Countertop Chemistry

The Science HouseNorth Carolina State University

The Science HouseBox 8211 Raleigh, NC 27695www.science-house.org

2005 Edition

Table of Contents

Introduction ........................................................................................ ii

Experiments

1. Dancing Spaghetti ................................................................................ 12. Combustion .......................................................................................... 33. Law of Conservation of Matter .............................................................. 6 4. Chromatography of Foods .................................................................... 105. Ziploc Bag Chemistry ........................................................................... 146. Floating Candles ................................................................................... 187. Production of Oxygen ............................................................................ 218. Production of Hydrogen ......................................................................... 239. Production of Carbon Dioxide ................................................................ 2510.Single Replacement Reactions .............................................................. 2711.Double Replacement Reactions ............................................................. 3012.Gas Producing Reactions ....................................................................... 3313.Red, White and Blue ............................................................................... 3614.Rate of Solution ...................................................................................... 3815. Ice Cream ............................................................................................... 4216.Daffy Densities ....................................................................................... 4517.Red, White and Blue II ........................................................................... 4718.Oobleck .................................................................................................. 4919.Gluep ...................................................................................................... 5120.Clear Slime Polymer ............................................................................... 5321.The Cat's Meow ...................................................................................... 5522.Cabbage Juice Indicator ......................................................................... 5723. Invisible Ink ............................................................................................. 6024.The Witches' Potion ................................................................................ 6225.What's in a Penny? ................................................................................. 6526.Formulas Poker ....................................................................................... 6827.Radioactive Decay of Candium ............................................................... 72

Appendix ........................................................................................................... 75

Introduction to Countertop Chemistry

There is a lot of interesting science to investigate in this world. Not all science is done by men wearing white coats and working in laboratories. All of the world around us involves science. A child or teacher can investigate some pretty interesting stuff without requiring a laboratory or expensive laboratory equipment or dangerous chemicals.

These activities came from teacher training workshops that have been offered by The Science House since 1992. Many teachers have taken the workshops and have applied the activities in their own classrooms – from first grade to high school.

We believe that students should be involved in active learning in which the teacher acts as a guide, not an answer machine. However, to be a good guide, the teacher has to have the road map in her/his head. So these activities include directions for doing the activities, suggestions on finding materials, and a little background on the science involved.

We realize that there are no new science demonstrations under the sun. Many of these may be experiments that you have seen before in another format. The point of this book is to assemble them in a rational format that encourages you, as a student or teacher, to try them out. A science demonstration in a book is useless until someone actually does it and uses the experience to help her/his understanding.

The Science House is a science and mathematics learning outreach program of the College of Physical and Mathematical Sciences at North Carolina State University. The mission of The Science House is to work in partnership with K-12 teachers to emphasize the use of hands-on learning activities in mathematics and science classes. The Science House provides a variety of in-service training and enrichment activities that reach students and teachers across North Carolina.

We are located on the Centennial Campus at North Carolina State University in Raleigh, NC. For more information on our programs, please visit our website at www.science-house.org, write to The Science House at Box 8211, NCSU, Raleigh, NC 27695-8211, or email us at Science_House@ncsu.edu.

Fair Use Statement:

We make these materials available to teachers and students to encourage hands-on learning in science. Teachers may freely reproduce these materials in hard copy as long as the footer "The Science House, NC State University," is indicated.

Safety Statement:

Countertop Chemistry The Science House, NC State University ii

North Carolina State University and The Science House makes no warranty, explicit or implied, as to the safety or suitability of these activities. We urge you to always use proper safety equipment and precautions.

Acknowledgments

These activities are the results of contributions from a number of people. Melissa Cole Brown wrote the first draft of the Countertop Chemistry activities. For this new, 2003 edition, Dr. Alton Banks and Dr. Catherine Banks have carried out a complete revision and update of the activities. After teaching these workshops many times and being the recipients of many helpful hints, we gratefully acknowledge the contributions of Rebecca King, Mike Smith, Dr. Alton Banks, Dr. George Wahl, Todd Boyette, Bonnie Barnes Bordeaux and Scott Ragan. We gratefully acknowledge the permission from Dr. Andy Sae to allow us to adapt laboratories from “Chemical Magic From the Grocery Store.”

Countertop Chemistry The Science House, NC State University iii

Activities and Demonstrations

There are many ways to use these experiments. The students should do most of these experiments so that they can see the phenomena "up close and personal" and try out variations for themselves. Many of the activities are simple and cheap enough for the students to bring home and show their parents. Educating parents is just as important as teaching students!

You may wish to use some of the activities as demonstrations in which you do only one setup of the activity and show it to the class. Be sure to make your demonstrations interactive! Education research indicates that the presentation of information plays a vital role in students’ acquisition of knowledge. Here are some tips about how to make demonstrations more meaningful to your students:

Use students as helpers. If an activity requires Chemical A to be poured into Beaker B, let Child C do the pouring, not the teacher.

Begin demonstrations by asking questions and by linking the demonstrations to the related subject matter. This book has many questions for you to ask your students or yourself.

During demonstrations, continue to ask questions to the students or allow them to discuss the demonstrations with their classmates. ("What did you see?"; "What do you think will happen if we do...?"; "Turn to your neighbor and explain what you just heard").

At the end of demonstrations, ask each student to write a three-sentence explanation of what happened in the experiment and what they learned from it. Reading these explanations after class will help you to better learn how to improve your use of demonstrations and hands-on learning activities.

Each of the Countertop Chemistry activities can be used at a variety of grade levels. Different grade students will learn different things from the activities. Therefore, some of the questions included may be quite appropriate for first grade, whereas others may be better suited for twelfth grade. Each activity includes directions, questions, materials lists, and tips for carrying out the activity.

In conclusion, there are two simple rules that we have learned about doing demonstrations or activities with students:

If it stinks, it is chemistry. If it is slimy, it is biology. If it does not work, it is physics.

If a demonstration works the first time, do not repeat it. If a demonstration does not work the first time in front of your students, repeat it only once. Then give up.

Have fun!

Countertop Chemistry The Science House, NC State University iv

Experiment #1

Dancing SpaghettiIf you have ever cooked a spaghetti dinner, you may have noticed that spaghetti noodles sink when placed into water. This process happens because the noodles are more dense than the water. This lab investigates why that principle does not work with other solutions.

Materials Substitutions 1- 1000 mL beaker 1 glass mixing bowl or vase 10 g sodium hydrogencarbonate 3 tsp. baking soda 45 mL 3% acetic acid 4-5 tbsp. vinegar 10-2 cm pieces of vermicelli Water

Procedure1. Fill your clear container 3/4 full with water. Add the sodium

hydrogencarbonate (or baking soda) and stir to dissolve.

2. Break the vermicelli into 2-cm (one inch) pieces and add them to the container.

3. Add the acetic acid (vinegar). If the vermicelli does not begin to "dance" after a few minutes, more sodium hydrogencarbonate and acetic acid should be added.

*Raisins or mothballs can be used with similar results!

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Experiment #1

Teacher's Notes 1. Vinegar (HC2H3O2) is a 5% solution of acetic acid. It reacts

with baking soda (sodium hydrogencarbonate-NaHCO3), to produce carbon dioxide gas (CO2) and sodium acetate (NaC2H3O2 ). The reaction can be written as follows:

NaHCO3 (aq) + HC2H3O2 (aq) ------> CO2 (g) + H2O (l) + NaC2H3O2 (aq)

2. Bubbles of carbon dioxide gas adhere to the surface of the spaghetti. The result is that the density of the spaghetti plus the gas is less than that of the water solution so the pieces rise to the surface. Many of the bubbles are released at the surface, and the density of the spaghetti is once again greater than that of the solution so the spaghetti sinks.

Children’s "water-wings" operate on the same principle by increasing the volume of the child without increasing the mass considerably.

3. Amounts of baking soda and vinegar are approximate and depend on the type of container used. If a larger container is used, increase the amount of baking soda and vinegar appropriately.

Extensions1. Raisins or mothballs may be used in addition to, or in place of,

the spaghetti.

2. Add a drop of food coloring to your water to enhance the visibility of the "dance" movement.

DisposalSolids may be placed in the trash and solutions may be poured in

thesink.

Countertop Chemistry The Science House, NC State University 2

Experiment #2

CombustionThis lab demonstrates why an object weighs more after combustion occurs rather than before it occurs.

Materials Substitutions Aluminum pie pan Balance Uncoated extra-coarse steel wool Regular steel wool Bunsen burner LPG burner Crucible tongs Kitchen tongs

Safety PrecautionsFor your own safety wait until your teacher tells you its ok before you light the burner. Turn on the gas only after the match has been lighted. This will prevent an excess amount of gas from building up around the burner. The heated steel wool will be very hot and tongs must be used when handling it. If the pie pan becomes hot, it should not be put on the balance until it cools.

Procedure1. Weigh the empty pie pan, and record the mass in the Data section.

2. Place a pad of the steel wool (approximately 3 in. x 3 in.) in the pan and record the weight of the pan and pad.

3. Light the burner and adjust it to obtain a blue (hot) flame.

4. Hold the steel wool with the tongs and place it in the flame for several minutes. Rotate the pad so that all parts are exposed to the flame. After all of the pad has a dull gray appearance, turn off the burner. Place the steel wool in the pie pan, sweeping any "popped" pieces of the steel wool into the pie pan.

5. Weigh the pan and steel wool, and record the mass.

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Experiment #2

Data and Observations1. Weight of the empty pan: __________g

2. Weight of the pan and steel wool before heating: __________g

3. Initial weight of the steel wool (#2 - #1): __________g

4. Weight of the pan and steel wool after heating: ___________g

5. Weight of the steel wool after heating (#4 - #1): __________g

6. Difference between the weights of the steel wool before and after heating (#5 - #3): __________g

Questions1. What kind of change took place? 2. Why did the mass of the steel wool change as a result of

heating? Can you explain the differences in the masses? 3. Write a balanced chemical equation for the burning of steel.

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Experiment #2

ExtensionTry burning another metal, like magnesium or aluminum. You may need to include the weight of the tongs (initial and final) in this experiment as some of the oxide will be left on the tongs.

CAUTION: When magnesium burns, it gives off a very bright light. Don't look directly at the light! Permanent eye damage may occur!

Write a balanced chemical equation for the burning of the metal. How are the equations for the burning of steel wool and magnesium (or aluminum) similar? How can the oxidation of a metal (sometimes called corrosion) be prevented?

Teacher's NotesThere is a gain in weight or mass when steel wool is burned. The increase is due to the oxygen that combines with the iron. The balanced chemical equation for the combustion or oxidation of iron is:

4 Fe (s) + 3 O2 (g) --------> 2 Fe2O3 (s)

The corrosion of iron is prevented by not allowing the metallic object to be in contact with oxygen. This can be accomplished by either painting, coating with oil, or galvanizing the steel objects. Corrosion weakens the iron because the iron oxide (rust) flakes off and therefore reducing the amount of the steel. It is best to use coarse to medium coarse steel wool. Fine steel wool will give the effect of a "sparkler"--popping all over the lab bench and possibly onto paper!!! Move papers and towels away from the burner while heating

Students must use a sufficient amount of steel wool to notice a change after heating. Caution students to prepare for some popping of the steel filaments during the experiment. The difference in mass will be very small. An aluminum pie pan under the burner can be used to collect the mass that has "popped".

