usually make it early in the year for open house. The colors gradually change to give more of one color and a more complete rainbow. It usually takes approximately two months for the cylinder to become all one color. I do not explain what it is to the students when if first appears. By the time we dis-cuss density, the students usually realize the solutions are of different densities. I also use this as a reference during the study of acids, bases and buffers. The differences in density cause the diffusion to be slow but the changes are also slowed by the buffering produced by the acetic acid-ammonium acetate and by the ammonium hydroxide-ammonium acetate interfaces. The ammonium acetate solution will have a pH of 7 (green) because the acetic acid Ka equals the Kb of ammonium hydroxide. When study-ing weak acids, weak bases and buffers, a good question for an AP class would be to ex-plain why the final color is green. Reference: Adapted from a demonstration presented by Roy D. Caton at the Woodrow Wilson Chem-
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The Dynamic Duo
Rainbow Cylinder
istry Institute, Princeton University, 1986. Gunther, W.B. “Density Gradient Columns for Chemical Displays”, Journal of Chemical Education, Easton PA, 1986 Vol. 62, p148. This reference describes several long-lasting colorful displays.
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The Dynamic Duo
Determination Of The Molecular Weight of CO2 Description: The purpose of this demonstration is to quickly show that the molecular weight of a gas can be determined by using the ideal gas law. The source of the gas is dry ice. The dem-onstration can be started at the beginning of the lesson and completed at the end of the lesson. The time for the demonstration takes less than 15 minutes. Materials: 16 inch round balloons – yellow works best Top – loading centigram balance # 5 solid rubber stopper Barometer or source of baro metric pressure dry ice thermometer hammer Large powder funnel gloves Long piece of string towel Meter stick paper cup Overhead transparencies and over head projector Procedure: 1. Mass a balloon and a rubber stopper and record. 2. Crush a small piece of dry ice into small pieces using hammer and gloves. 3. Tare a bathroom paper cup on the balance. Add small pieces of dry ice until you get a
mass of 8 to 10 grams to approximate the mass of CO2 . 4. Place a large powder funnel into the opening of the balloon and push pieces of dry ice
into the balloon through the funnel and quickly stopper the balloon. 5. Immediately mass the balloon containing the dry ice with the stopper in place. Record
the mass. 6. Proceed with the lesson until all of dry ice has sublimed. Yellow balloons are easy to
see through. You may agitate or put in pan of warm water to speed up sublimation. 7. Have a student help you place a string around the balloon to measure the circumfer-
ence. Place the string on the meter stick to get the measurement. Measure both di-rections and average circumference to eliminate error.
8. Record the barometric pressure and the room temperature or the temperature of the
water bath. 9. Calculate the Molecular Weight of CO2 using the ideal gas formula. See transparency
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The Dynamic Duo
Determination Of The Molecular Weight of CO2
master for calculations. You will also calculate the percent error. Suggestions: Blow up the balloon and let the air out before class to stretch the rubber. Lower percent errors have been found then the sample size is between 8 and 10 grams. A 15 or 16 inch balloon should be used. Hazards: Dry ice should not be touched with bare hands. Tissue damage can result. Disposal: Allow excess dry ice to sublime in a hood or well ventilated area. Discussion: It is assumed that the pressure of CO2 gas in the balloon equals the atmospheric pres-sure. It is best to use a balloon that has been completely blown up and stretched. If 5-8 grams of dry ice are vaporized in a 15 inch balloon and attached to a manometer, the pressure exerted by the balloon fabric is 12-13 mm Hg. Since the pressure represents about 1.5 % of the total pressure, it is possible to equate the atmospheric pressure with the pressure of CO2. It is important to weigh the balloon, stopper and dry ice as quickly as possible before a significant amount of the dry ice has sublimes. This is a simplified ver-sion of a lab described in the reference. Reference: Eva Lou Apel, Michael Bannon, Joseph Baron, John Brodemus and Elna Clevenger. “Determination of the Molar Volume of Carbon Dioxide,” CONSUMER CHEMICALS, the Woodrow Wilson National Fellowship Foundation Chemistry Institute 1986 Curriculum Module.
