Syllabus Chemistry 101 Fall 2009Sec. 501 (MWF 8:00-8:50) Sec 505 (MWF 12:40-1:30) RM

100 HELDProfessor: Dr. Earle G. Stone

Office: Room 123E Heldenfels (HELD) Telephone: 845-3010 (no voice mail) or leave a message at 845-

2356email: estone@tamu.edu

(put CHEM 101-Sec. # + subject in subject line of your email)Office Hours: HELD 123E: Tue. And Thur. 8:00-10:50 AM

I.A. TBA S.I. Leader: TBA

CHEM 101 and 102 are the first-year chemistry sequence in the core curriculum. These are 3-credit courses. All lecture sections strive to cover common content. The lecture component of Chemistry 101 covers stoichiometry, atomic and molecular structure, chemical bonding, fundamental acid/base chemistry, solution chemistry, properties of liquids and solids, the gas laws, and this class will additionally cover foundation work in inorganic and organic nomenclature and structure, including some mention of major biological organic and inorganic compounds.

More importantly, it is the goal of my lecture section to help you develop the skill set to successfully complete your undergraduate degree and as most in this class are pre-something to prepare for your professional school entrance exam and enable you to succeed in your choice of professional school.

Helpful Online Dictionary of

Chemistry Useful As A Second Language

General Chemistry I

and Organic Chemistry I

(There are O-chem II and Physics books in this series if you find these

useful and will have to take those classes.

Hardbound ~$200Solution Manual ~$40Online Tutor ~$45

Total ~$285

Ebook $45 per semesterIncludes

TextSolution manualOnline tutorial

Yvette FreemanPublisher's Representative

Pearson Education

Chang’s Essentials

Kotz and Treichel 7th ed. TEXTBOOKS Averill and Eldridge

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Grading:Your grade will be based on

•Four one-hour examinations (each worth 200 points) •A final examination (400 points)

There are no bonuses, no extra credit, no soft points

Major Examination Schedule Fall 2005:Wed. Sept. 16 Major Exam No.1Wed. Oct. 7 Major Exam No.2Mon. Nov. 9 Major Exam No.3Fri. Dec. 4 Major Exam No. 4

Fri. Dec. 11 Section 501 Final Exam 10:00 to 12:00Mon. Dec. 14 Section 506 Final Exam 10:30 to 12:30

1) Raw scores are determined. 1) Raw scores are determined. Sum of points assigned to correct responses2) Individual scores are normalized. 2) Individual scores are normalized. A context-free evaluation of relative performance3) Normalized scores are transformed. 3) Normalized scores are transformed. An absolute score is assigned to a defined scale4) Letter grades are assigned4) Letter grades are assigned >89.451 A

>79.451 B >69.451 C >59.451 D <59.451 F

The way the real world The way the real world worksworksIndividual Mastery Individual Mastery compared compared to a large populationto a large populationWhat you are used to and What you are used to and I willI willreportreport  Normal Exam 1 Exam 2 Exam 3 Exam 4 Final

>3 1 0 0 0 0 0>2 10 4 3 5 4 8>1 61 78 73 75 64 67>0 154 146 163 146 175 151<0 154 154 134 156 133 145<-1 61 56 65 58 59 73<-2 10 12 12 10 15 8<-3 1 2 2 2 2 0

How grades are determinedHow grades are determined

Problem - Problem - A situation that presents difficulty, uncertainty, or A situation that presents difficulty, uncertainty, or perplexity: perplexity:

The mere formulation of a problem is far more often essential The mere formulation of a problem is far more often essential than its solution, which may be merely a matter of mathematical than its solution, which may be merely a matter of mathematical or experimental skill. To raise new questions, new possibilities, to or experimental skill. To raise new questions, new possibilities, to regard old problems from a new angle requires creative regard old problems from a new angle requires creative imagination and marks real advances in science. imagination and marks real advances in science. ~~Albert Albert EinsteinEinstein

Question - Question - A request for data: inquiry, A request for data: inquiry, interrogation, query. interrogation, query.

Answer - Answer - A spoken or written reply, as to A spoken or written reply, as to a question.a question.

Solution - Solution - Something worked out to explain, Something worked out to explain, resolve, or provide a method for resolve, or provide a method for dealing with and settling a problem.dealing with and settling a problem.

And we begin:And we begin:

Scientific Method - Scientific Method - A procedure that A procedure that searches for answers to questions and searches for answers to questions and solutions to problems, which consists of:solutions to problems, which consists of:

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http://museum.nist.gov/exhibits/adx2/index.htm

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http://www.patentstorm.us/patents/5945236-description.html

• Can be Can be qualitative qualitative or or quantitative quantitative • Qualitative observations Qualitative observations describe properties or occurrences describe properties or occurrences

in ways that do not rely on numbers. in ways that do not rely on numbers. • Quantitative observations Quantitative observations are measurements that consist of are measurements that consist of

a number a unit and a labela number a unit and a label

ObservationsObservations

HypothesesHypotheses• A tentative explanation for the observations that may not be A tentative explanation for the observations that may not be

correct, but puts the scientist’s understanding of the system correct, but puts the scientist’s understanding of the system being studied into a form that can be testedbeing studied into a form that can be testedExperimentsExperiments

• Tests the validity of the hypothesisTests the validity of the hypothesis• Are systematic observations or measurements made under Are systematic observations or measurements made under

controlled conditions, in which the variable of interest is clearly controlled conditions, in which the variable of interest is clearly distinguished from any othersdistinguished from any others

• If experimental results are reproducible, they are summarized If experimental results are reproducible, they are summarized in a in a law.law.

• A verbal or mathematical description of a phenomenon that A verbal or mathematical description of a phenomenon that allows for general predictions that describes allows for general predictions that describes what what happens happens and not and not why why and is unlikely to change greatly over time and is unlikely to change greatly over time unless a major experimental error is discovered. unless a major experimental error is discovered.

• Attempts to explain Attempts to explain why why nature behaves as it does which is nature behaves as it does which is incomplete and imperfect and evolves with time to explain incomplete and imperfect and evolves with time to explain new facts as they are discoverednew facts as they are discovered

Law Law

Theory Theory

Natural LawsNatural Laws• Law of Conservation of Mass – Law of Conservation of Mass – The notion The notion

that mass, or matter, can be neither created nor destroyed.that mass, or matter, can be neither created nor destroyed.

• Law of Conservation of Energy – Law of Conservation of Energy – A law that A law that states that in any system not involving nuclear reactions or velocities states that in any system not involving nuclear reactions or velocities approaching the velocity of light, energy cannot be created or destroyed. approaching the velocity of light, energy cannot be created or destroyed. The First Law of Thermodynamics.The First Law of Thermodynamics.

• Law of Conservation of Mass – Energy Law of Conservation of Mass – Energy – –

Einstein’s General Theory of Relativity - E=mc- E=mc2 2 – with work becomes the – with work becomes the special theory of relativity, which has been verified by experiment, has special theory of relativity, which has been verified by experiment, has shown that the mass of a body changes as the energy possessed by the body shown that the mass of a body changes as the energy possessed by the body changes. Such changes in mass are too small to be detected except in changes. Such changes in mass are too small to be detected except in subatomic phenomena. Matter may be created by the materialization of a subatomic phenomena. Matter may be created by the materialization of a photon into an electron-positron pair; or it may be destroyed, by the photon into an electron-positron pair; or it may be destroyed, by the annihilation of this pair of elementary particles to produce a pair of annihilation of this pair of elementary particles to produce a pair of photons. photons.

