ChemShorts for Kids   --   2012
Copyright ^©2012 by the Chicago Section of the American Chemical Society

Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

Kids, did you ever wonder why the snow in movies never seems to melt?  You too can make a version of fake “Hollywood” snow using a common polymer. The fake snow is non-toxic, feels cool to the touch, lasts for days, and looks similar to the real thing.  All you need is water and the polymer called sodium polyacrylate.

Procedure:

1. You can harvest the polymer, sodium polyacrylate, from inside disposable diapers or you can buy crystals in a garden center that are used to help keep soil moist.  For the first route, carefully cut open one or two diapers and separate the beads that are inside from the cloth fibers.
2. Just one or two teaspoons of the beads are enough to get started. Place them in a disposable cup and add some water, then mix the gel. Add more water until you have the desired amount of wetness. The gel will not dissolve, or melt. It's just a matter of how 'slushy' you want your snow.
3. Sodium polyacrylate 'snow' feels cool to the touch because it is mainly water. Place the fake snow in the refrigerator or freezer until well cooled to make it very realistic. If it dries out, you can rehydrate it by adding water.  If you want drier snow, you can add more polymer or reduce the amount of water the polymer can absorb by adding a small amount of salt.

Tips:

1. Fake snow is non-toxic, as you would expect from a material used in disposable diapers, but it is not edible.  When you are done playing it is safe to throw away.
2. Sodium polyacrylate is also found in fire-control gels, those toys that grow when you add water, and floral gel. The super-absorbent chemical is sodium polyacrylate [monomer: -CH₂-CH(CO₂Na)- ], which was invented by scientists at Dow Chemical Company and results from polymerizing a mixture of sodium acrylate and acrylic acid.
3. How does sodium polyacrylate absorb? Read the second link below for the details.

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References:
Anne Marie Helmenstine at About.com: Chemistry
http://chemistry.about.com/od/chemistryhowtoguide/ht/fakesnow.htm
http://chemistry.about.com/od/howthingsworkfaqs/f/diapers.htm

Kids, what kind of trash bag breaks down fastest? As you probably know, trash is a weighty (pun intended) topic in this country. With only so much landfill space available, chemists and environmentalists are looking to other means of disposing trash. Most of the plastic bags in landfills are not environmentally friendly because they take many years to completely degrade.
 
In this experiment the biodegradability of several plastic bags, brown paper bags, and newspaper are tested in different environmental conditions: direct sunlight, a mulch pile (to simulate an ‘active’ landfill), a leaf pile (to simulate a dry landfill), in tap water (to simulate a lake), and in saltwater (to simulate an ocean). You’ll have to plan ahead because results take at least three months.  Also get an okay from your parent or guardian before starting. Trust me, adults will not be amused to come home and find that you've begun this without their knowledge. Besides you may need their help.

Materials:

• Ten plastic trash bags marketed as biodegradable.  Use five each of two different brands as follows.  NOTE!  If the bags contain polyethylene plastic they are not biodegradable, but rather a plastic mixed with a chemical additive that breaks the plastic molecular structure and disintegrates. This is not considered to be overall an eco-friendly process. Eco-friendly vendor certifications should be ASTM D6400 and/or DIN EN13432. If the price of the biodegradable plastic bag is close to that of plastic bags, then they probably have the additive (they may say “oxo” or “oxy” in the name). 
• 5 nonbiodegradable plastic bags
• 3 nets (plastic or cotton)
• wire or string
• 6 wooden posts
• 5 brown paper bags
• 5 pages of newspaper
• a mulch pile 4 feet (120 cm) high consisting of grass, leaves, rotting vegetables, fertilizer, and compost starter culture in a 3-foot (1 meter) diameter ring made of wire fencing
• tap water
• a leaf pile 3 feet (1 m) high
• 10 plastic containers (½ gallon (2 liters) each)
• saltwater (15% by volume)

Procedure:

1. Fold and secure the plastic bags on top of a net with wire or string and identify them. Tie a wooden post at each end of the net and place each post into the ground, leaving the plastic bags exposed to the sun. Do the same with one paper bag and a page of newspaper.
2. Repeat step 1 by placing the same types of bags in the middle of a mulch pile. Wet the pile thoroughly with water.
3. Repeat step 1 by placing the bags in the middle of the leaf pile.
4. Place the bags into five separate containers of tap water and saltwater.
5. Record the changes that occur upon removal after at least 3 months; photos are useful.