Disposal Used steel wools pads and pie pans may be placed in the trash can.

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Experiment #3

Law of Conservation of MatterThis experiment will explore whether matter is created or destroyed during a chemical reaction.

Materials Substitutions

Balance 4 graduated cylinders 4 (2 oz.) plastic cups 3-150 mL beakers 3 (5 oz.) plastic cups 0.1M solutions of: NaOH Drano and ammonia solutions

CuSO4 Bluestone algaecide and washing NH3 (aq) sodaNa2CO3

Procedure1. Label the four graduated cylinders (or 2 oz. cups) to contain the

solutions (one each for NaOH, CuSO4, NH3 (aq), and Na2CO3).

2. Use a graduated cylinder to measure about 60 mL (2 oz.) of the NaOH solution. Use a second graduated cylinder to measure about 60 mL (2 oz.) of the CuSO4 solution and pour it into a 150 mL beaker (or 5 oz. cup).

3. Carefully place the two containers on the balance. Weigh the solutions and their containers together and record their combined weight in the Data section.

4. Pour the NaOH solution into the container with the CuSO4 solution. Allow the solutions to mix. Describe what happens in the Data section.

5. Weigh both containers and the mixture again. Record the new weight. Did the weight change?

6. Repeat the process in steps 2 and 3 above, first substituting NH3 (aq.) for the NaOH solution, then substituting Na2CO3 for the NaOH solution. In each case measure and record the masses as described in steps 3 and 5 above.

Data and Observations

Countertop Chemistry The Science House, NC State University 6

Total Weight Before (g) After (g)NaOH and CuSO4

NH3 (aq) and CuSO4

Na2CO3 and CuSO4

Experiment #3

Observation of mixture:

Complete the following equations:1. NaOH + CuSO4 ----> _________________________________2. NH3 (aq) + CuSO4 ----> _______________________________3. Na2CO3 + CuSO4 ----> ________________________________

Questions1. What is the insoluble solid that is produced? Use a solubility

chart to predict the identity of the insoluble product.2. Use the periodic table to prove that total formula mass is conserved. Why is it important to balance a chemical reaction?

ExtensionsThe substances chosen for this lab are common and easy to find. You may want to repeat this lab with solutions of:

Note that NEITHER iron(II) or zinc carbonates or hydroxides are as insoluble as the copper(II) analog. While Barium and lead salts have frequently been used in this type experiment, the

Countertop Chemistry The Science House, NC State University 7

Experiment #3

problems associated with disposing of these materials suggest NOT USING either of these salts in experiments.

Teacher's NotesThis experiment verifies the Law of Conservation of Matter:

Matter is neither created or destroyed as a result of chemical changes,

but may be changed in form.

The balanced equations are as follows: 2NaOH (aq) + CuSO4 (aq) -----> Na2SO4 (aq) + Cu(OH)2

(s) 4NH3 (aq)) + CuSO4 (aq) -------> Cu(NH3)4SO4 (s) Na2CO3 (aq) + CuSO4 (aq) -------> Na2SO4 (aq) + CuCO3

(s)

The insoluble product that is formed is called a precipitate. Solubility Tables can help students predict which product will be insoluble (form a precipitate).

For additional ideas on this concept, see Experiment #2 and the Teacher's Notes.

Solution PreparationThe sodium hydroxide can be obtained from Drano™ or Red Devil™ Lye. If you use Drano, the solution does not need to be very concentrated but you should filter the aluminum filings that are mixed in with the pellets of NaOH. Lye is CAUSTIC so wear gloves and wash all surfaces anyone might touch.

Copper (II) sulfate can be purchased at a good hardware or swimming pool supply store as an algaecide (Bluestone) or root eater. Aqueous ammonia (formerly called ammonium hydroxide) is nothing more than household ammonia, and can be used straight out of the bottle from the grocery store.

Finally, the sodium carbonate can be purchased at the grocery store as washing soda (Arm and Hammer brand) and can be mixed with water to form a solution.

0.1 M solutions can be prepared by dissolving the following masses of solid into enough water to make 1-L of solution:

Countertop Chemistry The Science House, NC State University 8

Experiment #3

Copper sulfate Sodium hydroxideSodium carbonate25g 4 g 10.6 g

Safety PrecautionsAs mentioned in the solutions preparations section, sodium hydroxide is CAUSTIC and should be handled carefully. Students may need to wear gloves. The base will feel slippery on the skin and should be washed immediately. Copper solutions can cause eye infections, so students should wash their hands after handling these substances, too.

DisposalAll solids should be placed in trash cans. Most solutions can be poured down the sink. Check your local municipal water regulations concerning copper sulfate, as some water regulators restrict the concentration of copper (II) ions that can be poured down drains.

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Experiment #4

Chromatography of FoodsChromatography is a separation technique for mixtures based upon their relative affinities for stationary and mobile phases. This technique will be practiced by separating a mixture of FD&C dyes.

Materials Large coffee filters (15 cm) Toothpicks Jar lid (4 cm) Petri dishes Food coloring sets - 4 vials

Grape & Orange Kool-Aid 1 lb. bag of M&M's Transparency pens Pencil with graphite-based

led

Procedure1. On a piece of filter paper, use a pencil to trace a circle with the lid.

.

2. Use a pencil to number the spots on the filter paper for each of the substances to be tested. Your teacher will tell you how many positions you will need. Spread out the numbers so they are equal distances apart.

3. Record the substances to be tested by their appropriate number in the Data section.

4. For each of the substances to be tested place a small dot on the penciled line by dipping a toothpick into the colored liquid to be tested and touching the paper. Allow the spot to dry and then re-spot in the same position. (For the solids to be tested use the directions found in the Teacher’s Notes to prepare the samples.)

5. Use the pencil to punch a hole in the center of the coffee filter. Insert a folded piece of coffee filter into the hole as a wick.

Countertop Chemistry The Science House, NC State University 10

Hole for wick

Pencilled circle

Locations for substances to be testedspaced equally around circle

Filter paper (or coffee filter)

12

34

wick

Side ViewTop View

Experiment #4

6. Add water to the Petri dish so that it is approximately one-third full. Set the wick into the water with the filter paper resting on top of the disk. Allow the chromatogram to develop. The filter paper itself must NOT touch the water in the Petri dish.

7. For best separation of components, remove the chromatogram BEFORE the water reaches the edge of the filter paper (chromatograph). Record the colors in the data table. What trends do you note? (Are there primary colors in more than one sample?)

Data and ObservationsSubstance Center Middle Edge

Tape your chromatogram on the back of this sheet.

Questions1. What kind of change took place? Was it chemical or physical?

How can you tell if the change was chemical or physical? What could you do to test this hypothesis?

2. Why do we use chromatography? 3. How might a chemist use a similar process to analyze a sample?4. What do the words heterogeneous and homogeneous mean?

How do they apply to the substances in this lab?5. What are two other mixtures that can be separated by ordinary

physical means?

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Experiment #4

Teacher's NotesDirections for preparation of test substances:

1. CHARTREUSE- 12 drops yellow food coloring & 1 drop green food coloring. Mix and apply to the paper strip with a toothpick.

2. TURQUOISE- 5 drops blue food coloring & 1 drop green food coloring.

3. M&M's- Place one drop of water on one M&M and use the toothpick to apply the coloring from that drop of water. Use a brown or tan M&M then repeat process for a green M&M.

4. PURPLE SAURUS REX- Mix an entire packet of unsweetened Kool-Aid with a few drops of water to make a thick paste. Apply to the paper strips with a toothpick.

5. ORANGE KOOL-AID- Mix an entire pack of unsweetened Orange Kool-Aid with a few drops of water to make a paste. Apply to the chromatogram with a toothpick.

Recommended pens to use for this lab are: Vis-à-Vis™ transparency pens (black, blue, red, green) or Flair™ black pens.

Results of Chromatographs:

Coloring Center Middle EdgeChartreuse Blue YellowTurquoiseBrown M&M Yellow RedGreen M&M Blue YellowPurple Kool-Aid Blue RedOrange Kool-Aid Yellow Red

Answers to questions:

1. Chromatography is a physical change. Any of the separated colors could simply be remixed in water. Physical changes are reversible.

Experiment #4

2. Chromatography is a method of separation for pigments or dyes by using different rates of evaporation for the component substances.

3. Chemists can use more complex forms of this method to analyze a sample to determine its contents.

4. Homogeneous matter is the same throughout and exists in only one phase of matter. Heterogeneous matter is composed of a mixture of substances that can usually be seen with the naked eye. Heterogeneous matter can be separated by physical changes.

5. Sand and salt can be separated by dissolving the salt in water and filtering the sand from the solution. Evaporation of the water would recover the salt. COLORED M&M'S can be separated by moving the differently colored pieces into separate piles.

Student Answers Will Vary

Safety PrecautionsYou should monitor the eating of the M&M's to be sure that the students are not consuming the ones used for the experiment or ones that have been handled in any way. You might divide the candies by pouring some into a small bathroom paper cup and pass them out to the students.

DisposalAll liquid materials may be poured down the sink. All sold materials

should be placed in a trash can.

Experiment #5

Ziploc™ Bag ChemistryThree reactions are performed in a sealed Ziploc™ bag so that the reactions can be easily observed.

Materials (per lab group) Substitutions 4 Ziploc™ bags 1 tbsp. calcium chloride 30 mL water 2 tbsp. sodium hydrogencarbonate Baking soda 35mm film canister (top optional) Small paper cup 30 mL Indicator solution (phenol red) 30 mL red cabbage juice

Procedure1. Add 2 tbsp. sodium hydrogencarbonate to a Ziploc bag. Gently

place a film canister (approximately 1/3 full of water) inside the bag in the upright position. Squeeze out any excess air and seal the bag. Spill the water into the bag by shaking. Look, listen, and feel. Record your observations in the Data section.

2. Add 1 tbsp. of calcium chloride to a second Ziploc bag. Repeat the remaining steps of step 1 for the calcium chloride and record your observations for this material.

3. Mix 2 tbsp. of sodium bicarbonate and 1 tbsp. of calcium chloride in a third Ziploc bag and mix thoroughly. Gently place a film canister (approximately 1/3 full of water) inside the bag in the upright position. Again, remove the excess air and seal the bag. Spill the water in the canister by shaking the bag. Look, listen, and feel!! Record your observations in the Data section.

4. Repeat step 3, replacing the water in the film canister with 30 mL of indicator solution.

Experiment #5

Data and Observations1. Sodium hydrogencarbonate in water: ______________________

_______________________________________________2. Calcium chloride in water: ____________________________

_______________________________________________3. NaHCO3 + CaCl2 in water: ____________________________

_______________________________________________ 4. NaHCO3 + CaCl2 with indicator solution: ___________________

_______________________________________________

Questions1. Classify each of these changes as chemical or physical. Use your

observations to help you make your decisions.2. In the fourth bag, what did the indicator tell you about the

observed reaction?