Law of Definite Proportions – Law of Definite Proportions – When two or more elements combine to form a compound, their masses in that compound are in a fixed and definite ratio. This data helps justify an atomic view of matter.

Law of Multiple Proportions – Law of Multiple Proportions – When two elements combine to form more than one compound, the mass of element A which combines in the first compound with a given amount of element B has a simple whole number ratio with the mass of element A which combines in the second compound with the same given mass of element B.

Natural LawsNatural Laws

Dr. Stone’s patent pending chemistry problem Dr. Stone’s patent pending chemistry problem solversolver

1.1. Write down everything you are Write down everything you are givengiven

•VocabularyVocabulary•NumbersNumbers•UnitsUnits

2.2. Write down what you want to Write down what you want to knowknow

•VocabularyVocabulary•NumbersNumbers•UnitsUnits

3.3. Write down mathematical Write down mathematical equation(s) that include(s) equation(s) that include(s) these values and unitsthese values and units

•PrinciplesPrinciples

4.4. Write a balanced Write a balanced stoichiometric equationstoichiometric equation

•Mole conceptMole concept

5.5. Convert everything to molesConvert everything to moles•DimensionalDimensional analysisanalysis

6.6. Convert everything to the Convert everything to the unknown’s unitsunknown’s units

•Rounding, significant figures, Rounding, significant figures, accuracy and precisionaccuracy and precision

(m)c (ms-1)E =

[C]c[D]d

[A]a[D]b

Use of NumbersUse of Numbers• Exact numbersExact numbers

– 1 dozen = 12 things for example1 dozen = 12 things for example• Accuracy Accuracy

– how closely measured values agree with the correct valuehow closely measured values agree with the correct value• PrecisionPrecision

– how closely individual measurements agree with each otherhow closely individual measurements agree with each other• Significant Figures – start at the left and proceed to the rightSignificant Figures – start at the left and proceed to the right

– If the number does not have a decimal point count until there are If the number does not have a decimal point count until there are no more non zero numbersno more non zero numbers

– If the number has a decimal point start counting at the first non-If the number has a decimal point start counting at the first non-zero number and continue counting until you run out of decimal zero number and continue counting until you run out of decimal placesplaces

• Scientific notation – use it.Scientific notation – use it.

Use of NumbersUse of Numbers

• Addition & Subtraction ruleAddition & Subtraction rule

More subtle than the multiplication ruleMore subtle than the multiplication rule

Answer contains smallest decimal place of the addends.Answer contains smallest decimal place of the addends.

6.95 tooff round

9463.6

20.2

423.1

3692.3

6.671 tooff round

6707.6

312.2

7793.8

When a 5 appears. Is there anything to the right of the 5 greater than zero?Is the number to the left of the 5 odd?Is the number to the left of the 5 even? (Treat 0 as even.)

• Multiplication & Division rule Multiplication & Division rule

Easier of the two rulesEasier of the two rules

Product has the smallest number of significant figures of Product has the smallest number of significant figures of multipliersmultipliers

5.22 tooff round

21766.5

31.2x

224.4

3.9 tooff round

89648.3

41.x

2783.2

How many sig figs?a)0.0713200b)7843000c)1.4800d)100e)100.0f)894.003g)89400h)0.03000i)74.000

How many sig figs in the answer?a)472x101b)4600x0.005c)36.0x4752d)45.08/36.2e)1.003/8500f)0.003/472x12g)3.003/475.0x0.30/524h)0.3005x4.1i)23.56+24.983j)4.78-2.892k)46.83-0.03l)34.892+5.0m)134.033-0.02n)48.2-46

Round off to two sig figsa)34.78b)17.51c)48.50d)45.50001e)24.33f)17.50g)20.5h)45.5000

(1.68)[ ]23.56 – 2.31.248 x 103

=

Use of NumbersUse of Numbers

VocabularyVocabulary• ChemistryChemistry - - Science that describes matter – its properties-composition-structure, the changes it

undergoes, and the energy changes that accompany those processes

• Matter - Matter - Anything that has mass and occupies space.

• Energy -Energy - The capacity to do work or transfer heat.• Chemical Properties - Chemical Properties - chemical changes - describes the characteristic ability of a substance to

react to form new substances (flammability and corrosion). – rusting or oxidation, chemical reactions

• Physical Properties - Physical Properties - physical changes - Characteristics that scientists can measure without changing the composition of the sample under study (mass, color, volume, amount of space occupied by the sample).– changes of state, density, color, solubility

• Extensive Properties - Extensive Properties - depend on quantity a. Vary with the amount of the substancea. Vary with the amount of the substance b. Include mass, weight, and volume.b. Include mass, weight, and volume.

• Intensive Properties Intensive Properties - - do not depend on quantity a. a. Include color, melting and boiling point, electrical conductivity, and physical state at a given

temperature b. Determine a substance’s identity, c. Have an important intensive property called density (d), a ratio of two extensive properties, mass and volume

density = mass d = m

volume V

• Three distinct Three distinct states of matter:states of matter:

1. Solids — 1. Solids — relatively rigid and have fixed shapes and relatively rigid and have fixed shapes and volumes volumes

— — volumes of solids independent of temperature volumes of solids independent of temperature and pressureand pressure

2. Liquids — 2. Liquids — have fixed volumes but flow to assume the shape have fixed volumes but flow to assume the shape of their containersof their containers

— — Volumes of liquids independent of Volumes of liquids independent of temperature and pressuretemperature and pressure

3. Gases — 3. Gases — have neither fixed shapes nor fixed volumes and have neither fixed shapes nor fixed volumes and expand to fill their containers completelyexpand to fill their containers completely

— — Depends strongly on temperature and Depends strongly on temperature and pressure pressure

VocabularyVocabulary

Vocabulary Vocabulary –– Isotopes and Isotopes and Atomic MassesAtomic Masses

Atoms of different elements Atoms of different elements exhibit different chemical exhibit different chemical behavior.behavior.

Identity of an element is defined Identity of an element is defined by its by its atomic number. atomic number.

(Z) is the number of protons in (Z) is the number of protons in the nucleus of an atom of the the nucleus of an atom of the element.element.

The atomic number is therefore The atomic number is therefore different for each element.different for each element.

Known elements are arranged Known elements are arranged in order of increasing Z in the in order of increasing Z in the periodic table.periodic table.

Vocabulary Vocabulary –– Isotopes and Atomic Isotopes and Atomic MassesMasses The chemistry of each element is determined by its number The chemistry of each element is determined by its number

of protons and electrons.of protons and electrons. In a neutral atom, the number of electrons equals the In a neutral atom, the number of electrons equals the

number of protons.number of protons. Symbols for elements are derived directly from the Symbols for elements are derived directly from the

element’s name.element’s name. Nuclei of atoms contain neutrons as well as protons.Nuclei of atoms contain neutrons as well as protons. The number of neutrons is not fixed for most elements, The number of neutrons is not fixed for most elements,

unlike protons.unlike protons. Atoms that have Atoms that have the same number of protons, the same number of protons, and hence and hence

the same atomic number, but the same atomic number, but different numbers of neutrons different numbers of neutrons are called are called isotopesisotopes. .