Results:

1. Did any of the materials decompose? If so, which decomposed most thoroughly?
2. Was the rate of degradation greatest in the sunlight, mulch pile, leaf pile, tap water, or saltwater environments?
3. Did the plastic bags that were advertised as biodegradable appear any different from the nonbiodegradable bags?

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Resources & References: 

http://www.infoplease.com/cig/science-fair-projects/kind-trash-bag-breaks-down-fastest.html
Excerpted from The Complete Idiot's Guide to Science Fair Projects © 2003 by Nancy K. O'Leary and Susan Shelly. Alpha Books, Penguin Group (USA) Inc.

http://www.biodegradableplasticbags.org/

http://www.education.com/science-fair/article/biodegrade-plastic-paper-newspaper/ 

Kids, have you seen those drinks with the floating edible eggs or beads in them?  You can apply chemistry to make edible eggs or beads, and you can even make them change color.

You’ll need:

• 1 tablespoon sodium alginate
• 1 tablespoon sugar
• 1-2 teaspoons baking soda
• 1 can frozen concentrated grape juice
• 1 teaspoon calcium chloride
• 3 antacid tablets (with magnesium hydroxide)
• large glass, spoon, pipette or dropper, jar with lid, strainer or slotted spoon

Make the Eggs

1. Mix together the sodium alginate and sugar.
2. In a separate container, add baking soda to the grape juice, a pinch at a time. Stir and wait until no more bubbles form before adding a pinch more baking soda. Continue this until very few bubbles form. The alkaline baking soda is neutralizing the acidic grape juice. You want to neutralize the grape juice because you need a higher pH in order to dissolve the sodium alginate.
3. Pour the sodium alginate and sugar mixture into the jar. Stir in the neutralized grape juice.
4. Tighten the lid on the jar and shake it to thoroughly mix the contents. Allow the jar to sit overnight so that the sodium alginate will become fully hydrated.
5. Crush the antacid tablets and mix them together with the calcium chloride.
6. Stir the calcium chloride and antacid into a large (12-16 oz) glass of water.
7. Now comes the part where you make the gel beads! Use the dropper or pipette to suck up some of the grape juice solution. While stirring, slowly drip the juice solution into the glass of water, calcium chloride and antacid. Drip the grape juice solution into the glass from above -- if the dropper comes into contact with the antacid solution then the grape juice solution will solidify in your tube.
8. Leave the eggs or beads in this solution until they turn blue.

Color Change Gel Eggs

Use a slotted spoon or strainer to remove a spoonful of the gel eggs. Add them to an acidic drink, like lemonade or lemon-lime soda or white wine and watch the acidity of the drink change the color of the eggs from blue to red! A carbonated beverage is extra fun because the gel eggs will float up and down with the bubbles.
Supplies:  Sodium alginate can be found in grocery and health food stores. Frozen, concentrated, deeply-colored grape juice is best; bottled concentrate is ok. Calcium chloride is at grocery stores where the pickling and canning chemicals are sold, or from home supply stores in the dessicant area.

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References: 

Anne Marie Helmenstine at About.com: Chemistry
http://chemistry.about.com/b/2012/01/06/color-change-gel-eggs-food-chemistry-project.htm

Kids, did you know that you don't always need a wick and wax to make a candle? All you need for this alternative is a clementine and some olive oil. The clementine acts as a natural wick for the oil. A candle works by vaporizing wax or oil by burning, via a chemical reaction that produces water and carbon dioxide from oxygen and the carbon-based oil. It's a clean process that also yields heat and light.

You’ll need:

• clementine (you could try another citrus fruit)
• olive oil (you could experiment with other vegetable oil)
• an adult partner to use a long-handled lighter

The steps:

Cut the clementine in half and carefully peel away the fruit, leaving ALL of the white part, called the pericarp or albedo, intact and exposed.  This includes the edges near the rind AND the center piece. The pericarp consists primarily of pectin, which is a plant polymer like the cellulose you would find in an ordinary candle wick. The pericarp, by the way, is high in vitamin C. Your goal is to have half of the fruit peel intact, and dry. If you made a mess with the juice, dry your rind off.   Once the rind is prepared, pour a small amount of olive oil into the "candle."  It really doesn't take very much, plus you want the "wick" to remain well exposed and not drowned in oil.

Have an adult partner light the candle.  It might light right away or it could take a few tries. If the pericarp "wick" chars rather than lights, then rub a bit of olive oil into it and try again. Once the candle is lit, it burns very cleanly. Although the bottom shouldn’t get hot, you may want to place the candle on a heat-safe surface just to be safe. The candle should go out on its own once the oil is used up, but do not ever leave it unattended.
 