3.What gas is being produced? How could you test this?4.Write an equation for any chemical changes that have taken

place.5.Define heat of solution.

Experiment #5

Teacher's Notes1. a) There is a physical change in the first bag. See number 5 below for explanation b) A physical change occurs in the second bag. c) In the third and fourth bags a chemical change occurs. See note 4 for the equation.

2. Phenol red can be used to show the presence of an acidic solution. It can be purchased at a swimming pool supply store. Many foods also contain indicators. One of these is red cabbage juice.

3. The indicator should show that the reaction occurring in the third bag is acidic. Cabbage juice will turn from red to blue in color, while phenol red will turn from red to yellow.

4. The gas that is produced is carbon dioxide (CO2). It is formed from the carbonate ion, HCO3-. A burning splint would show that the gas extinguishes the flame. Some fire extinguishers use carbon dioxide for this reason.

5. The chemical changes that occur in bags 3 and 4 can be represented by the following equation:

2NaHCO3 (aq) + CaCl2 (aq)-> CaCO3 (aq) + 2NaCl (aq) + H2O (l) + CO2 (g)

6. A physical or chemical change may be accompanied by a change of energy. If the change requires heat from the environment, it is said to be endothermic.

Solute + Solvent + HEAT ---> Solution

7. If it releases energy to the environment, it is said to be exothermic.

Solute + Solvent ----> Solution + HEAT

Experiment #5

Safety PrecautionsAs the Ziploc bags expand, care should be used to prevent excessive pressure build-up. The bags may burst. When calcium chloride is dissolved in water heat is given off, so care must be used with these solutions.

DisposalSolid wastes may be placed in the trash can. All solutions may be poured down the drain, followed by water.

Experiment #6

Floating CandlesStudents will observe a combustion reaction and deduce the components necessary for the reaction to occur. Students will also observe the pressure/volume/# mol relationship for gasses.

Materials Substitutions Water Matches Votive candle Candle taper 2- 400 mL beakers 2 -Small jars Beaker with water Jar with water Large Petri dish Aluminum pie plate

Procedure1. Place a votive candle in the center of an aluminum pie pan and

light it.

2. Carefully pour some water (food coloring optional) into the pie pan until the candle is floating in the water.

3. QUICKLY place the inverted jar over the candle and allow it to rest on the bottom of the pie pan. Report the result in the Data section.

4. Light the votive candle again and repeat steps 1-3. Make sure you dry the inverted jar every time you repeat this step.

5. List the sequence of events and the reason for each result in the Data section. (Repeat steps 1-3 as desired.)

Data and ObservationsSequence the events you observed:

1.

2.

3.

4.

5.

Experiment #6

QuestionsUse your knowledge of the gas laws and the principles of combustion to explain the observations listed above.

Experiment #6

Teacher's Notes1. The correct sequence of events would be:

a) The volume of gas in the jar will expand.b) Some condensation may form on the glassc) The candle will go out.d) The water level will rise as the hot gasses cool.

2. The explanation of the events is:a) As the candle burns, the gas above it is heated and

therefore expands.b) This behavior is known as Charles’ s Law.c) Condensation is a product of the combustion reaction, and

can be formed when the warm moist gas comes in contact with the cool glass surface.

d) Combustion reactions require the presence of oxygen. When the candle has reacted with all of the available oxygen, the candle will go out. After the reaction has ceased, the heat from the combustion is no longer produced. Therefore the gas cools and contracts. The water then returns to the jar. This behavior is stated in the gas law known as Boyle’s Law.

3. Students must use dry candles and glassware to be successful. You may want to have towels and extra candles on hand.

4. When this experiment is performed as a demo, (with a glass pie pan) the jar will rattle at first. This gives evidence that expanded hot air is escaping in the jar.

DisposalAll solid materials may be placed in the trash can and the liquids may be poured in the sink.

Experiment #7

Production of OxygenThis experiment allows the student to generate oxygen gas and to test some of its properties.

Materials Substitutions 3% hydrogen peroxide (H2O2) Yeast 125 mL Erlenmeyer flask small jar Stopper lid Wood splints

toothpicks Candle and matches Teaspoon

Procedure1. Pour approximately 100 mL of 3% hydrogen peroxide into the

flask.

2. Light the candle in preparation of studying the gas.

3. Add 2 tsp. of yeast to the H2O2 and cover loosely with the lid. Bubbles of gas should begin to form.

4. Light a splint and allow it to burn for a few seconds. Extinguish the flame so that the splint is glowing.

5. Immediately, remove the lid and insert the glowing splint into the neck of the jar. Note the result. Replace the lid and collect more gas.

6. Repeat step 4 to retest the gas.

Questions1. Write the equation for the reaction that occurs in the above

experiment.2. What happened when the glowing splint was placed near the

opening of the glass jar?3. Why must the container be closed during the experiment?4. What chemical property of oxygen gas does this experiment

demonstrate?5. List any precautions that should be used if high concentrations of

oxygen are present (ex. oxygen for hospital patients).

Experiment #7

Teacher's NotesIn 1774 Joseph Priestly first prepared oxygen. This was accomplished by focusing sunrays on mercury(II) oxide, producing liquid mercury and a gas. Priestly discovered that the gas made a candle burn more brightly. Lavoisier determined the role oxygen plays in combustion and respiration. Nearly all commercial oxygen is obtained from separation of air. This method is chosen because of the abundance of starting material and the ease isolation of the pure oxygen. In this experiment oxygen is produced from the decomposition of hydrogen peroxide into oxygen and water.

YOUR HYDROGEN PEROXIDE MUST BE FRESH. H2O2 loses oxygen when it is exposed to heat or light. Liver can also be used as a catalyst for an interesting twist. When peroxide is used to sterilize a wound, the peroxide decomposes to release oxygen. Both enzymes in the liver and in the metal ions are catalysis of this reaction.

1. Yeast is a catalyst for this decomposition and therefore can be written over the reaction arrow:

2H2O2 (aq) + yeast ---> 2H2O (l) + O2 (g)2. The splint will reignite when placed in the flask, because oxygen

supports combustion. Combustion is the chemical combination of a substance with oxygen. An oxide is one of the products.

3. The container must be stoppered (or closed in some manner) to avoid loss of the oxygen, which is less dense than air. Without the stopper the oxygen would escape into the room.

4. The atmosphere is composed of 21% oxygen. If this percentage were increased, any combustion process would proceed at a greater rate.

Safety Precautions1. The flask may become hot due to the exothermic nature of the

reaction. Use care when handling.2. Oxygen gas is flammable! No open flames or sparks should be

near the gas production or storage area.

DisposalAll solid material can be placed in a trash container. All solutions may be poured down the sink.

Experiment #8

Production of HydrogenThe procedure will allow the student to generate hydrogen gas and examine some of its properties.

Materials Substitutions Mossy zinc galvanized nail 3 M hydrochloric acid muriatic acid 125 mL Erlenmeyer flask and stopper small jar Stopper lid Wood splint toothpick Beral pipettes droppers Candle and matches

Procedure1. Place a small amount of mossy zinc or a galvanized nail in the

flask.

2. Add one dropper full of HCl (aq) to the zinc. Gas bubbles will be produced. Stopper the flask loosely.

3. After 20 seconds, light the wood splint from the candle, and prepare to test for the gas.

4. CAREFULLY place the burning splint at the mouth of the flask. Be prepared for the reaction! Replace the lid a wait for more gas to collect.

5. Re-light a splint and test the gas again.

Questions1. Write the equation for the production of the gas in the above

experiment.2. Describe the reaction between the gas and the burning splint.3. Why must the container be stoppered in order for the gas to be

collected?4. What property of hydrogen made it less desirable as the fill gas for

the large dirigibles of the 1920’s and 1930’s?

Experiment #8

Teacher's NotesDuring the sixteenth century a Swiss-German physician named Paracelsus noted that a flammable gas was formed when iron reacted with sulfuric acid. He did not realize that the gas was a pure substance. In 1766, Cavendish determined that the flammable material was a distinct substance when he was able to produce the gas by reacting a variety of acids with several metals. However, it was Lavoisier who named the gas hydrogen, which means, "water producer".

Hydrogen is produced when an active metal replaces this element in hydrochloric acid. This reaction is called a single replacement reaction:

Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 (g)Hydrogen has a density less than air, so we must use a stopper or lid to keep it from escaping. For large commercial ventures hydrogen is generally produced by the electrolysis of water. Hydrogen is liberated at the cathode when a direct current is passed through water containing a small amount of an electrolyte.

Solution PreparationCommercial muriatic acid is a strong acid and therefore must be used with care! Gloves may be worn when working with this chemical. To prepare a 3M solution: slowly add 100 mL of concentrated muriatic acid to 300 mL of (distilled) water. This mixture will get HOT.

Safety Precautions1. Proper eye protection should be used at all times. 2. Hydrochloric acid is corrosive. Proper care should be used to

protect skin and clothing.3. If you are using glass bottles or jars, the containers should be

wrapped with tape to avoid glass fragments if the container is broken or explodes.

4. Hydrogen gas is very reactive! Do not have open flames or sparks near gas production or storage area. Pressure will build up quickly inside the flask or jar, so the container should never be tightly sealed.

DisposalAll solids may be placed in the trash can. Acid solutions should be poured down the sink followed by water to clear the plumbing.

Experiment #9

Production of Carbon DioxideCarbon dioxide can be produced with common household chemicals. This experient observes some of its easily observable properties.

Materials Substitutions Sodium hydrogencarbonate (3g) baking soda Acetic acid (0.80 M) vinegar 125 mL Erlenmeyer flask small jar Beral pipette medicine dropper Wood splints toothpicks Matches and a candle

Procedure1. Measure approximately 3 grams (1/2 tsp.) of sodium

hydrogencarbonate and place it in the flask.

2. Using the pipette, add a few drops of acetic acid to the sodium hydrogencarbonate. Gas bubbles will be formed.

3. Light a wooden splint or toothpick from the candle.

4. Carefully tip the flask and insert the burning splint into the neck of the flask and observe the effect of the gas (carbon dioxide) upon the flame.

5. Using the candle, relight the splint and test the gas again.

Questions1. Write the equation for the reaction occurring in the above

experiment.2. Describe the effect of carbon dioxide on the burning splint?3. What property of carbon dioxide allowed us not to us a stopper or

lid?4. Sine carbon dioxide is often used in fire extinguishers; describe how

you could use this experiment to create your own extinguisher.5. Other chemicals can react to produce carbon dioxide. Compare this

reaction with the one used in Experiment 5 of this book.

Experiment #9

Teacher's Notes1. The equation for this reaction is:

NaHCO3 (s) + HC2H3O2 (aq) ---> NaC2H3O2 (aq) + CO2 (g) + H2O(l)2. Carbon dioxide does not support combustion. Oxygen is the

substance that is necessary for any burning to take place. The splint should be extinguished.

3. The density of carbon dioxide is 1.56 g/mL while that of air is 1.0 g/mL. Since the carbon dioxide is denser than air, it will remain below the air in the container.