Isotopes - Isotopes - All isotopes of an element have the same number All isotopes of an element have the same number of protons and electrons, which means they exhibit the of protons and electrons, which means they exhibit the same chemistry. Isotopes of an element differ only in their same chemistry. Isotopes of an element differ only in their atomic mass.atomic mass.

• • Atomic massAtomic mass 1. 1. The mass of any given atom is not simply the sum of the masses The mass of any given atom is not simply the sum of the masses

of its electrons, protons, and neutrons.of its electrons, protons, and neutrons.

2. Atoms are too small to measure individually and do not have a 2. Atoms are too small to measure individually and do not have a charge.charge.

3. The arbitrary standard that has been established for describing 3. The arbitrary standard that has been established for describing atomic mass is the atomic mass unit (amu), defined as one-atomic mass is the atomic mass unit (amu), defined as one-twelfth of the mass of one atom of twelfth of the mass of one atom of 1212C.C.

4. Most elements exist as mixtures of several stable isotopes. The 4. Most elements exist as mixtures of several stable isotopes. The weighted average is of the masses of the isotopes is called the weighted average is of the masses of the isotopes is called the atomic mass. atomic mass.

5. Electrons added or removed from an atom produce a charged 5. Electrons added or removed from an atom produce a charged particle called an particle called an ion,ion, whose charge is indicated by a superscript whose charge is indicated by a superscript after the symbol for the element. after the symbol for the element.

Vocabulary Vocabulary –– Isotopes and Atomic Isotopes and Atomic MassesMasses

Vocabulary Vocabulary –– Essential ElementsEssential Elements• Elements that are absolutely required in the diets of humans Elements that are absolutely required in the diets of humans

are called essential elements (highlighted in purple).are called essential elements (highlighted in purple).

• Essential elements are restricted to the first four rows of the Essential elements are restricted to the first four rows of the periodic table with only two exceptions (Mo and periodic table with only two exceptions (Mo and ).).

• An essential element is one that is required for life and An essential element is one that is required for life and whose absence results in death.whose absence results in death.

• An element is considered to be essential if a deficiency An element is considered to be essential if a deficiency consistently causes abnormal development or functioning consistently causes abnormal development or functioning and if dietary supplementation of that element and only that and if dietary supplementation of that element and only that element prevents this adverse effect.element prevents this adverse effect.

Classification of the Essential Classification of the Essential ElementsElements

• Most living matter consists primarily of Most living matter consists primarily of bulk bulk elements—elements—oxygen, carbon, hydrogen, nitrogen, oxygen, carbon, hydrogen, nitrogen, and sulfur. They are the building blocks of the and sulfur. They are the building blocks of the compounds that make up our organs and compounds that make up our organs and muscles; they also constitute the bulk of our muscles; they also constitute the bulk of our diet.diet.

• Six elements—sodium, magnesium, potassium, Six elements—sodium, magnesium, potassium, calcium, chlorine, and phosphorus—are called calcium, chlorine, and phosphorus—are called macromineralsmacrominerals and provide essential ions in and provide essential ions in body fluids and form the major structural body fluids and form the major structural components of the body.components of the body.

• Remaining essential elements called Remaining essential elements called trace trace elements elements and are present in small amounts.and are present in small amounts.

The Trace ElementsThe Trace Elements• It is difficult to detect low levels of some of the It is difficult to detect low levels of some of the

essential elements, so the trace elements were essential elements, so the trace elements were relatively slow to be recognized.relatively slow to be recognized.

• Many compounds of trace elements are toxic.Many compounds of trace elements are toxic.• Dietary intakes of elements range from deficient to Dietary intakes of elements range from deficient to

optimum to toxic with increasing quantities; the optimum to toxic with increasing quantities; the optimum levels differ greatly for the essential optimum levels differ greatly for the essential elements.elements.

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Chemical CompoundsChemical Compounds

Atoms in all substances that contain more than one atom are held together by electrostatic interactions—interactions between electrically charged particles such as protons and electrons.

Compounds & MoleculesCompounds & Molecules• COMPOUNDS COMPOUNDS are a combination of 2 or more are a combination of 2 or more

elements in definite ratios by mass. elements in definite ratios by mass. (Law of (Law of Definite Proportions)Definite Proportions)

• The character of each element is lost when The character of each element is lost when forming a compound.forming a compound.

• MOLECULESMOLECULES are the smallest unit of a are the smallest unit of a compound that retains the characteristics of compound that retains the characteristics of the compound. the compound.

The composition of molecular compounds is The composition of molecular compounds is given by agiven by a

• CHEMICAL FORMULACHEMICAL FORMULA

WRITING FORMULASWRITING FORMULASWRITING FORMULASWRITING FORMULAS

The The structural chemical structural chemical formula for formula for glycine can be written as glycine can be written as

HH22NCHNCH22COOHCOOH

to show atom orderingto show atom ordering

or in the bond-line structural formulaor in the bond-line structural formula

C

H

H C

H

H

O

O HN

Chemical Formula – Chemical Formula – chemical symbols and number of each chemical symbols and number of each representing compositionrepresenting composition Empirical Formula – Empirical Formula – simplest ratio of elements that does not simplest ratio of elements that does not represent the actual represent the actual number and is non-positionalnumber and is non-positional Molecular Formula – Molecular Formula – chemical symbols and number of each chemical symbols and number of each representing representing composition representing actual number composition representing actual number but not positionbut not position Structural Formula – Structural Formula – chemical symbols and number of each chemical symbols and number of each representing representing composition representing actual number composition representing actual number and positionand position

Enables chemists to create a three-dimensional model that provides information about the physical and chemical properties of the compound

Empirical and molecular formulas are precise Empirical and molecular formulas are precise and informative but have disadvantages:and informative but have disadvantages: – – inconvenient for routine verbal communicationsinconvenient for routine verbal communications

– – many compounds have the same empirical and many compounds have the same empirical and molecular formulas but different arrangements of molecular formulas but different arrangements of atoms, which results in different chemical and atoms, which results in different chemical and physical propertiesphysical properties

WRITING FORMULASWRITING FORMULASWRITING FORMULASWRITING FORMULAS

STRUCTURAL FORMULA

BOND-LINE FORMULA

Compounds & MoleculesCompounds & Molecules

MOLECULAR FORMULASMOLECULAR FORMULASMOLECULAR FORMULASMOLECULAR FORMULAS

•In one molecule of glycine there areIn one molecule of glycine there are

– 2 C atoms2 C atoms– 5 H atoms5 H atoms– 1 N atom1 N atom– 2 O atoms2 O atoms

Empirical Formula _______________Empirical Formula _______________

Molecular Formula _______________Molecular Formula _______________

Structural Formula _______________Structural Formula _______________

Representations of Molecular Representations of Molecular StructuresStructures Different ways of representing the Different ways of representing the

structure of a moleculestructure of a molecule

1.1.Molecular formula gives only the number of each kind Molecular formula gives only the number of each kind of atom present.of atom present.