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The Dynamic Duo
Molecular Weight CO2
Ideal Gas Law: MW=mRT/PV R=0.0821l L-atm/mole-°K MW= Accepted MW CO2 = 44.01 g % error =
Weight of balloon, stopper & dry ice g
Weight of balloon + stopper g
Weight of dry ice g
Barometric pressure mm Hg
Barometric pressure atm
Circumference (C) cm
Radius (r)=C/2π cm
Volume=4/3 πr3 cm3
Volume L
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The Dynamic Duo
Can Shaker
Context: Carbonated drinks are under pressure. They have a gas, carbon dioxide, dis-solved in them. Releasing the pressure, agitation and heating make the gas come out of solution. Opening the can releases the pressure. Materials: a cold can of carbonated drink, small ruler Procedure: 1. Shake up the carbonated drink. 2. Tap hard up and down the sides with edge of ruler before opening. 3. Ask for volunteers to open can at their desk. 4. Open and observe. Questions: 1. What did you expect to happen? 2. What did happen? 3. How does this relate to Boyles Law? Explanation: The carbon dioxide comes out of solution when the can is shook. By tapping on the can with the ruler you bring the bubbles to the top of the can. When the can is opened, the gas is released first. Usually when a can is shaken the gas in the bubbles is throughout the can. When the can is opened and the pressure is released the Gas is the bubbles rushes out and takes the soda with it.
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The Dynamic Duo
Shaving in a Vacuum
Context: Boyles Law Materials: Vacuum pump and bell jar, shaving cream, blown-up balloon, Peeps candy Procedure: 1. Place a blob of shaving cream on the platform of a bell jar. 2. Close the system and draw a vacuum 3. Observe 4. Remove shaving cream with paper towel. 5. Repeat with partially blown-up balloon and then with peeps candy. Questions: 1. What is contained in the shaving cream, balloon and Peeps candy? 2. Describe the shaving cream before and after the vacuum is pulled. Explanation: The shaving cream, balloon and Peeps Candy contain air – a gas. Boyles Law- when the pressure decreases the volume decreases.
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The Dynamic Duo
Hints For Demos And Demo Shows
Choice of demonstrations
1. THINK SAFETY. Is the room ventilated? What hazards are involved? Does the audi-ence need to wear safety goggles? Is it a demo that should be done outside with stu-dents at a safe distance away? Are proper disposal methods available? Is a safety shield available? Is the teaching value or show value worth the risk involved? Some demos in reliable books such as Shakhashiri and Sumerlin and even in text books are too hazardous to do in a large group setting in our opinion.
2. Is the demo relatively easy to do? How many solutions and what quantities are in-volved? Is it important that solutions be measured with extreme accuracy? Must solu-tions be made at the last minute? Are the solutions shelf stable? Can the demonstra-tion be done in disposable plastic or does it require a lot of cleanup and a lot of glass-ware?
3. Is it easy to understand? Is it easy to explain? Does it help explain a relevant science concept?
4. Can it be adapted to the theme of the show? Many demos lend themselves to differ-ent themes for different seasons of the year.
5. Does the demo have eye appeal? Is it one that is particularly “exocharmic”?
6. Does the demo use methanol or ethanol? If so, the large bottle of alcohol must not be nearby or accessible to students. A student deciding to add more alcohol is one of the greater dangers for burns.
Presentation of Demos And Demo Shows
1. Pick a theme for the show and develop a script which ties the demos together and to
the theme.
2. Pack a box for each demo which contains everything needed for that demo. If possi-ble, measure solutions ahead of time and place them in small bottles ready to use. The box should have a checklist of things needed and instructions for performing the demo. Number the boxes in the order they will occur in the show.
3. The demo should be done in a large enough scale to be visible in the room. An ele-vated box sometimes makes the demo more visible. Light boxes can easily be con-structed to aid in visibility. A white background or a dark background sometimes aid visibility.
4. Keep the demo table uncluttered. Do not set the box on the table. Only the necessary materials should be on the table. Remove all glassware, etc for each demo as it is finished before starting the next demo.
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The Dynamic Duo
Hints For Demos And Demo Shows
5. If a reaction is slow be sure to have something planned to say to keep attention di-rected on the reaction.
6. Begin and end the show with a demo which is spectacular orattention getting. Mix slower reactions with high interest reaction.
7. Be sure that you and your students model safety by wearing goggles, scissors, etc.
8. Take along containers for liquid and solid waste, paper towels, extension cords, extra distilled water, tape, magic markers, scissors, etc.