4. For the extinguisher, use a plastic drink bottle. Drill a small hole in the screw top, and insert a drinking straw. Place a small amount of baking soda in the bottom of a plastic drink bottle. Add to the container a small container of vinegar. To initiate the extinguisher, tip the bottle to start the reaction, and the carbon dioxide will be formed.

Safety Precautions1. Proper ventilation is required due to the odors of vinegar. 2. The reaction containers should be wrapped with tape. Pressure will

increase if the containers are sealed.

DisposalThe solutions can be poured down the sink with subsequent flushing with water. Unreacted sodium hydrogencarbonate may be dissolved in water and poured down the sink. Solid residues may be placed in the trash can.

Experiment #10

Single Replacement ReactionsThis procedure will allow the student to develop a basic activity series through an exploration of single replacement reactions.

Materials Substitutions Zinc galvanized nail Copper copper wire Aluminum foil 0.1 M CuSO4 0.1 M AgNO3 0.1 M ZnSO4 1 M HCl 8 watch glasses spot plate 8 pipettes

Procedure1. After numbering a spot plate or 8 watch glasses, arrange the solids (using the tip of a spatula) in the respective wells as show on the diagram below:

Zn (s) CuSO4 (aq) Zn (s)Pb(NO3)2 (aq) Al (s) CuSO4 (aq) Zn (s) AgNO3 (aq) Cu (s) AgNO3 (aq) Cu (s)Pb(NO3)2 (aq) Zn (s)HCl (aq) Al (s)HCl (aq) I.II. II I. IV. V.VI. VII.VIII.

2. Add approximately 10 drops of each required solution.

Experiment #103. Record any color changes or gas production in the Data

section.

4. Write a balanced equation for any reactions that occur. Include physical state symbols for the reactants and products.

5. Construct an activity series by listing the elements in decreasing order of reactivity. [e.g. Zn (s)+ Cu2+(aq) ----> Cu (s) + Zn2+ (aq) implies that zinc is above copper in the activity series.]

Data and ObservationsI. ______________________________________________________________________________II. ______________________________________________________________________________III. ______________________________________________________________________________IV. ______________________________________________________________________________V. ______________________________________________________________________________VI. ______________________________________________________________________________VII. ______________________________________________________________________________VIII. ______________________________________________________________________________

Experiment #10

Teacher’s NotesAnticipated reactions are:

I. Zn (s) + CuSO4 (aq) --------> Cu (s) + ZnSO4 (aq)Copper forms on zinc; solution color becomes less blue

II. 2Al (s) + 3CuSO4 (aq) --------> 3Cu (s) + Al2(SO4)3 (aq)Copper forms onto aluminum.

III. Zn (s) + 2AgNO3 (aq) ---------> 2Ag (s) + ZnSO4 (aq)Silver crystals form on zinc solid.

IV. Cu (s) + 2AgNO3 (aq) --------> 2Ag (s) + Cu(NO3)2 (aq) Silver crystals grow on copper solid.

V. Zn (s) + Pb(NO3)2 (aq) ---------> Pb (s) + Zn(NO3)2 (aq) Dull gray lead forms on pieces of zinc.

VI. Cu (s) + Pb(NO3)2 (aq) ---------> No Reaction. Copper will not replace lead.

VII. Zn (s) + 2HCl (aq) ---------> ZnCl2 (aq) + H2 (g) Zinc reacts with acid and hydrogen gas is released.

VIII. 2Al (s) + 6HCl (aq) ---------> 2AlCl3 (aq) + 3H2 (g) Aluminum reacts with acid and hydrogen gas is released.

Activity series that is achievable by the reactions in THIS experiment:

1. Zn (Al) 2. Pb (Al) 3. H 4. Cu 5. Ag

Note that the position of aluminum in this series cannot be determined exactly. It is MORE ACTIVE than Hydrogen.

DisposalAqueous solutions of HCl, Zn(NO3)2, AgNO3, and Cu(SO4)2 may be flushed down the sink. Solutions of Pb(NO3)2 should be evaporated and the solid residue placed in a solid waste disposal container. Solid metals should also be placed in a solid waste container.

Experiment #11

Double Replacement ReactionsThis experiment demonstrates reactions that occur between two aqueous solutions. The driving force for the reaction is the formation of an insoluble product.

Materials Substitutions 0.1 M NaCl 0.1 M CuSO4 0.1 M AgNO3 0.1 M Na3PO4 0.1 M NaOH Spot plate watch glasses (6) Droppers (5)

NaCl (aq)

CuSO4 (aq)

NaCl (aq)

AgNO3 (aq)

Na 3PO4 (aq) NaOH (aq)CuSO4 (aq)

NaOH (aq)

Na 3PO4 (aq)

AgNO (aq)3AgNO (aq)3

CuSO (aq)4

I II III

IV V VI

Procedure1. Number wells 1-6. Place 10 drops of NaCl solution in wells I

and IV, 10 drops of NaOH in wells II and V, and 10 drops of Na3PO4 in wells III and VI.

2. Using the diagram above, add 10 drops of CuSO4 to wells I, II, and III and 10 drops of AgNO3 to wells IV, V, and VI.

3. Note any color changes or precipitate formation in the Data section.

4. Write a balanced equation for the reactions that occur. Include physical state symbols for the reactants and products. If no precipitate occurred, NO REACTION occurred.

Experiment #11

Data and ObservationsWell I.

Well II.

Well III.

Well IV.

Well V.

Well VI.

Experiment #11

Teacher's Notes I. NaCl (aq) + CuSO4 (aq) -------> No Reaction.

II. 2NaOH (aq) + CuSO4 (aq) -------> Na2SO4 (aq) + Cu(OH)2 (s)

III. Na3PO4 (aq) + CuSO4 (aq) -------> No Reaction

IV. NaCl (aq) + AgNO3 (aq) -------> NaNO3 (aq) + AgCl (s)

V. NaOH (aq) + AgNO3 (aq) -------> NaNO3 (aq) + AgOH (s)

VI. Na3PO4 (aq) + AgNO3 (aq) -------> 2NaNO3 (aq) + Ag3PO4 (s)

DisposalAll solids should be collected into a labeled waste solid container. Aqueous solutions can be flushed down the drain in the quantities suggested here.

Experiment #12

Gas Producing ReactionsMany types of chemical reactions produce gaseous substances. These types of reactions may be classified as: single displacement or double displacement. In this experiment, you will investigate these types of reactions.

Materials 3 M HCL Na2CO3 Small pieces of zinc CaCO3 Small pieces of magnesium Spot plate Dropper

Zn (s) HCl (aq)

I.

Mg (s) HCl (aq)

II. III.

Na2CO3 (s) HCl (aq)

CaCO3(s) HCl (aq)

IV.

Procedure1. Place a piece of each solid (Zn or Mg ) or a small amount of

granular solid (using the tip of a spatula) in the wells of a spot plate—as indicated on the diagram.

2. Add 10 drops of 3 M HCl to each of the four wells.

3. Note any bubbling or fizzing indicating the production of a gas in the Data section.

4. Write a balanced equation for the reactions that occur. Include physical state symbols for the reactants and products.

5. There are two different gases produced in this set of reactions. What are the gases? What tests could you perform to verify your hypotheses?

Experiment #12

Data and ObservationsI. ________________________________________________

Identity of gas produced:_____________________________

II. _______________________________________________

Identity of gas produced:_____________________________

III. _______________________________________________

Identity of gas produced:_____________________________

IV._______________________________________________

Identity of gas produced:_____________________________

What are the tests that will verify the identity of these gases?

Experiment #12

Teacher’s NotesI. Zn (s) + 2HCl (aq) ---------> ZnCl2 (aq) + H2 (g)

II. Mg (s) + 2HCl (aq) ---------> MgCl2 (aq) + H2 (g)

III. Na2CO3 (s) + 2HCl (aq) --------> 2NaCl (aq) + H2O (l) + CO2 (g)

IV. CaCO3 (s) + 2HCl (aq) ---------> CaCl2 (aq) + H2O (l) + CO2 (g)

Test for:

H2(g): A burning splint will pop in the presence of hydrogen. Hydrogen is explosive. Remember the Hindenburg? See Experiment 8.

CO2(g): A burning splint will be extinguished in the presence of carbon dioxide. See Experiment 9.

Disposal:Solids should be placed in solid waste containers. Aqueous solutions

canbe poured down the drain with added water.

Experiment #13

Red, White, and Blue I Demonstration

This colorful demonstration displays chemical reactions that can be performed with common substances.

Materials Substitutions Phenolphthalein solution Aluminum foil Magnesium sulfate heptahydrate Epsom salt

6M ammonia household ammonia 3-250 mL beakers 3 clear plastic cups

Glass stirring rod plastic straw

Copper sulfate pentahydrate Roebic Root Killer K-77

Water

Procedure1. Put 5 drops of phenolphthalein solution in the first beaker. This

should be done shortly before the demonstration, since it will evaporate quickly.

2. Dissolve 5 crystals of magnesium sulfate heptahydrate and a little bit of water (3-5 mL) in the second beaker.

3. Dissolve three small (pea-sized) copper sulfate crystals in a small amount of water (3-5 mL) in the third beaker.

4. Wrap the cups with aluminum foil to enhance the curiosity of the audience.

5. Pour the ammonia solution into each cup—using a volume that will render the solution invisible to the audience.

6. Lift the aluminum foil masks to reveal the red, white, and blue colors.

Experiment #13

Teacher's Notes1. The "red" coloration is due to the presence of an indicator,

phenolphthalein, in a base, ammonia.

2. The "white" coloration is due to a precipitate, which forms when MgSO4 reacts with aqueous NH3. Mg(OH)2 is the insoluble white product.

3. The "blue" coloration is due to a complex ion that forms when Cu2+ ions react with aqueous ammonia. The formula for the complex ion is Cu(NH3)4 2+

4. The phenolphthalein solution should be placed in the cup or glass JUST BEFORE performing the demonstration. The indicator is a tincture (a solution of the solid in alcohol) and will evaporate rapidly. After it evaporates, the "trick" will not work.

Experiment #14

Rate of Solution - DemonstrationSeveral factors can increase the rate of dissolutions for a solid. In this demonstration, you will investigate some of these factors.

Materials Substitutions 3-600 mL beakers 3-1 quart jars Stirring rod spoon Mortar and pestle cup and spoon Large hot plate warming tray with 2 burners 1-800 mL beaker sauce pan 2-400 mL beakers 2 measuring cups 3 sugar cubes (sucrose) Balance Club soda (small bottle) Vacuum pump with bell jar attached

Procedure1. Into the three 600 mL beakers (labeled 1, 2, 3), add the following:

Beaker Contents1 300 mL of hot H2O (about 80 oC)2 300 mL of cold H2O (about 20 oC)3 300 mL of cold H2O (about 20 oC)

2. Use a mortar and pestle or the back of a spoon to crush a sugar cube.

3. Drop into beaker 1: one sugar cube; into beaker 2 one sugar cube; into beaker 3, add the crushed sugar from step 2.

4. Using the stirring rod, stir the contents of beaker 2, leaving beakers 1 and 3 unstirred.

5. Observe what happens. Which method increased the rate at which sugar dissolved most? Record your data below. Draw some conclusions based on your observations.