2.2.Structural formula shows which atoms are present and Structural formula shows which atoms are present and how they are connected.how they are connected.

3.3.Ball and stick model shows the atoms as spheres and Ball and stick model shows the atoms as spheres and the bonds as sticks.the bonds as sticks.

4.4.A perspective drawing, called a A perspective drawing, called a wedge-and-dashwedge-and-dash representation,representation, attempts to show the three-dimensional attempts to show the three-dimensional structure of the molecule. structure of the molecule.

5.5.The space-filling model shows the atoms in the The space-filling model shows the atoms in the molecule but not the bonds. molecule but not the bonds.

6.6.The condensed structural formula is the easiest and The condensed structural formula is the easiest and most common way to represent a molecule—it omits the most common way to represent a molecule—it omits the lines representing bonds between atoms and simply lines representing bonds between atoms and simply lists the atoms bonded to a given atom next to it. lists the atoms bonded to a given atom next to it. Multiple groups attached to the same atom are shown Multiple groups attached to the same atom are shown in parentheses, followed by a subscript that indicates in parentheses, followed by a subscript that indicates the number of such groups.the number of such groups.

1.

2.

3.

4.

5.

6.

Chemical Compounds Chemical Compounds • Chemical bondsChemical bonds – – two different kindstwo different kinds

1. Ionic —1. Ionic — ionic compounds consist of positively and ionic compounds consist of positively and negatively negatively charged ions held together by strong electrostatic forces. charged ions held together by strong electrostatic forces. (Formula Mass)(Formula Mass)

2. Covalent — 2. Covalent — covalent compounds consist of molecules, which are covalent compounds consist of molecules, which are groups of atoms in which one or more pairs of electrons groups of atoms in which one or more pairs of electrons are shared between bonded atoms. Atoms are held are shared between bonded atoms. Atoms are held together by the electrostatic attraction between the together by the electrostatic attraction between the positively charged nuclei of the bonded atoms and the positively charged nuclei of the bonded atoms and the negatively charged electrons they share. (Molecular Mass)negatively charged electrons they share. (Molecular Mass)

Ionic Chemical Compounds Ionic Chemical Compounds • Electrostatic attraction Electrostatic attraction between oppositely charged particle between oppositely charged particle

species (positive and negative) results in a force that causes species (positive and negative) results in a force that causes them to move toward each other.them to move toward each other.

• Electrostatic repulsion Electrostatic repulsion between two species that have the between two species that have the same charge (either both positive or both negative) results in a same charge (either both positive or both negative) results in a force that causes them to repel each otherforce that causes them to repel each other

• When the attractive electrostatic interactions between atoms When the attractive electrostatic interactions between atoms are stronger than the repulsive interactions, atoms form are stronger than the repulsive interactions, atoms form chemical compoundschemical compounds and the attractive interactions between and the attractive interactions between atoms are called atoms are called chemical bondschemical bonds..

• IONSIONS are atoms or groups of atoms with a net positive or are atoms or groups of atoms with a net positive or negative charge. negative charge.

• Taking awayTaking away an electron from an atom gives a an electron from an atom gives a CATIONCATION with a with a positive chargepositive charge

• AddingAdding an electron to an atom gives an an electron to an atom gives an ANIONANION with a with a negative chargenegative charge..

• Ionic compounds contain both cations and anions in a ratio that results in no net electrical charge.In generalIn general

metals (Mg) lose electrons metals (Mg) lose electrons tto become cationscations

nonmetals (F) gain electrons nonmetals (F) gain electrons tto become anionsanions

Ionic Chemical CompoundsIonic Chemical Compounds

Ionic compounds are held together by the Ionic compounds are held together by the attractive electrostatic interactions between attractive electrostatic interactions between cationscations and and anionsanions. . CationsCations and and anionsanions are arranged in space to are arranged in space to form an extended three-dimensional array form an extended three-dimensional array that maximizes the number of attractive that maximizes the number of attractive electrostatic interactions and minimizes the number of repulsive electrostatic interactions and minimizes the number of repulsive electrostatic interactions.electrostatic interactions.

• A neutral compound requires equal number of + and - charges.A neutral compound requires equal number of + and - charges.

CATIONCATION + + ANIONANION → COMPOUND → COMPOUND

Physical Properties of Ionic Physical Properties of Ionic CompoundsCompounds Ionic compoundsIonic compounds

– – Usually form hard crystalline solids that melt at Usually form hard crystalline solids that melt at high temperatures and are very resistant to high temperatures and are very resistant to evaporationevaporation

– – Properties stem from the characteristic internal Properties stem from the characteristic internal structure of an ionic solid, which is a three-structure of an ionic solid, which is a three-dimensional array of alternating positive and dimensional array of alternating positive and negative ions held together by strong negative ions held together by strong electrostatic attractions electrostatic attractions

PbSPbS

FeSFeS

SiOSiO

An ionic compound that contains only two An ionic compound that contains only two elements, one present as a cation and one elements, one present as a cation and one as an anion, is called a as an anion, is called a binary ionic binary ionic compound.compound.

For such compounds, the subscripts in the For such compounds, the subscripts in the empirical formula can also be obtained empirical formula can also be obtained using the absolute value of the charge on using the absolute value of the charge on one ion as the subscript for the other ion one ion as the subscript for the other ion and then reduce the subscripts to their and then reduce the subscripts to their simplest ratio to write the empirical simplest ratio to write the empirical formula.formula.

Binary Ionic CompoundsBinary Ionic Compounds

Groups of atoms that bear a net electrical Groups of atoms that bear a net electrical chargecharge

Atoms that make up a polyatomic atom are Atoms that make up a polyatomic atom are held together by the same covalent bonds that held together by the same covalent bonds that hold atoms together in moleculeshold atoms together in molecules

Many more kinds of polyatomic ions than Many more kinds of polyatomic ions than monatomic ions and polyatomic anions are monatomic ions and polyatomic anions are more numerous than polyatomic cationsmore numerous than polyatomic cations

Method used to predict empirical formula for Method used to predict empirical formula for ionic compounds that contain monatomic ions ionic compounds that contain monatomic ions can be used for compounds containing can be used for compounds containing polyatomic ions. Overall charge on the polyatomic ions. Overall charge on the cations must balance the overall charge on cations must balance the overall charge on the anions in the formula unit.the anions in the formula unit.