9. Enjoy the show. Your enthusiasm is contagious.
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The Dynamic Duo
H-2
The Dynamic Duo
Rules for Writing Equations
1. Write down the reactants and products. If products are not know, predict them. Use skeletal equation.
2. Balance all formulas. Remember the diatomic elements (H O N Cl Br I F) must be writ-ten as diatomic. (H2 N2 02 F2 Cl2 Br2 I2)
3. Remember that after each formula is correctly written, no subscript can be added or changed.
4. Balance the equation by placing coefficients in front of the formulas, making more molecules.
5. Check to see that you have the same number of atoms of each element on each side of the equation.
Example 1: Solid sodium + liquid water yields sodium hydroxide (aq.) plus hydrogen gas. Example 2: Iron (III) oxide reacts with carbon monoxide to give iron and carbon dioxide Example 3: Calcium hydroxide + phosphoric acid yields calcium phosphate + water Example 4: Zinc + hydrochloric acid yields zinc chloride + hydrogen
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The Dynamic Duo
Rules for Writing Equations
Example 5: Aluminum nitrate + sodium hydroxide yields aluminum hydroxide + sodium nitrate Example 6: Oxygen gas plus nitrogen gas yields nitrogen dioxide gas. Example 7: Aqueous beryllium iodide plus aqueous tin (II) nitrate yields aqueous beryllium nitrate and solid tin (II). Example 8: Aqueous ammonium sulfate plus aqueous lead (II) chlorate yield aqueous ammonium chlorate and solid lead (II) sulfate.
H-4
The Dynamic Duo
Dimensional Analysis Problems
Dimensional analysis (sometimes called factor-label), is a method of problem solving that uses units to help set up problems to arrive at a correct solution. If this is your first contact with it, it may seem awkward or hard to use; however, it is the best way to solve a wide variety of problems. To apply this approach to convert a quantity expressed in one unit to another unit, you proceed as follows: • Find a relationship between the two units, using a reference table. For example, if
asked to convert between pressures in atmospheres and millimeters of mercury, you first locate in a reference table the relation: 1 atm = 760 mm Hg.
• Translate this relationship into a conversion factor. The relationship 1 atm: 760 mm Hg gives you two conversion factors: 1 atm/760 mm Hg and 760 mm Hg /1 atm.
• Multiply the original quantity by a conversion factor that cancels the unit you want to get rid of. If asked to convert a pressure in atmospheres, for example 3.5 atm, to milli-meters of mercury, you multiply by 760 mm Hg/1 atm so as to cancel the unit "atm."
3.5 atm X 760 mm Hg /1 atm = 2660 mm Hg
• If necessary, repeat this process, using successive conversion factors, until you obtain
the quantity in the desired units. • Reference Table for Problems:
1 hogshead = 7 firkins 1 mole = 6.02 x 1023 molecules 8 lardos = 7 fleas
18 potties = 1 firkin 1 torr = 1 mm Hg 1 erg = 1 x 10-7 J
140 potties = l puncheon 1 torr = 133.322 Pascal (Pa) 1 BTU = 1055 J
504 potties = 1 tun 1 atm = 760 torr 1 oz = 16 drams
15 groans = 1 grunt 1 calorie = 4.184 Joule (J) 1 dram = 27.343 grains
1 pain = 20 grunts 1mile = 5280 ft 1 pennyweight = 24 grains
1 hurt = 8 pains 1 rod = 5.50 yards 1 dram = 3 scruples
1 fot = 5 vum 1 furlong = 220 yards 1 pint = 4 gills
2 sop = 3 tuz 4 fardells = 1 nooke 4 quarts = 1 gallon