Data and ObservationsRate of Solution for sugar cubes in water – 1st, 2nd, and 3rd

Beaker Contents Order of dissolving1 300 mL of hot H2O

Experiment #142 300 mL of cold H2O3 300 mL of cold H2O

Questions1. How does crushing the solute (sugar) increase the rate of

solution?2. Suppose you had a cube (6 sides) that measured 20 cm x 20 cm

on each face. How much surface area would be exposed to the solvent?

3. What surface area would result if the same cube was crushed into 8 cubes with each face measuring 10 cm x 10 cm?

4. How much area would be exposed if the cubes were crushed further into 8,000 cubes with each face measuring 1 cm x 1 cm?

5. Why does stirring aid the solution process?6. What was the effect of increasing the temperature of the water?

Why?

Experiment #14

Extension1. Carefully open the small bottle of club soda. Do not shake the

bottle prior to opening it. Pour equal amounts into the two 400 mL beakers or measuring cups. Quickly, take the mass of each beaker and record those masses in the Data section.

2. Place one beaker of soda on the hot plate. As the soda heats, what do you observe? Take the second beaker of soda and place it under the bell jar of the vacuum pump. Turn the vacuum pump on. What happens? Is the solution boiling? When the bubbling stops , remove the beaker from the hot plate, let it cool to room temperature (about 5-10 minutes) and reweigh it. Remove the beaker from the bell jar and weigh it. Record the masses below. What was the change in mass?

a. Mass of soda in vacuum pump: Before ________g After ________g

Difference ________g

b. Mass of soda from hot plate: Before ________g After ________g

Difference ________g

3. What do these differences in mass tell you about the solubility of a gas in a liquid?

a) Why should soft drinks be kept in the refrigerator?

b) If you shake a bottle of soda pop before you open it what will happen? Why?

Teacher's NotesPrior to step 1, you may wish to divide the class into groups of 3 students, with each student responsible for one of the three beakers.

The greater the surface area of the solute, the faster the rate of dissolution of the solute. Crushing increases the amount of surface area exposed to the solvent.

1 face (20 cm x 20 cm) = 400 cm2 1 cube (400 cm2 x 6 faces) = 2400 cm21 face (10 cm x 10 cm) = 100 cm2 8 cubes 8(100 cm2 x 6 faces)=4800

cm21 face (1 cm x 1 cm)= 1 cm2 1 cube (1 cm2 x 6)=6 cm2

8000 cubes=48,000 cm2

Experiment #14

Stirring distributes the solute throughout the solution and therefore increases the rate of dissolution. It may actually break the solute up into smaller units therefore mirroring the same effect as "crushing" the solute. Most students will predict that heating the water is the single greatest way to increase solution formation. Ask that the students indicate the fastest technique for dissolution prior to the experiment. They will be surprised to find that, provided the water is not boiling, the sample in the heated water is the LAST to dissolve. Apparently the convection created by the hot solvent is not as effective as a larger surface area in accelerating the dissolution. Point out that packets of sugar and sugar substitutes are granulated and when stirred, dissolve very easily in cold beverages.

Henry's Law states that the mass of a gas dissolved in a given volume of liquid is directly proportional to the pressure of the gas applied. Soft drinks are bottled at 10-15 times atmospheric pressure to increase the concentration of CO2 in solution. Soft drinks are NOT BOILING as the gas is released! There are several grams of carbon dioxide in a small bottle of club soda. Your students might want to estimate the amount of gas they would consume with a 20 oz. soft drink--or the amount that is in a 3-Liter cola! Certainly, some of the mass lost on the hot plate is due to evaporation. Some of the soda (water) will also be lost while the soda is under vacuum—owing to the reduction of vapor pressure of the solvent. You will remember the caution “Do not shake the bottle of club soda before opening it”. Shaking causes carbon dioxide to escape from the solution and the pressure will increase above the liquid, resulting in a premature release of the gas.

Safety PrecautionsThe hot plate should not be too hot! The water used with the sugar cubes must not be boiling (approximately 80˚ C is a reasonable temperature). Any glassware placed on the hotplate should be heat resistant.

DisposalAll solutions may be poured down the sink.

Experiment #15

Ice CreamAdding a solute to a solvent lowers the freezing point of that solvent. This change in freezing point is referred to as a colligative property. In this experiment, you will use the lowered freezing point of water to chill another mixture (ice cream) to the solid state.

Materials 1 quart Ziploc™ bag Sodium chloride or rock salt 1 gallon Ziploc™ bag Ice 1/2 cup milk Thermometer 1/2 cup whipping cream Measuring cups (1, 1/2, and 1/4

c.) 1/4 cup sugar Plastic spoons 1/4 teaspoon vanilla flavoring

Styrofoam™ cups

Procedure1. In a quart Ziploc™ bag, place 1/4 cup sugar, 1/2 cup milk, 1/2

cup whipping cream, and 1/4 teaspoon vanilla flavoring. Seal the bag securely and mix well.

2. Place 2 cups of ice into the gallon Ziploc™ bag.

3. Using the thermometer, measure and record the temperature of the ice in the Data section.

4. Add 1/2 - 3/4 cup of sodium chloride to the gallon bag.

5. Place the sealed quart bag into the gallon bag. Close the large bag securely.

6. Holding the large bag by the top seal, gently rock the bag from side to side. Do not hold the bag in your hands—as it will be cold enough to cause tissue damage to your hands.

7. Continue rocking the bag until the contents of the quart bag have solidified (This should take 10-15 minutes).

8. Measure the temperature of the salt/ice mixture in the gallon bag and record the temperature.

9. Remove frozen contents from quart bag into Styrofoam™

Experiment #15cups. Consume the contents of the cups.

Data and Observations1. Initial temperature of ice _____2. Final temperature of ice mixture _____3. Change in temperature _____

Questions1. Why is sodium chloride added to the ice?2. Why are large crystals sodium chloride used instead of small

crystals?3. Why is sodium chloride placed on icy patches on highways

and steps in the winter?4. Why is sodium chloride used rather than sucrose?

Experiment #15

Teacher’s NotesWhen a substance freezes, the particles arrange themselves into an orderly pattern. This arrangement is called a crystal. When sodium chloride is added to the water, a solution is formed.

The forming of the solution interferes with the orderly arranging of the particles in the crystal. Therefore, more kinetic energy (heat) must be removed from the solvent (water) for freezing to occur. This results in a lower freezing point.

Furthermore, the more particles of solute (salt) added, the more kinetic energy (heat) must be removed. The greater the concentration of solute (salt), the lower the freezing point of the solvent.

Answers to Questions1. Sodium chloride is added to the ice to lower the freezing point

of the ice.2. Large crystals dissolve more slowly than small crystals. This

allows time for the ice cream to freeze more evenly.3. When sodium chloride is placed on the highway or steps, the

freezing point is lowered and the ice melts.4. Sodium chloride is used for three reasons; first, some solids such

as sugar do not dissolve in ice water as well as salt, secondly, salt is an abundant mineral in the form HALITE and is not expensive, and finally when sodium chloride dissolves, it separated into two particles (Na+ and Cl-), lowering the freezing point further. Only advanced students would need to know this concept. It is called ionic dissociation.

Credit: The formula for the ice cream mixture is due to Mr. William M. Black, Kewanee High School, Kewanee, IL.

DisposalThe ice/salt mixture can be poured down the sink. Ziploc™ bags can be washed and reused.

Experiment #16

Daffy DensitiesAll materials have characteristic densities. As long as the materials do not mix or react, the less dense materials will float on top of the more dense layers. This activity can be done as a lab or demonstration and uses 4 solids and 6 liquids to create a colorful column.

Materials Substitutions Graduated cylinder large vase (cylindrical) Ethanol rubbing alcohol (green) Dawn™ dishwashing detergent liquid dishwashing detergent Dark corn syrup Vegetable oil Glycerin Water Food coloring (red and green)

OPTIONAL SOLIDS: Cork stopper fishing cork bobber Solid rubber stopper rubber SUPERBALL 1 small piece of lead a lead sinker 1 small block of oak wood

ProcedureBefore you begin, add red food coloring to the water and green food coloring to the rubbing alcohol.

1. In order, slowly pour the following liquids into a graduated cylinder:

a) Dark Karo syrup (pour without touching the container sides)

b) Glycerin c) Dawn dishwashing liquid (blue)d) Water (with red food coloring added) e) Vegetable oil (yellow) f) Rubbing alcohol (with green food coloring added)

2. Add small samples of the solids listed above, in the order: a)

lead, b) rubber, c) oak, and d) cork. Try to avoid mixing the layers.

Teacher's Notes1. Other solids may be added and their relative densities

determined. Suggested solids include: A new penny (made after

Experiment #161986), candle wax, a wooden toothpick, a small block of pine, and an ice cube

2. Students can complete this as a laboratory exercise. If given some densities as 'knowns', then they should be able to set approximate ranges for the other materials.

DisposalAll liquids can be poured down the sink. Solids may be reused.

Experiment #17

Red, White, and Blue II - DemonstrationThis colorful demonstration illustrates the rule "likes dissolve likes" by combining three immiscible liquids to create a density column.

Materials Substitutions Blue lamp oil red lamp oil Whole milk Light corn syrup Red food coloring blue food coloring Tall form 400 mL beaker tall plastic or glass jar

Procedure1. Wrap the outside of the beaker loosely with aluminum foil so that

you can pour your liquids into the glass and can uncover the glass easily by removing the foil.

2. Add several drops of red food coloring to the light corn syrup and invert several times to mix. (If you are using red lamp oil, substitute blue food coloring.)

3. Slowly pour the three liquids into the glass in the order: a) red colored syrup, b) milk, and c) blue lamp oil. The more slowly you are able to pour the liquids, the less mixing that occurs.

4. Ask the students what color will result from mixing red, white, and blue. Then lift the aluminum foil mask to reveal three layers, with the red syrup on the bottom, white milk over the syrup, and blue lamp oil on top.

Teacher's NotesBecause the milk is not exposed to air, the density column will be stable for several days. The oil will retard spoilage of the milk.

Experiment #17Most discount stores will carry colored lamp oil. The colors available often depend on the season. You can color your syrup differently to adjust for the color of the lamp oil that is available.

The order of mixing isn’t crucial. To obtain maximum separation of the layers you should pour the liquids in the order suggested. There are two points to consider:

a. The relative densities of the liquids determine the order of liquids in the column, with the least dense liquid on the top, the most dense on the bottom.

b. The polarities of the liquids prevent mixing. The oil and syrup will be relatively non-polar, while the milk is relatively polar.

DisposalAll substances can go down the drain with copious amounts of water for disposal.

Experiment #18

OobleckMany of the materials we use every day, like starch, are made up of molecules called Polymers. Poly means "many" and mer means "unit." Because the units of chains are so long, their movement is restricted.

Viscosity is a physical property of liquids that describes their rate of flow. Honey and corn syrup are described as having high viscosities because they flow more slowly than water.