Polyatomic IonsPolyatomic Ions

Monovalent Divalent Trivalent

Hydronium H3O+ Magnesium Mg2+ Aluminium Al3+

(or hydrogen) H+ Calcium Ca2+ Antimony III Sb3+

Lithium Li+ Strontium Sr2+ Bismuth III Bi3+

Sodium Na+ Beryllium Be2+

Potassium K+ Manganese II Mn2+

Rubidium Rb+ Barium Ba2+

Cesium Cs+ Zinc Zn2+

Francium Fr+ Cadmium Cd2+

Silver Ag+ Nickel II Ni2+

Ammonium NH4+ Palladium II Pd2+

Thalium Tl+ Platinum II Pt2+

Copper I Cu+ Copper II Cu2+

Mercury II Hg2+

Mercury I Hg22+

Iron II Fe2+ Iron III Fe3+

Cobalt II Co2+ Cobalt III Co3+

Chromium II Cr2+ Chromium III Cr3+

Lead II Pb2+

Tin II Sn2+

Table of Common IonsTable of Common IonsCommon Positive Ions (Cations)Common Positive Ions (Cations)

Monovalent Divalent TrivalentHydride H- Oxide O2- Nitride N3-

Fluoride Fl- Peroxide O22-

Chloride Cl- Sulfide S2-

Bromide Br- Selenide Se2-

Iodide I- Oxalate C2O42-

Hydroxide OH- Chromate CrO42-

Permangante MnO4- Dichromate Cr2O7

2-

Cyanide CN- Tungstate WO42-

Thiocynate SCN- Molybdate MoO42-

Acetate C2H3O2- tetrathionate S4O6

2-

Nitrate NO3- Thiosulfate S2O3

2-

Bisulfite HSO3- Sulfite SO3

2-

Bisulfate HSO4- Sulfate SO4

2-

Bicarbonate HCO3- Carbonate CO3

2-

Dihydrogen phosphate H2PO4- Hydrogen phosphate HPO4

2- Phosphate PO43-

Nitrite NO2-

Amide NH2-

Hypochlorite ClO-

Chlorite ClO2-

Chlorate ClO3-

Perchlorate ClO4-

Table of Common Ions Table of Common Ions Common Negative Ions (Anions)Common Negative Ions (Anions)

Ionic compounds that Ionic compounds that contain specific ratios of contain specific ratios of loosely bound water loosely bound water molecules, called molecules, called waters of waters of hydration.hydration.

Waters of hydration can be Waters of hydration can be removed by heating.removed by heating.

Compounds that differ only Compounds that differ only in the numbers of waters of in the numbers of waters of hydration can have very hydration can have very different properties.different properties.

HydratesHydrates

Prefixes for indicating numbers of species in

chemical names

Prefix Number

Prefix Number

mono -

1 hepta- 7

di- 2 octa- 8

tri- 3 nona- 9

tetra- 4 deca- 10

penta- 5 undeca-

11

hexa- 6 dodeca-

12

Naming Polyatomic Ionic Naming Polyatomic Ionic CompoundsCompounds

Naming Polyatomic Ionic Naming Polyatomic Ionic CompoundsCompounds

Write the names of the compound as the name of the Write the names of the compound as the name of the cation followed by the name of the anion.cation followed by the name of the anion.

– It is not necessary to indicate the number of cations or anions present per formula unit in the name of an ionic compound because information is implied by the charges on the ions– When writing the formula for an ionic compound from its name the charge of the ions must considered.

Covalent CompoundsCovalent Compounds Physical Properties of Covalent Physical Properties of Covalent

compoundscompounds

– – Can be gases, liquids, or solids at room Can be gases, liquids, or solids at room temperature and temperature and pressure, depending pressure, depending on the strength of the intermolecular on the strength of the intermolecular interactionsinteractions

– – Covalent molecular solids tend to form Covalent molecular solids tend to form soft crystals that soft crystals that melt at low melt at low temperatures and evaporate easilytemperatures and evaporate easily

– – Consist of discrete molecules held Consist of discrete molecules held together by comparatively weak together by comparatively weak intermolecular forces (the forces between intermolecular forces (the forces between molecules) even though the atoms within molecules) even though the atoms within each molecule are held together by strong each molecule are held together by strong intramolecular covalent bonds (the forces intramolecular covalent bonds (the forces within the molecule) within the molecule)

Covalent CompoundsCovalent Compounds• Covalent compound are represented by a Covalent compound are represented by a molecular molecular

formulaformula, which gives the atomic symbol for each , which gives the atomic symbol for each component element, in a prescribed order, accompanied component element, in a prescribed order, accompanied by a subscript indicating the number of atoms of that by a subscript indicating the number of atoms of that element in the moleculeelement in the molecule C8H10N4O2

C3H6N6O6

C4H10OBCl3

Covalent CompoundsCovalent Compounds• Inorganic compoundsInorganic compounds

– – Compounds that consist primarily of elements other than carbon and hydrogenCompounds that consist primarily of elements other than carbon and hydrogen

– – Include both covalent and ionic compoundsInclude both covalent and ionic compounds

– – Formulas are written when the component elements are listed beginning with the one Formulas are written when the component elements are listed beginning with the one farthest to the left in the periodic table with those in the same group listed farthest to the left in the periodic table with those in the same group listed alphabetically alphabetically

• Organic compoundsOrganic compounds– – Covalent compounds that contain predominantly carbon and hydrogenCovalent compounds that contain predominantly carbon and hydrogen

– – Formulas of organic compounds written with carbon first, followed by hydrogen and Formulas of organic compounds written with carbon first, followed by hydrogen and then by other elements in alphabetical orderthen by other elements in alphabetical order

Inorganic Covalent CompoundsInorganic Covalent Compounds• Some pure elements exist as covalent Some pure elements exist as covalent

moleculesmolecules

• Hydrogen, nitrogen, oxygen, and the Hydrogen, nitrogen, oxygen, and the halogens occur as diatomic molecules and halogens occur as diatomic molecules and contain two atomscontain two atoms

• A few pure elements, such as elemental A few pure elements, such as elemental phosphorus and sulfur, are polyatomic phosphorus and sulfur, are polyatomic molecules and contain more than two atomsmolecules and contain more than two atoms

Binary covalent compounds — covalent compounds that contain Binary covalent compounds — covalent compounds that contain only two elements only two elements

The procedure for naming them uses the following steps:The procedure for naming them uses the following steps:

1. Place the elements in their proper order.1. Place the elements in their proper order.a.a. Element farthest to the left in the periodic table is named first. If both elements Element farthest to the left in the periodic table is named first. If both elements

are in the same group, the element closer to the bottom of the column is named are in the same group, the element closer to the bottom of the column is named first.first.

b.b. Second element is named as if it were a monatomic anion in an ionic compound Second element is named as if it were a monatomic anion in an ionic compound with the suffix –with the suffix –ide ide attachedattached to the root of the element nameto the root of the element name

2. 2. Identify the number of each type of atom present.Identify the number of each type of atom present. a. Prefixes derived from Greek stems are used to indicate the number of each type of a. Prefixes derived from Greek stems are used to indicate the number of each type of

atom in the formula unit.atom in the formula unit. b. If the molecule contains more than one atom of both elements, then prefixes are b. If the molecule contains more than one atom of both elements, then prefixes are

used for both. used for both. c. With some names, the final c. With some names, the final aa or or oo of the prefix is dropped to avoid awkward of the prefix is dropped to avoid awkward

pronunciation.pronunciation.