If desired, clean out the other half of the clementine, cut a hole in the top of the rind, and place on top of the burning bottom half.  The hole will ensure that the candle gets enough oxygen. Cutting into the rind is a nice way to add a decorative flair to the project.  Also, you may wish to watch a video showing how to make a clementine candle.

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References: 

Anne Marie Helmenstine at About.com: Chemistry
http://chemistry.about.com/od/funfireprojects/ss/Clementine-Candle.htm

Kids, a baking soda and vinegar volcano is fun but there are better models for how a volcano actually works.  In this activity, wax "lava" forms a volcano in sand, eventually erupting into the atmosphere, which is water in this model. A real volcano forms and erupts because molten rock (magma) and hot gases push up from the Earth's mantle into the crust. This material pushes up through the weakest spot in the crust to be released as an eruption.  In this model, wax in the bottom of the cup is heated and becomes molten.

You’ll need a candle as a source of wax (try red or orange wax for realistic lava), sand, water, and a heat-safe clear glass cup or glass.

Make the Volcano

1. Have an adult partner light the candle and drip wax into the bottom of the cup.
2. Cover the wax with a layer of sand. The thickness of the wax and sand layers will affect the way your volcano erupts. If you have a thin sand layer, the wax will readily rise up through it. If you have a thick sand layer, the wax will have a harder time erupting through the sand. Thicker layers will produce a more cone-shaped volcano, but you may need to apply more heat or the "magma" may be unable to erupt.
3. Add water to nearly the top of the cup and let the sand settle.
4. Have an adult partner carefully and gently heat the bottom of the cup. A safe (though slow) method is to set the cup in a shallow pan of water. Heat the pan over low heat on a burner on a stove or hot plate. Don't apply too much heat or raise the temperature too quickly or else the cup may shatter! The water will offer protection for the glass. Heat the cup until your volcano erupts.
5. This project is repeatable. After your volcano erupts, turn off the heat and let the cup cool. Remove the sand and wax from the cup. You can re-attach the wax to the bottom of the cup by melting a few drops of wax into the cup. Stick the other pieces to the melted spot. Add sand and water and try again.
6. The wax pushes its way through the gaps between the said grains, much like magma pushes up through rocks.  You’ll get clouds of wax “ash” in your watery atmosphere.  You can experiment with the amount of wax, quantity and type of sand and intensity of heat to form different types of volcanoes.

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References: 

Kids, did you ever hear of a crystal radio kit?  More on that in Part II of this activity, but here we will make an essential ingredient.  Rochelle salt can be used to grow very large single crystals that exhibit piezoelectricity.  This property means the creation of electricity resulting from pressure in the form of mechanical stress.  As a result these crystals can be used as transducers in microphones.  

Rochelle salt is also called potassium sodium tartrate with the molecular formula of KNaC₄H₄O₆•4H₂O.  Unless your adult partner works in a lab, you probably don't have this chemical lying around.  But you can make it in your own kitchen!

Make sodium carbonate (also called washing soda, Na₂CO₃) by having your adult partner heat the contents of one half of a box of sodium bicarbonate (also called baking soda, NaHCO₃) spread thinly in an oven-safe pan at 275°F for an hour.

Have your adult partner heat a mixture of about 80 grams cream of tartar (KC₄H₅O₆) in 100 milliliters of water to a boil in a saucepan.  Remove from heat.  One teaspoon at a time, slowly stir the sodium carbonate powder into the cream of tartar solution. The solution will bubble after each addition, so stir until bubbling stops. Continue adding sodium carbonate until no more bubbles form.

Chill this solution in the pan in the refrigerator. Crystalline Rochelle salt will form on the bottom of the pan. Carefully save your Rochelle salt aside for Part II of this activity which will appear in our next edition.

Notes: 

1.  Use a stainless steel, or better yet, a Pyrex saucepan -- not an aluminum pan to dissolve the cream of tartar.  The cream of tartar could leach some metal out of an aluminum pan which might interfer with your experiment.

2.  There are some examples of artificial cream of tartar on the market shelves;  check the lable to make sure the product you buy is the real thing. 

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References: 
http://www.ehow.com/how-does_5467738_process-making-piezo-crystals.html

Anne Marie Helmenstine at About.com: Chemistry
http://chemistry.about.com/b/2011/05/05/how-to-make-rochelle-salt.htm?nl=1