Materials Substitutions 1 500 mL beaker 1 bowl Spatula spoon 1 aluminum pie pan Scissors Water Cornstarch ( 1/2 box)

Procedure1. Pour 1 cup of cornstarch into a bowl or beaker.

2. Continue to add a small amount of water until the solution begins to thicken. Stir carefully! Don't fight the viscosity of the polymer.

3. Pour some of the polymer into the pie pan. Try to cut it as you pour. Tap the polymer in the pie pan with your hands. Pour some of the polymer into your hands and roll it into a ball. Does the ball retain its shape? Form a long rope (snake) with the polymer and pull it apart quickly. What happens? With your spoon, attempt to draw in the polymer. Can you write your name?

Experiment #18

Extension:Try making one of the other non-Newtonian fluids in this lab manual. See Experiments 19 and 20.

Teacher's Notes1. The Oobleck is a non-Newtonian fluid. A non-Newtonian fluid

has properties of both a solid and a liquid and reacts to stress with increased viscosity.

2. Oobleck can make a mess!! Be prepared for your students to have some "play" time. Plenty of paper towels and water should be on-hand.

3. If you are doing this for elementary age students, you may want to add a drop or two of food coloring. Then you can read Dr. Seuss' "Bartholomew and the Oobleck".

4. The mixture of cornstarch and water can be considered a colloidal suspension. A colloidal suspension is a two-phase system in which the starch is not fully dissolved in water but simply mixed into a permanent suspension that will not settle upon standing.

5. Other examples of colloids are: fog, whipped cream, foams, Jell-O, and styling gels.

DisposalOobleck can be spread onto a cookie sheet, dehydrated, and the starch reused!!

Experiment #19

GluepMany of the materials we use every day, like starch, are made up of molecules called polymers. Poly means "many" and mer means "unit." Because the units of chains are so long, movement is restricted.

Viscosity is a physical property of liquids that describes their rate of flow. Honey and corn syrup are described as having high viscosities because they flow more slowly than water.

Materials Substitutions 2-400 mL beakers 2 jars or 2 Styrofoam™ cups Elmer's Glue All Spatula spoon 25 mL graduated cylinder measuring spoons Borax Water Food coloring

Procedure1. Mix 30 mL (2 tbsp.) of glue with 20 mL water (4 tsp.) in a

beaker.2. Add 2 or 3 drops of your choice of food coloring.3. To the second beaker add 200 mL (3/4 cup) of water. Add 2.6

grams (1/2 tsp.) of powdered borax and stir until the borax dissolves.

4. Add 15 mL (1 tbsp.) of the borax solution into the beaker with glue and water.

5. Stir gently allowing it to sit momentarily.6. Take the Gluep out of the beaker and stretch it. Will it

bounce? Does the consistency change? Can you break it?

Experiment #19

ExtensionsTry making one of the other non-Newtonian fluids in this lab manual. See Experiments 18 and 20.

Teacher's Notes1. Gluep is a non-Newtonian fluid--so-called because of its

unusual viscosities. A non-Newtonian fluid has properties of both a solid and a liquid, and reacts to stress with increased viscosity.

2. Glue can make a mess!! Be prepared for your students to have some "play" time. Towels and water should be on-hand as bits of “Gluep” will be on countertops.

3. Caution students not to eat the glue or Gluep.

4. Alternative procedure: Replace the 400 mL beaker in step 1 with a Styrofoam™ cup. Then in step 4, pour the 15 mL of the borax solution into the cup containing the glue/water mixture. This procedure reduces cleanup time.

5. The Elmer’s glue is a solution of a polymer. With the addition of borax, the polymer chains become cross-linked. In this type of reaction, the chains are bonded together to create a larger, stronger polymer.

DisposalIf you have Ziploc™ bags, you could allow the students to take their Gluep home with them. Solutions of borax can be poured into the sinks. Unused mixtures of the borax and glue should be placed into a solid waste container.

Experiment #20

Clear Slime PolymerMany of the materials we use every day, like starch, are made up of molecules called polymers. Poly means "many" and mer means "unit." Because the units of chains are so long, their movement is restricted.

Materials Substitutions 2.46 g sodium borate 1 teaspoon of borax 0.63 g guar gum (1/4 tsp.) 200 mL water 5/6 cup of water 100 mL graduated cylinder measuring cup 2-250 mL beakers 2-9oz plastic cups 2 stirring rods 2 spoons Balance Paper towels Food coloring 4-5 Ziploc™ bags (1 per person)

Procedure1. Pour 100 mL of water into a beaker.

2. Add the sodium borate to the water and stir until the solid is completely dissolved (about 1 minute).

3. Label the solution.

4. Pour 80 mL of water into the other beaker

5. Add guar gum to water WHILE STIRRING. Continue stirring until the solid is completely dissolved (about 1 minute).

6. Label the solution.

7. Add food coloring of your choice to guar gum solution and stir for 1 minute.

8. Add 5 mL of the sodium borate solution to the guar gum solution. Stir for 1 minute then let it sit for 2 minutes.

Experiment #20

Extensions1. Challenge students to modify the basic recipe and

demonstrate each resulting product. Can they create a slime that is stretchy, or one that bounces?

2. Extend the activity into other disciplines by having each team name their new product and create a marketing strategy including packaging, cost analysis, and advertising.

Teacher's NotesThe secret to this colloidal suspension is the guar gum. It is not available through common sources and must be ordered through a chemical company.

This slime can be stored in a Ziploc™ bag so students can take it with them. It’s usual properties will diminish over time as it dries out.

Try the other non-Newtonian fluids in this lab manual! This recipe was adapted from a Flinn Scientific publication and an issue of NSTA Science Scope magazine.

Experiment #21

THE CAT'S MEOWThis activity is used to arouse interest in a common substance, milk. Students are asked to form a hypothesis about the behavior of milk as it is acted on by a household detergent.

Materials Substitutions Large glass Petri dish aluminum pie pan Toothpick wooden splint Liquid dish detergent laundry detergent (liquid) Milk Food coloring - 4 different colors

Procedure1. Pour milk into an aluminum pie pan to a depth of 1 cm (1/2

inch).

2. Add a couple of drops of each of the food colorings near the edge of the container. Arrange the drops so that they are in positions equivalent to 3, 6, 9, and 12 o' clock

3. Dip the tip of a toothpick in detergent. Touch the surface of the milk in the center of the pie pan and hold the toothpick in place for a while. What happens?

4. Experiment with the milk and toothpick. How is it possible that the fairly quiet pan of milk is now exhibiting such activity? Suggest a hypothesis that may explain the phenomena that you observe.

Experiment #21

ExtensionsIf the milk is diluted with water, will the phenomena still occur? Would this take place if low fat milk were used?

Teacher's Notes1. The most important aspect of this activity are the observations,

hypotheses, and conclusions that the students draw. Whether or not they come up with the right answer is not important. Although the phenomena appear to be related to the detergent action on the milk, it has not been proven what causes this activity to occur.

2. Milk is a colloid. It contains not only salts and sugars dissolved in water, but also small globules of fatty substances and protein, which vary in diameter. The fat globules, being hydrophobic, cannot dissolve in the water. They can, however, dissolve in each other.

Average Composition of Milk

Water 87 %Total solids 13 %Proteins (casein) 3-4 %Lipids (triglycerides) 3.5-5 %Sugars (lactose) 4.5-5 %

3. Detergents have a hydrophilic and hydrophobic end in its molecular structure. This structure reduces the surface tension of water.

4. The detergent tries to surround the fat in the milk but the fat is so evenly dispersed that is simply turns over and over. This causes the swirling effect that we notice.

DisposalAll solutions can be poured down the sink.

Experiment #22

Cabbage Juice IndicatorChemists use indicators to test whether a substance is an acid or a base. Indicators work by turning a distinctive color in the presence of an acid or a base. You can make your own indicator from red cabbage. You can also make indicators from the juice of elderberries, blackberries, radish skins, apple skins, or cherries.

Materials Substitutions Hot plate head red cabbage Food processor knife and cutting board 1000 mL beaker large size saucepan 500 mL beaker large jar 4-5 250 mL beakers 4-5 small jars Sieve tea strainer or colander Test substances** Distilled water

** Recommend materials: baking soda, bathroom cleaner (e.g. Formula 409), washing soda, vinegar, lemon juice, milk, cream of tartar, orange juice, milk of magnesia, lime, soft drinks, or ammonia)

Procedure1. Chop red cabbage finely. Boil a pint of water in a saucepan.

2. Add the red cabbage carefully to the boiling water and take the saucepan off the heat. Let it stand for 30 minutes until it is completely cool.

3. Using the sieve, strain the liquid into a jar and throw away the used cabbage. The liquid should be a dark reddish purple color. Add alcohol to reduce the spoilage of the indicator. Use a 1 to 5 ratio of alcohol to volume of water.

4. The color will change as you add acids or bases. To test a substance, pour a little of your substance into a small jar. Then add a drop or two of the cabbage juice indicator. A change in color indicates its acidity or alkalinity.

COLORS OF RED CABBAGE JUICE AT DIFFERENT PH VALUES

Experiment #22ColorRed Rose Purple Blue Green

yellow pH 1 2 3 4 5 6 7 8 9 10 11 12 13 14

ACID Neutral BASE

Data and Observations

Substance Color Approximate pH Acid or BaseLemon juiceLimeWashing sodaAmmoniaCream of tartarMuriatic acidBathroom cleanerVinegarBaking sodaSoft drink

Experiment #22

ExtensionsSoak some filter paper in the cabbage juice indicator. Allow the paper to dry, then cut it into strips. Conduct an "at home" pH test of other household items. Tape your strips to a piece of notebook paper and bring them back to class. Compile your results. What can you say about household cleaners? Where are most household acids found?

Teacher's Notes1. Lemons, vinegar, cream of tartar (potassium acid tartrate),

orange juice, and sour milk will be acidic solutions.

2. Pure distilled water is the only substance listed that should be neutral.

3. Tap water may be slightly acidic—owing to dissolved carbon dioxide. Baking soda is also a weak base.

4. The strong bases will be bathroom cleaners, ammonia, washing soda, milk of magnesia, and lime.

5. The indicator can be frozen in ice trays and saved for later use. The indicator mixed with alcohol will last for months! The strips can also be refrigerated and will last for months as well.

* Canned cabbage may be used as an alternate source of cabbage juice.

DisposalAll solutions can be poured down the sink. Solid bits of cabbage should be put into a solid waste container and emptied at the end of the school day. (Cabbage will begin to smell very badly if left overnight.)

Experiment #23

Invisible Ink - DemonstrationThis demonstration shows that phenolphthalein is a chemical that displays different colors depending on the acidity and the alkalinity of the environment.

Materials Substitutions Phenolphthalein solution Cotton swab artist's paint brush White typing paper roll of paper towels 1-100 mL beaker glass or plastic cup Rubbing alcohol Ammonia Windex spray with ammonia Acetic acid vinegar

Procedure1. Before performing your demonstration roll out one sheet of

paper towel. Dip the swab in the phenolphthalein solution and use it to write a message or draw a picture on the paper towel. Prepare two additional sheets in the same manner. Let them dry in the air. Roll the paper towel back.