3.3.Write the name of the compound.Write the name of the compound.

a.a.Binary compounds of the elements with oxygen are named as “element oxide” with Binary compounds of the elements with oxygen are named as “element oxide” with prefixes that indicate the number of atoms of each element per formula unit.prefixes that indicate the number of atoms of each element per formula unit.

b. Certain compounds are always called by their common names assigned long ago b. Certain compounds are always called by their common names assigned long ago when names rather than formulas were used.when names rather than formulas were used.

Binary Inorganic CompoundsBinary Inorganic Compounds

Binary Inorganic CompoundsBinary Inorganic Compounds

Organic Covalent compoundsOrganic Covalent compoundsHydrocarbons and Biologically Important Hydrocarbons and Biologically Important

CompoundsCompounds HydrocarbonsHydrocarbons Consist entirely of carbon and hydrogenConsist entirely of carbon and hydrogen Four major classes of hydrocarbons:Four major classes of hydrocarbons:1. Alkanes — contain only carbon-hydrogen and 1. Alkanes — contain only carbon-hydrogen and

carbon-carbon single bondscarbon-carbon single bonds

2. Alkenes — contain at least one carbon-carbon 2. Alkenes — contain at least one carbon-carbon double bonddouble bond

3. Alkynes — contain a least one carbon-carbon 3. Alkynes — contain a least one carbon-carbon triple bondtriple bond

4.4. Aromatics — contain rings of six carbon atoms Aromatics — contain rings of six carbon atoms that can be drawn with alternating single and that can be drawn with alternating single and double bondsdouble bonds Biologically Important Biologically Important

CompoundsCompounds1.1. CarbohydratesCarbohydrates2.2. LipidsLipids3.3. BiopolymersBiopolymers

1.1. ProteinsProteins2.2. Nucleic AcidsNucleic Acids

To Be Covered in Weeks To Be Covered in Weeks 6 and 76 and 7

Coordinate Inorganic CompoundsCoordinate Inorganic Compounds

To Be Covered To Be Covered in Week 8in Week 8

To Be Covered To Be Covered in Weeks 9 and 10in Weeks 9 and 10

Acids and BasesAcids and Bases AcidsAcids

– – A substance with at least one hydrogen atom A substance with at least one hydrogen atom that can dissociate to form an anion and an Hthat can dissociate to form an anion and an H+ +

ion (a proton) in aqueous solution, thereby ion (a proton) in aqueous solution, thereby forming an forming an acidic solutionacidic solution

BasesBases – – Compounds that produce hydroxide ions (OHCompounds that produce hydroxide ions (OH––) )

and a cation when dissolved in water, thus and a cation when dissolved in water, thus forming a forming a basic solutionbasic solution

NeutralNeutral – – Solutions that are neither basic nor acidicSolutions that are neither basic nor acidic

Counting AtomsCounting AtomsChemistry is a quantitative science—Chemistry is a quantitative science—

we need a “counting unit.”we need a “counting unit.”

MOLE - MOLE - 1 mole is the 1 mole is the amount of substance that amount of substance that contains as many particles contains as many particles (atoms, molecules) as there (atoms, molecules) as there are in 12.0 g of 12C.are in 12.0 g of 12C.

518 g of Pb, 2.50 mol

6.02214199 x 106.02214199 x 102323

Avogadro’s Avogadro’s NumberNumber

There is Avogadro’s number of particles in a mole of any substance.

There is Avogadro’s number of particles in a mole of any substance.Amedeo AvogadroAmedeo Avogadro

1776-18561776-1856

Molar MassMolar Mass1 mol of 1 mol of 1212C C

= 12.00 g of C= 12.00 g of C = 6.022 x 10 = 6.022 x 102323 atoms of atoms of CC

12.00 g of 12.00 g of 1212C is its C is its MOLAR MASSMOLAR MASS

Taking into account all of Taking into account all of the isotopes of C, the the isotopes of C, the molar mass of C is molar mass of C is 12.011 g/mol12.011 g/mol

One-mole One-mole AmountsAmounts

Molar massMolar mass• • Flowchart for converting between mass, Flowchart for converting between mass,

number of moles, and number of atoms, number of moles, and number of atoms, molecules, or formula unitsmolecules, or formula units

PROBLEM: What amount of Mg is PROBLEM: What amount of Mg is represented by 0.200 g? How many atoms?represented by 0.200 g? How many atoms?Mg has a molar mass of Mg has a molar mass of

24.3050 g/mol.24.3050 g/mol.

PROBLEM: How many hydrogen atoms in PROBLEM: How many hydrogen atoms in 0.036 moles of propane C0.036 moles of propane C33HH88? In 2.7 ? In 2.7 moles?moles?

Molar massMolar mass

MOLECULAR MASS & MOLAR MOLECULAR MASS & MOLAR MASSMASS

Molecular weightMolecular weight = sum of the atomic = sum of the atomic

weights of all atoms in the molecule.weights of all atoms in the molecule.

Molar massMolar mass = molecular weight in = molecular weight in

gramsgramsProblem: What is the Problem: What is the molar mass of ethanol – molar mass of ethanol – CC22HH66O?O?1 mol contains1 mol contains

2 mol C (12.01 g C/1 mol C/1 mol C2 mol C (12.01 g C/1 mol C/1 mol C22HH66O) = O) =

6 mol H (1.01 g H/1 mol H/1 mol C6 mol H (1.01 g H/1 mol H/1 mol C22HH66O) = O) =

1 mol O (16.00 g O/1 mol O/1 mol C1 mol O (16.00 g O/1 mol O/1 mol C22HH66O) O)

= =

TOTAL = TOTAL = Molar Mass Molar Mass = =

• Formula = Formula =

• Molar mass =Molar mass =

CC88HH99NONO22

TylenolTylenol

• Molecular mass of a substanceMolecular mass of a substance

– – Sum of the average masses of the atoms in one Sum of the average masses of the atoms in one molecule of the substancemolecule of the substance

– – Calculated by summing the atomic masses of the Calculated by summing the atomic masses of the elements in the substance, each multiplied by its elements in the substance, each multiplied by its subscript in the molecular formulasubscript in the molecular formula

– – Units of molecular mass are atomic mass units (amu)Units of molecular mass are atomic mass units (amu)

MOLECULAR MASS & MOLAR MOLECULAR MASS & MOLAR MASSMASS

PROBLEM: PROBLEM: How many How many molesmoles of alcohol are of alcohol are there in a “standard” can of beer if there there in a “standard” can of beer if there are 21.3 g of Care 21.3 g of C22HH66O?O?(a) Molar mass of (a) Molar mass of CC22HH66OO = 46.08 g/mol = 46.08 g/mol

(b) Calc. moles of alcohol(b) Calc. moles of alcohol

Molar MassMolar Mass

PROBLEM: How many PROBLEM: How many moleculesmolecules of alcohol of alcohol are there in a “standard” can of beer if are there in a “standard” can of beer if there are 21.3 g of Cthere are 21.3 g of C22HH66O?O?

Molar MassMolar Mass

(a) 21.3 g of (a) 21.3 g of C2H6O is is 0.462 mol of C2H6O.

(b) Calc. molecules of alcohol(b) Calc. molecules of alcohol

PROBLEM: How many PROBLEM: How many atoms of C atoms of C from ethanol are there in a “standard” can of are there in a “standard” can of beer if there are 21.3 g of Cbeer if there are 21.3 g of C22HH66O?O?