4 bef = 3 tuz 4 nookes = 1 yard 1 bushel = 4 pecks
9 fot = 2 bef 4 yards = 1 hide 1 peck = 8 quarts
1 in = 2.54 cm 1 liter = 1.057 qt 1 lb = 453.6 g
1 sack = 7 bips 1 mile = 1.609 km 1 lb = 16 oz
5 smacks = 1 bip 4 tolls = 3 smacks 12 tolls = 1 lardo
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The Dynamic Duo
Dimensional Analysis Problems
Examples 732 torr = ? Atmospheres (atm) How many minutes are in one year? 70 miles/hr = ? ft/sec Dimensional Analysis Exercise # 1 Show all work in dimensional analysis for the following problems. Do work on your own paper. Draw a box around your answer. 1. 752 torr = ? atm 2. 752 atm = ? torr 3. 251 calories = ? J 4. 345 J = ? BTU 5. 27 pecks = ? bushels 6. 345 J = ? erg 7. 25 grunts = ? groans 8. 221 yd = ? furlongs 9. 42.0 potties = ? puncheons 10. 8.00 tun = ? potties 11. 144 hogshead = ? firkins 12. 455 tuns = ? puncheon 13. 6.51 lb = ? drams 14. 785 drams = ? pennyweight 15. 21 nookes = ? hides 16. 545 fardells = ? yards
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The Dynamic Duo
Dimensional Analysis Problems
Dimensional Analysis Exercise # 2 Show all work in dimensional analysis for the following problems. Do work on your own paper. Draw a box around your answer. 1. 22.5 gallons = ? liters 2. 3542 calories = ? BTU 3. 23.4 pennyweight = ? dram 4. 2 hurts = ? groans 5. 8.00 hides = fardell 6. 144 hogshead = ? tun 7. 3500 BTU = ? kcalorie 8. 6.00 km = ? inch 9. 33 peck = ? gallons 10. 2.00 atm = ? Pa 11. 2.2 lb = ? pennyweight 12. 5.0 grains = ? g 13. 4 sop = ? vum 14. 90.0 miles/hr = ? ft/sec 15. 25 mile/gallon = ? km/liter 16. How many seconds are in 2 years? Dimensional Analysis Exercise # 3 Show all work in dimensional analysis for the following problems. Do work on your own paper. Draw a box around your answer. 1. 35 vum = ? fot 2. 55 bef = ? fot 3. 333 cm = ? mile 4. 345 liter = ? bushel 5. 32 tolls = ? sacks 6. 0.25 lardos = ? sacks 7. 49 fleas = ? tolls 8. 12 bips = ? fleas 9. pains = ? groans 10. 25 sop = ? bef 11. 88.0 km/hr = ? ft/sec 12. 186,000 miles/sec = ? miles/year 13. 2 moles = ? molecules 14. 5.4 x 109 molecules = ? moles 15. 240 BTU = ? erg 16. 15 km/liter = ? miles/ gallon
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The Dynamic Duo
Periodic Table with Electron Configurations
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The Dynamic Duo
1 1 1s
1
2 1s
2 2
3 2s1
4 2s2
5 2p1
6 2p2
7 2p3
8 2p4
9 2p5
10
2p6
3 11
3s
1 12
3s
2
13
3p
1 14
3p
2 15
3p
3 16
3p
4 17
3p
5 18
3p
6 4
19
4s1
20
4s2
21
3d1
22
3d2
23
3d3
24
3d4
25
3d5
26
3d6
27
3d7
28
3d8
29
3d9
30
3d10
31
4p
1 32
4p
2 33
4p
3 34
4p
4 35
4p
5 36
4p
6 5
37
5s1
38
5s2
39
4d1
40
4d2
41
4d3
42
4d4
43
4d5
44
4d6
45
4d7
46
4d8
47
4d9
48
4d10
49
5p
1 50
5p
2 51
5p
3 52
5p
4 53
5p
5 54
5p
6 6
55
6s1
56
6s2
71
5d1
72
5d2
73
5d3
74
5d4
75
5d5
76
5d6
77
5d7
78
5d8
79
5d9
80
5d10
81
6p
1 82
6p
2 83
6p
3 84
6p
4 85
6p
5 86
6p
6 7
87
7s1
88
7s2
103
6d1
104
6d2
105
6d3
106
6d4
107
6d5
108
6d6
109
6d7
110
6d8
111
6d9
112
6d10
ns
(n-1
)d
np
6 57
4f
1 58
4f
2 59
4f
3 60
4f
4 61
4f
5 62
4f
6 63
4f
7 64
4f
8 65
4f
9 66
4f
10
67
4f11
68
4f
12
69
4f13
70
4f
14
7 89
5f
1 90
5f
2 91
5f
3 92
5f
4 93
5f
5 94
5f
6 95
5f
7 96
5f
8 97
5f
9 98
5f
10
99
5f11
10
0 5f
12
101
5f13
10
2 5f
14
(n-2
)f
Perio
dic
Cha
rt &
Ele
ctro
n C
onfig
urat
ion
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The Dynamic Duo
1
2
3
4
5
6
7
6
7