2. In front of the audience roll out the paper towel and spray with ammonia or Windex. A message appears in pink ink.

3. Spray the second paper towel with Windex (to which you’ve added acetic acid). Nothing will happen. Spray the third paper towel with Windex (with ammonia) and it works again. Ask the students to explain what happened!

Experiment #23

Teacher's Notes1. Phenolphthalein is an indicator that is colorless in the

presence of an acid. It will turn bright pink in the presence of a base, like ammonia.

2. The same "secret message" sheets may be used repeatedly, if multiple performances are required. I usually tape the tops and bottom of the sheets to a wall or surface that Windex will not harm.

3. You may wish to “spray” the sheets with the “pink message” with CO2 gas.

4. This gas may be obtained by capturing the gas as dry ice sublimes. Alternatively you may make CO2 gas by pouring some acetic acid onto sodium hydrogen carbonate which you’ve placed into a plastic soda bottle.

DisposalPaper towels should be disposed of in a solid waste container. Solutions of acetic acid and ammonia can be stored in suitable containers in the stockroom.

Experiment #24

The Witches' Potion - DemonstrationThis demonstration shows that phenolphthalein is an acid/base

indicator.

Materials Substitutions 2-500 mL beaker 2 large, clear containers 4-250 mL beakers 4 tall glasses Phenolphthalein solution 3 M ammonia (10%) colorless household ammonia 3 M acetic acid vinegar Water

Procedure1. Prepare four 250 mL beakers and label them 1-4. In beakers 1

and 3, put 5 drops of phenolphthalein. In beakers 2 and 4, put 5 drops of ammonia*If you prepare these ahead of time, cover them to reduce evaporation.

2. In one of the large beakers put 20 drops of vinegar. Fill the other large beaker with water.

3. Choose 5 volunteers: 4 witches and someone to read the poem.

Read: "Four witches made quite a commotion When I invited them to create a potion. Into four glasses went the magic brew," STOP

Fill each glass 1/4 - 1/2 full with water. All potions will be clear and colorless.

4. Read: "And into a rage the first witch flew: She shrieked, 'There's no magic in this drink To cast a spell, it must be pink!' The second witch laughed, "The pink is here!" Pour your brew in--the color will appear!" STOP

Have Witch #1 pour her water into the glass of Witch #2. The phenolphthalein will react with the ammonia and turn bright pink, indicating the presence of a base.

Experiment #24

5. Read: "The third witch shrieked, 'We need more!' And gave her brew to Witch number four." STOP

Have Witch #3 pour her water into the glass of Witch #4. The phenolphthalein will react with the ammonia and turn bright pink, indicating the presence of a base.

6. Read: "Now there are two glasses of pink, But no one asked me what I think! I'll invoke my powers to make it clear- 'Be Gone Pink!' 'Watch it disappear!!'" END

Pour both glasses with the pink solutions into the glass container with vinegar. The acid will neutralize the base and the liquid will be colorless again.

Experiment #24

Teacher's NotesPhenolphthalein is an indicator that turns pink in the presence of a base, but is colorless in an acid. Because the phenolphthalein solution is made with alcohol, it will evaporate easily. You should plan to put the solutions in beakers just before the demonstration to reduce evaporation.

DisposalThe solutions can be flushed down the drain.

Experiment #25

Experiment #25

What’s in a Penny?**The procedure will allow the students to use chemical reactions to observe the composition of an alloy

Materials Substitutions Pennies minted after 1982

12 M (concentrated) hydrochloric acidmuriatic acid

2-150 mL beakers & 400-mL beakers small and large jars 6 M NaOH solution Elemental zinc, granulated Metal shears Hot plate Evaporating dish Tongs

ProcedurePercentages of Copper and Zinc in a Penny1. Obtain a penny minted after 1982 and record the mint date. Use

metal shears to cut the edges of the coin in several places.

2. Weigh the penny and record the mass.

3. Under the hood, place the penny into a 150-mL beaker and add approximately 20 mL of concentrated hydrochloric acid.

4. When the coin stops producing gas bubbles, decant the acid into another 150-mL beaker. Record the reaction time.

5. Wash the penny in distilled water. Then rinse with acetone. When the penny is dry, weigh and record the mass of the copper shell.

6. Calculate the percentages of copper and zinc in the penny.

Preparation of Brass Alloy1. Place an evaporating dish under a hood, with approximately 5

g of zinc and approximately 50 mL of 6 M sodium hydroxide. While the volumes are not critical, assure that the zinc is covered with the NaOH solution. With the hot plate, heat the

Experiment #25mixture to boiling. Carefully (with tongs), place the copper shell into the mixture.

2. Leave the coin in the solution until it turns a silver color (about 45 seconds).

3. Remove the coin (with tongs) and dip it into a beaker of water to remove any remaining NaOH solution. Dry the coin.

4. With the tongs, place the coin on the surface of the hot plate (Be careful! It will be VERY HOT). Turn the coin to heat evenly. A gold color will appear. Do not overheat! The gold color will disappear if the coin is overheated.

5. Dip the coin into a beaker of water and dry.

Data Section

Mint date of pennyMass of pennyMass of copperPercentage of copperMass of zincPercentage of zinc

Questions1. List two observations that give evidence of a chemical reaction

occurring between the zinc and the hydrochloric acid.2. What type of reaction is represented in question 1 (gas

producing, precipitation, oxidation-reduction, etc.)? Why?3. Would the reaction of the penny with hydrochloric acid have

occurred if the penny had not been cut?

Teacher's NotesPennies that have been made after 1982 are a composite of zinc and copper. The copper is plated on top of the zinc. What if we could reverse this composite by placing the zinc on top of the copper? The

Experiment #25zinc can be removed from the penny by cutting the coin and creating a reaction between the zinc and the concentrated hydrochloric acid:

Zn(s) + HCl(aq) Zn2+(aq) + Cl - (aq) + H2(g)Copper does not react with hydrochloric acid. After removing the zinc, reweigh the penny and obtain the mass of copper that is present. The remaining copper can be plated with zinc and the brass alloy produced. This process entails first creating a reaction between zinc and 6M of sodium hydroxide:

Zn(s) + 2 OH-(aq) ZnO22-(aq) + H2 (g)The zinc will adhere to the copper. Upon heating, a brass alloy forms.

Answers to Questions1. Two observations: gas evolution; consumption of zinc inside

penny2. Type of reaction represented in question 1: gas producing and

oxidation-reduction. 3. The reaction with HCl occurs only if the HCl contacts the zinc.

Safety Precautions1. Proper eye protection should be used at all times. 2. Handle hydrochloric acid and concentrated sodium hydroxide with

care! Gloves should be worn when working with these chemicals 3. Hydrogen gas, produced in Part A, is very reactive! Do not have

open flames or sparks near gas production or storage area. Pressure will build up quickly inside the flask or jar so the container should never be tightly sealed. Explosions could occur from increased pressure.

DisposalAll aqueous solutions may be flushed down the sink with copious amounts of water. Use care when disposing of concentrated acid since it may spatter when poured into the sink.

*This experiment is based upon similar ones from Hubert Alyea described in “Tested Demonstrations.

Experiment # 26

Formulas PokerStudents can practice writing chemical formulas in a card game.

MaterialsEach deck should contain:1. At least one card with each of the following ions(47cards):

Ba+2 Na+1 Ca+2 Li+1 Pb+2 Zn+2

Be+2 Mg+2 Ag+1 K+1 V+3 Ni+3

Sr+2 Sc+3 Al+3 Hg+2 Sn+1 Rb+1

Cu+2 Cu+3 Fe+2 H+1 Fe +3

NO3-1 NO2 -1 SO4–2 SO3 –2 HSO4 -2 CO3 -2

HCO3-1 PO4 –3 HPO4-2 NH4 +1 OH-1 ClO4 -1

CrO4-1 Cl-1 AsO4-2 C2H3O2–1 H2PO4 -1 I-1

S-2 O-2 F-1 N -3 Br-1 P-3

2. One blank or FREE card

3. Fifteen cards: five with each of the following subscripts: 1,2,3

Procedure1. This game is played as a 5-card draw. The dealer will pass out 5

cards to each player from the shuffled deck, placing all remaining cards in a central stack.

2. Each player may discard as many as 3 cards in one rotation—taking as many cards from the central stack as s/he discards. Play begins with the player to the right of the dealer. Players try to make a chemical formula that uses as many of their cards as possible. If they cannot play, they must pass. It is possible to make two chemical formulas in one play. Once a player uses a number of cards to make a formula, that player should draw, from the central stack, as many cards as s/he used. Play then passes to the player on the right.

Experiment # 263. Total the score by the number of cards that a player is able to use

to make a chemical formula. It is possible for a player to score as many as 5 points per hand. See Sample Score Sheet. Each player has her/his own score sheet.

4. Play continues until no more formulas can be made.

Experiment # 26

Score Card TOTAL

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

Experiment # 26

(SAMPLE) Score Card

TOTAL

1 Mg2+ NO3-1 2 ----- ----- 3

2 Sc3+ ClO4-1 3 ----- ----- 3

3 NH4+1 3 N-3 1 ----- 4

4 V+3 2 S-2 3 ----- 4

5 Na+1 Cl-1 Ca+2 NO3-1 2 5

6

7

8

9

10

11

12

13

14

15

16

17

18

Total 19

Experiment #27

Radioactive Decay of CandiumRadioactive decay processes occur in accordance with first order kinetics. This simulation provides a simple example of the rate at which a radioactive isotope decays.

Materials M&M™ candy pieces Re-sealable bag Graph paper

Procedure1. Place 50 atoms of candium (pieces of candy) in the bag.2. Seal the bag and gently shake for 10 seconds.3. Gently pour out candy. 4. Count the number of pieces with the print side up—and record

the data. These atoms have "decayed". 5. Return only the pieces with the print side down to the bag.

Reseal the bag. 6. Consume the "decayed atoms”.7. Gently shake the sealed bag for 10 seconds.8. Continue shaking, counting, and consuming until all the atoms

have decayed.9. Graph the number of undecayed atoms vs. time.

Data and ObservationsHalf-life Total Time # of Undecayed Atoms # of Decayed Atoms

0

1

2

3

4

5

6

7

8

Experiment #27

Questions1. What is a half-life?2. In the experiment, what was the half-life of the element candium?3. At the end of two half-lives, what fraction of the atoms had not

decayed?4. Describe the shape of the curve drawn in step 9.5. Repeat the experiment three more times, starting with 30 atoms,

80 atoms, and 100 atoms of candium. Compare the resulting graphs.

6. Repeat the experiment using half-lives of 5 seconds, 20 seconds, and 1 minute. Compare the resulting graphs.

Experiment #27

Teacher's NotesSome naturally occurring isotopes of elements are not stable. They slowly decompose by discarding part of the nucleus. The isotope is said to be radioactive. This nuclear decomposition is called nuclear decay. The length of time required for half of the isotope to decay is the substance's half-life. Each radioactive isotope has its own particular half-life. However, when the amount of remaining isotope is plotted against time, the resulting curve for every radioisotope has the same general shape.