Molar MassMolar Mass

(a) 21.3 g of (a) 21.3 g of C2H6O is is 0.462 mol of C2H6O which is 2.78 E23 .

(b) Calc. Atoms of carbon.(b) Calc. Atoms of carbon.

A pure compound always consists of the same elements combined in the A pure compound always consists of the same elements combined in the same proportions by weight.same proportions by weight.

Therefore, we can express molecular composition as Therefore, we can express molecular composition as PERCENT BY WEIGHTPERCENT BY WEIGHT

Ethanol, C2H6O52.13% C13.15% H 34.72% O

Calculating Mass PercentagesCalculating Mass Percentages

Law of definite proportionsLaw of definite proportions states that a chemical states that a chemical compound always contains the same proportion of compound always contains the same proportion of elements by masselements by mass

Percent composition Percent composition — the percentage of each element — the percentage of each element present in a pure substance—is constantpresent in a pure substance—is constant

Calculation of mass percentageCalculation of mass percentage 1. Use atomic masses to calculate the molar mass of the 1. Use atomic masses to calculate the molar mass of the

compoundcompound 2. Divide the mass of each element by the molar mass of the 2. Divide the mass of each element by the molar mass of the

compound and then multiply by 100% to obtain percentagescompound and then multiply by 100% to obtain percentages 3. To find the mass of an element contained in a given mass 3. To find the mass of an element contained in a given mass

of the compound, multiply the mass of the compound by the of the compound, multiply the mass of the compound by the mass percentage of that element expressed as a decimalmass percentage of that element expressed as a decimal

Percent CompositionPercent CompositionConsider NOConsider NO22, Molar mass = ?, Molar mass = ?

What is the weight percent of N and of O?What is the weight percent of N and of O?

What are the weight percentages of N and What are the weight percentages of N and O in NO?O in NO?

A compound of B and H is 81.10% B. What is its empirical formula?1. Calculate the number of moles of each element in

100.0 g of sample.

3. Now, recognize that atoms combine in the ratio of small whole numbers.

4. Find the ratio of moles of elements in the compound.

2. Take the ratio of moles of B and H. Always divide by the smaller number.

We need to do an EXPERIMENT to find the MOLAR MASS. Experiment gives 53.3 g/mol

Compare with the mass of B2H5 = 26.66 g/unit , i.e. Find the ratio of these masses.

Percent CompositionPercent Composition

Can use the empirical formula of a Can use the empirical formula of a substance to determine its percent substance to determine its percent compositioncomposition

Can use the percent composition of a sample Can use the percent composition of a sample to determine its empirical formula, which to determine its empirical formula, which then can be used to determine the molecular then can be used to determine the molecular formula—a procedure used to determine the formula—a procedure used to determine the empirical and molecular formulas of empirical and molecular formulas of penicillinpenicillin

Determining the Empirical Determining the Empirical Formula of PenicillinFormula of Penicillin

The combustion analysis of Penicillin G C = 53.9%H = 4.8%N = 7.9%S = 6.5%Na = 6.5%Total = 82.1%

Determining the Empirical and Determining the Empirical and Molecular Formulas of PenicillinMolecular Formulas of Penicillin

• A chemical equation is an expression that gives the A chemical equation is an expression that gives the identities and quantities of the substances in a chemical identities and quantities of the substances in a chemical reactionreaction

• Chemical formulas and other symbols are used to indicate Chemical formulas and other symbols are used to indicate the starting material(s) or the starting material(s) or reactant(s),reactant(s), which are written on which are written on the left side of the equation, and the final compound(s) or the left side of the equation, and the final compound(s) or product(s),product(s), which are written on the right side. An arrow, which are written on the right side. An arrow, read as yields or reacts to form, points from the reactants read as yields or reacts to form, points from the reactants to the products.to the products.

• Abbreviations are added in parentheses as subscripts to Abbreviations are added in parentheses as subscripts to indicate the physical state of each species:—(indicate the physical state of each species:—(ss) for solid, () for solid, (ll) ) for liquid, (for liquid, (gg) for gas, and () for gas, and (aqaq) for an ) for an aqueousaqueous solution.solution.

• A balanced chemical equation A balanced chemical equation is when both the numbers of is when both the numbers of each type of atom and the total charge are the same on each type of atom and the total charge are the same on both sides. A chemical reaction represents a change in the both sides. A chemical reaction represents a change in the distribution of atoms but not in the number of atoms.distribution of atoms but not in the number of atoms.

Chemical EquationsChemical Equations

Chemical EquationsChemical Equations

• Look at the information an equation Look at the information an equation provides:provides:

(g)2(s)(g)3(s)2 CO 3 + Fe 2 CO 3 + OFe

• Balanced chemical equationBalanced chemical equation – – Provides qualitative information about the Provides qualitative information about the

identities and identities and physical states of physical states of the reactants and productsthe reactants and products

– – Provides quantitative information because it Provides quantitative information because it tells the relative tells the relative amounts of reactants and amounts of reactants and products consumed or products consumed or produced produced in the reactionin the reaction

– – The number of atoms, molecules, or formula The number of atoms, molecules, or formula units of a reactant units of a reactant or product in a balanced or product in a balanced chemical equation is the chemical equation is the coefficient of that speciescoefficient of that species

– – Mole ratio of two substances in a chemical Mole ratio of two substances in a chemical reaction is the ratio reaction is the ratio of their of their coefficients in the balanced chemical equationcoefficients in the balanced chemical equation

Balancing Simple Chemical EquationsBalancing Simple Chemical Equations Method for balancing chemical equationsMethod for balancing chemical equations

1.1.Identify the most complex substance.Identify the most complex substance.2.2.Beginning with that substance, choose an element that Beginning with that substance, choose an element that

appears in only one reactant and one product. Adjust the appears in only one reactant and one product. Adjust the coefficients to obtain the same number of atoms of this coefficients to obtain the same number of atoms of this element on both sides.element on both sides.

Optionally - Balance polyatomic ions (if present) Optionally - Balance polyatomic ions (if present) as a unit.as a unit.

Balance the remaining atoms, usually ending with the Balance the remaining atoms, usually ending with the least-complex substance and using fractional coefficients if least-complex substance and using fractional coefficients if necessary. If a fractional coefficient is used, multiply both necessary. If a fractional coefficient is used, multiply both sides of the equation by the denominator to obtain whole sides of the equation by the denominator to obtain whole numbers for the coefficients.numbers for the coefficients.

Count the numbers of atoms of each kind on both sides of Count the numbers of atoms of each kind on both sides of the equation to be sure that the chemical equation is the equation to be sure that the chemical equation is balanced.balanced.

Chemical EquationsChemical Equations• Law of Conservation of Matter Law of Conservation of Matter

– There is no detectable change in quantity of There is no detectable change in quantity of matter in an ordinary chemical reaction.matter in an ordinary chemical reaction.

– Balanced chemical equations must always Balanced chemical equations must always include the same number of each kind of include the same number of each kind of atom on both sides of the equation.atom on both sides of the equation.

– This law was determined by Antoine This law was determined by Antoine Lavoisier.Lavoisier.