Hint: Make sure you use candies with printing on one side (plain M&Ms™).

Answers to Questions1. Half-life is the length of time required for one half of an isotope to

decay.2. The half-life of candium in this activity was 10 seconds.3. At the end of two half-lives, 1/4 of the original sample remained

and 3/4 of the sample had decayed into a new element.4. The graph is a decreasing logarithmic curve.5. The shape of the graphs will be almost the same.6. The shape of the graphs will be almost the same.

Appendix

Comparison of Solutions, Suspensions, and Colloids

Type Particle size PermanenceSolution < 1 nm Permanent

Colloid between 1 nm and 100

nm

Permanent

Suspension > 100 nm Settle out

Properties of Solutions, Colloids, & Suspensions

Solutions Colloids SuspensionsDo not settle out Do not settle out Settle out on standing

Pass unchanged through

filter paper

Pass unchanged through

filter paper

Separated by filter paper

Pass unchanged through

a membrane

Separated by a membrane Separated by a membrane

Do not scatter light Scatter light Scatter light

Affect colligative properties Do not affect colligative

properties

Do not affect colligative

properties

Handy conversions

1 ounce (avoirdupois) = 28.35 grams

1 ounce (liquid) = 29.58 milliliters (mL)

1 tablespoon (liquid) = approximately 10 milliliters (mL)

1 pound = 454 grams

Appendix

Chemicals Used in the Manual(MSD Sheets Should be Present for these Materials)

AppendixAcetic acid (vinegar)

Aluminum foil

Aqueous ammonia

Bathroom cleaner

(Formula 409™)

Borax (Na2B4O7)

Calcium carbonate

Calcium chloride

Club soda

Copper sulfate

Copper wire or foil

Cornstarch

Cream of tartar

(potassium acid

tartrate)

Dark corn syrup

Dawn™ dishwashing

detergent

Dry ice (CO2)

Elmer’s Glue All™

Ethanol

Food coloring (red,

green, and blue)

Glycerin

Guar gum

Hydrochloric acid

Hydrogen peroxide

Ice

Lead nitrate

Lemon juice

Light corn syrup

Lime (CaO)

M&M™ candies

Magnesium sulfate

heptahydrate

Magnesium wire

Milk

Milk of magnesia

(Mg(OH)2)

Orange juice

Pennies

Phenol red

Phenolphthalein

solution (1%)

red or blue lamp oil

Silver nitrate

Sodium carbonate

Sodium hydrogen-

carbonate

Sodium hydroxide

Sodium phosphate

Soft drinks

Steel wool

Sucrose

Vanilla extract

Vegetable oil

Washing soda

(Na2CO3)

Water

Whipping cream

Windex™

Yeast

Zinc (mossy)

Zinc sulfate

Appendix

Chemicals Used in the Manual(MSD Sheets should be present for these materials)

Chemicals found mainly in chemical supply houses:Copper wire or foilGuar gumLead nitrateMagnesium wirePhenol redPhenolphthalein solution (1%)

Silver nitrateSodium hydroxideSodium phosphate Zinc (mossy)Zinc sulfate

Chemicals found in grocery/hardware/pool or agricultural supply stores:

Grocery

Acetic acid (vinegar)Aluminum foil Aqueous ammonia Bathroom cleaner (Formula 409™) Borax™ CornstarchCream of tartar (potassium acid tartrate) Dark corn syrupDawn™ dishwashing detergent Dry ice Elmer’s Glue AllFood coloring GlycerinHydrogen peroxide IceLemon juice Light corn syrup M&M™ candies Magnesium sulfate heptahydrate (epsom salts) MilkMilk of magnesia Orange juiceRed or blue lamp oilSodium carbonate (washing soda)Sodium hydrogen carbonateSoft drinks Steel wool Sucrose Vanilla extract Vegetable oilWaterWhipping cream Windex™ Yeast

Hardware/Pool/Agricultural Supply

Calcium carbonate (chalk)Calcium chlorideCopper sulfateEthanol (Everclear) ABC storeLime (CaO)- agricultural supply Hydrochloric acid (muriatic acid)

Sites for obtaining Material Safety Data Sheets (MSDS)

Having a MSD Sheet for every chemical in your stockroom is a legal requirement—not just a good idea. With that in mind, manufacturers ship MSD sheets with all chemicals. However, a typical stockroom contains many older chemicals that may not have arrived with an MSDS. Obtaining one is vital.

Below are some sites from which MSD sheets can be downloaded. Please note that URLs frequently change. Below are listed sites that have been relatively stable for some time. In the event that these sites have moved, enter “MSDS” into a search engine (e.g. GOOGLE) to obtain updated URLs for MSDS sources.

1. The National MSDS Repositoryhttp://www.msdssearch.com/

2. A regularly updated site with free resources for material safety data sheets sites http://www.ilpi.com/msds/

3. The Physical and Theoretical Chemistry Laboratory Oxford University Chemical and Other Safety Information http://physchem.ox.ac.uk/MSDS/

4. The MSDS HyperGlossaryhttp://www.ilpi.com/msds/ ref/

Safety SoftwareThe state of North Carolina provides science teachers a software package “Teaching Science Safety” by Jack Gerlovich for public schools (in both Mac and PC formats). Call the NC Department of Public Instruction (Secondary Science Division) for information on obtaining a copy of the software. The package contains valuable information on liabilities, many printable blank forms, safety tips, a spreadsheet for your stockroom inventory, and more.

COMPOUND FORMULA COMMERCIAL SOURCEEQUIVALENT

acetic acid CH3COOH vinegar ( 5% ) grocery storeacetone CH3COCH3 acetone hardware storeacetylsalicylic acid C9H8O4 aspirin drug storealuminum Al foil or wire grocery or hardware

storealuminum potassium sulfate

KAl(SO4)2 alum drug store

aluminum sulfate Al2(SO4)2 flocculating powder pool supply storeammonium carbonate (NH4)2CO3 smelling salt drug storeammonium chloride NH4Cl sal ammoniac drug storeammonium hydroxide NH4 (aq) ammonia cleaner (10%) grocery storeammonium nitrate NH4NO3 nitrate of ammonia garden supply storeamylose (C6H10O5)n cornstarch grocery storeascorbic acid C6H8O6 vitamin C drug storeboric acid H3BO3 boric acid eyewash

solid roach killerdrug storehardware store

butane C4H10 disposable lighter fluid

grocery store

caffeine C8H10N4O2 No-Doz™ tablets drug storecalcium carbonate CaCO3 white chalk,calcium

supplementdrug store

calcium chloride CaCl2 "De-Ice" for sidewalks grocery storecalcium hydroxide Ca(OH)2 slaked lime, some

antacidshardware storepool supply store

calcium oxide CaO Quicklime™ hardware storecalcium phosphate, monobasic

Ca(H2PO4)2 superphosphate garden supply store

calcium sulfate CaSO4 plaster of parisgypsum

hobby shopbuilding supply store

COMPOUND FORMULA COMMERCIAL SOURCEEQUIVALENT

carbon C charcoal,graphite hardware storecarbon dioxide-solid CO2 dry Ice dairies, grocery storecarbonic acid H2CO3 soda water grocery storecitric acid C6H8O7 sour salt grocery storecopper Cu sheet, pipe or wire hardware storecopper sulfate,

pentahydrate

CuSO4 •5H2O Bluestone™ algaecideRoot Eater™

hardware or lawn & garden center

DMSO (CH3)2SO solvent drug stores95% ethanol C2H5OH Everclear™ liquor storeethanol/ethyl alcohol CH3CH2OH denatured alcohol hardware or paint shopethylene glycol CH2OHCH2OH antifreeze auto supply storefructose C6H12O6 fruit sugar grocery storeglucose C6H12O6 dextrose drug storeglycerol C3H8O3 glycerin drug storehelium He helium party shopshydrochloric acid HCl (aq) muriatic acid

masonry cleanerhardware store or lawn & garden store

hydrogen peroxide H2O2 3% antiseptic peroxide Clairoxide (12%)

drug storesbeauty supply store

indicators beet juice, red cabbage juice, cherry juice

grocery store

iodine I2 iodine drugstoreiron Fe uncoated nails, filings

steel woolhardware store

iron (III) chloride FeCl3 none drug storelactic acid C3H6O3 milk acid grocery storelead Pb fishing line sinker sporting supply storemagnesium hydroxide Mg(OH)2 milk of magnesia drug store2-propanol CH3CH(OH)CH3 rubbing alcohol drug store

COMPOUND FORMULA COMMERCIAL SOURCEEQUIVALENT

magnesium sulfate, heptahydrate

MgSO4•7H2O Epsom salts drug store

methanol CH3OH methyl alcohol,duplicator fluid,gasoline “dryer”

paint storeoffice supply storeauto supply store

methylene blue C16H18CN3S methidote antisepticbiological stain

veterinariantropical fish store

naphthalene C10H8 moth balls hardware storenujol mineral oil, baby oil drug storeoil Hydrocarbon

(formula varies)vegetable oil grocery store

oxalic acid C2H2O4 rust removerradiator cleaner

drug store hardware store

para-dichlorobenzene C6H4Cl2 moth flakes hardware storeparaffin paraffin wax, candles grocery storephenol red C19 H19SO5 swimming pool indicator swimming pool supplyphosphoric acid H3PO4 pH Down (30% solution) tropical fish storepotassium aluminum sulfate

KAl(SO4)2•12H2O potassium alum photo supply store

potassium bitartrate, potassium hydrogen tartrate

KHC4H4O6 cream of tartar grocery store

potassium bromide KBr potassium bromide photo storepotassium carbonate K2CO3 potash agricultural supply storepotassium chloride KCl lite salt grocery storepotassium dichromate K2Cr2O7 none photo supply storepotassium hydroxide KOH caustic potash hardware or ceramic

shoppotassium nitrate KNO3 saltpeter drug store

COMPOUND FORMULA COMMERCIAL SOURCEEQUIVALENT

potassium permanganate KMnO4 "Clearwater" (53% soln.) tropical fish storesodium bicarbonate,sodium hydrogen carbonate

NaHCO3 baking soda grocery store

sodium carbonate Na2CO3 washing soda grocery storesodium chloride NaCl plain table salt -uniodized grocery storesodium hydroxide NaOH drain opener (LYE) hardware store

or farm supply storesodium hypochlorite NaClO bleach (5% Sol’n) grocery storesodium nitrate NaNO3 Chile saltpeter garden supply storesodium phosphate Na3PO4 trisodium phosphate

(TSP) paint or garden shop

sodium silicate Na2SiO3 water glass hardware storesodium tetraborate decahydrate

Na2B4O7.10 H2O borax grocery store

sodium thiosulfate Na2S2O3 hypo photo storestearic acid C17H35CO2H candle hardener hobby shopsucrose C12H22O11 table sugar grocery storesulfur S sulfur lawn & garden shopstin or copper Sn, Cu metal sheets hardware store

builders supply storevermiculite gardening soil lawn & garden centerzinc Zn galvanized nails hardware store