• Propane,CPropane,C33HH88, burns in oxygen to give , burns in oxygen to give carbon dioxide and water.carbon dioxide and water.

OH 4 CO 3 O 5 HC 22283

Law of Conservation of MatterLaw of Conservation of Matter

• NHNH33 burns in oxygen to form NO & burns in oxygen to form NO & waterwater

Law of Conservation of MatterLaw of Conservation of Matter•CC77HH1616 burns in oxygen to form carbon burns in oxygen to form carbon dioxide and water.dioxide and water.

KClOKClO33 + C + C1212HH2222OO1111 KCl + CO KCl + CO22 + H + H22OO

Balance this reactionBalance this reaction

CaSOCaSO44 + CH + CH44 + CO + CO22 CaCO CaCO3 3 + S + H+ S + H22OO

Balance this reactionBalance this reaction

Mass Relationships in Chemical Mass Relationships in Chemical EquationsEquations

• A balanced chemical equation gives the A balanced chemical equation gives the identity of the reactants and products and the identity of the reactants and products and the accurate number of molecules or moles of accurate number of molecules or moles of each that are consumed or produced.each that are consumed or produced.

• Stoichiometry Stoichiometry is a collective term for the is a collective term for the quantitative relationships between the quantitative relationships between the masses, numbers of moles, and numbers of masses, numbers of moles, and numbers of particles (atoms, molecules, and ions) of the particles (atoms, molecules, and ions) of the reactants and products in a balanced reaction.reactants and products in a balanced reaction.

• A stoichiometric quantity is the amount of A stoichiometric quantity is the amount of product or reactant specified by the product or reactant specified by the coefficients in a balanced chemical equation.coefficients in a balanced chemical equation.

Stoichiometry ProblemsStoichiometry Problems

• Steps in converting between masses of Steps in converting between masses of reactants and productreactants and product

1.1.Convert the mass of one substance (Substance A) to Convert the mass of one substance (Substance A) to the corresponding number of moles using its molar the corresponding number of moles using its molar mass.mass.

2.2.From the balanced chemical equation, obtain the From the balanced chemical equation, obtain the number of moles of another substance (B) from the number of moles of another substance (B) from the number of moles of substance A using the number of moles of substance A using the appropriate mole ratio (the ratio of their appropriate mole ratio (the ratio of their coefficients).coefficients).

3.3.Convert the number of moles of substance B to mass Convert the number of moles of substance B to mass using using its molar mass.its molar mass.

• • Converting amounts of substances to moles, Converting amounts of substances to moles, and vice versa, is the key to all stoichiometry and vice versa, is the key to all stoichiometry problems.problems.

Calculations Based on Chemical Calculations Based on Chemical EquationsEquations

• How many CO molecules are required to How many CO molecules are required to react with 25 MOLES of Fereact with 25 MOLES of Fe22OO33??

Calculations Based on Chemical Calculations Based on Chemical EquationsEquations

• How many iron atoms can be produced by How many iron atoms can be produced by the reaction of 2.50the reaction of 2.50EE5 MOLES of iron (III) 5 MOLES of iron (III) oxide with excess carbon monoxide?oxide with excess carbon monoxide?

Calculations Based on Chemical Calculations Based on Chemical EquationsEquations

• What mass of CO is required to react with What mass of CO is required to react with 146 g of iron (III) oxide?146 g of iron (III) oxide?

Limiting ReactantsLimiting Reactants• If one or more of the reactants is not used If one or more of the reactants is not used

up completely but is left over when the up completely but is left over when the reaction is completed, then the amount of reaction is completed, then the amount of product that can be obtained is limited by product that can be obtained is limited by the amount of only one of the reactantsthe amount of only one of the reactants

• A limiting reactant is the reactant that A limiting reactant is the reactant that restricts the amount of product obtained. restricts the amount of product obtained. The reactant that remains after a reaction The reactant that remains after a reaction has gone to completion is present in has gone to completion is present in excessexcess..

Limiting Reactant ConceptLimiting Reactant Concept• What is the maximum mass of sulfur dioxide What is the maximum mass of sulfur dioxide

that can be produced by the reaction of 95.6 that can be produced by the reaction of 95.6 g of carbon disulfide with 110. g of oxygen?g of carbon disulfide with 110. g of oxygen?

2222 SO 2 CO O 3 CS

Limiting Reactant ConceptLimiting Reactant Concept• What is the maximum mass of sulfur dioxide What is the maximum mass of sulfur dioxide

that can be produced by the reaction of 95.6 that can be produced by the reaction of 95.6 g of carbon disulfide with 110. g of oxygen?g of carbon disulfide with 110. g of oxygen?

Percent Yields from ReactionsPercent Yields from Reactions• The The Limiting Reactant Limiting Reactant determines the maximum determines the maximum

amount of product that can be formed from the amount of product that can be formed from the reactants when reactants are not present in reactants when reactants are not present in stoichiometric quantities.stoichiometric quantities.

• The The Theoretical Yield Theoretical Yield is calculated by assuming that the is calculated by assuming that the reaction goes to completion.reaction goes to completion.– Determined from the limiting reactant calculation.Determined from the limiting reactant calculation.

• Actual Yield Actual Yield is the amount of a specified pure product is the amount of a specified pure product made in a given reaction.made in a given reaction.– In the laboratory, this is the amount of product that In the laboratory, this is the amount of product that

is formed in your beaker, after it is purified and dried.is formed in your beaker, after it is purified and dried.• Percent YieldPercent Yield indicates how much of the product is indicates how much of the product is

obtained from a reaction.obtained from a reaction.

% yield = actual yield

theoretical yield100%

Percent Yields from ReactionsPercent Yields from Reactions• A 10.0 g sample of ethanol, CA 10.0 g sample of ethanol, C22HH55OH, was boiled with OH, was boiled with

excess acetic acid, CHexcess acetic acid, CH33COOH, to produce 14.8 g of COOH, to produce 14.8 g of ethyl acetate, CHethyl acetate, CH33COOCCOOC22HH55. . What is the percent yield?What is the percent yield?

Classifying Chemical ReactionsClassifying Chemical Reactions

Most chemical reactions can be Most chemical reactions can be classified into one or more of only classified into one or more of only four basic types:four basic types: 1. 1. Acid-base reactionsAcid-base reactions acid + base acid + base salt salt 2. 2. Exchange reactionsExchange reactions (Single Displacement, Double (Single Displacement, Double

Displacement, Metathesis)Displacement, Metathesis) AB + C AB + C AC + B AC + B oror AB + CD AB + CD AD + CB AD + CB 3. 3. Condensation reactionCondensation reactions (and the reverse,s (and the reverse, cleavage cleavage

reactionsreactions) (Combination, Decomposition)) (Combination, Decomposition) Condensation: A + B Condensation: A + B AB AB

Cleavage: AB Cleavage: AB A + B A + B 4. 4. Oxidation-reduction reactions Oxidation-reduction reactions oxidant + reductant oxidant + reductant reduced oxidant + reduced oxidant +

oxidized reductant oxidized reductant

To Be Covered To Be Covered in Week 9in Week 9