ChemShorts for Kids   --   1996
Copyright ©1996 by the Chicago Section of the American Chemical Society

by Dr. Kathleen A. Carrado, Argonne National Labs

ChemShorts Home

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

Indigo Imprints

Kids, in this experiment we will be making imprints of objects and then coloring them "chemically" to a beautiful blue-purple (indigo) shade. You will need a 3-inch square piece of architect paper, any solid object to imprint (key, coins, paper cut-out letters, etc.), an empty, clean peanut butter jar with its lid, 1/2-cup household ammonia, several small rocks or pebbles to cover the bottom of the jar to about 2-inches in height, and a bright light (such as a desk lamp).

Place your solid object on the yellow side of the architect paper. Let it sit under a bright light for about five minutes. While waiting, place the rocks in the jar and have your adult partner add the ammonia. Make sure the liquid is just below the surface of the rocks. Cover the jar tightly with the lid. Remove your solid object from the light and notice the "imprint" it left on the paper. Open the jar and carefully place the paper inside, taking care to not let the paper touch the ammonia. Re-cover tightly and observe the paper for about 5-10 minutes.

The ammonia fumes will turn the imprint a deep blue purple color, leaving the rest of the paper alone. The light has chemically altered the unprotected surfaces of the paper so that it will no longer react with the ammonia, which is a chemical base. Architect paper is a very light-sensitive material, but your object has protected and preserved a small portion of it.

When you are finished, have your adult partner pour the ammonia down the drain and clean the jar and rocks with warm soapy water.

Take care not to inhale the ammonia fumes at any point during your experiment.
Submitted by Kathleen A. Carrado, Chair
Elementary Education Committee
Reference: Phil Parratore, Wacky Science: A Cookbook for Elementary Teachers, Kendall-Hunt Publ., Dubuque, Iowa, 1994, page 76.

Bubble Gum Chemistry

Kids, all you really have to do in this "experiment" is chew your favorite kind of gum for a while. Think about what you learn here while you are chewing...

Bubble gum is a mixture of several chemicals, but rubber is the most important. A good bubble gum must be strong enough to stretch to a thin film without breaking, but still be soft enough to chew easily. That's a tall order. The other chemicals in bubble gum - resins, waxes, fillers, flavors, sugar, humectants, and emulsifiers - are all there either to provide flavor or to modify when and by how much the rubber stretches. Rubber molecules are polymers, which are long chain-like molecules formed when many smaller molecules bond together end to end. A natural polymer called latex, which is from trees, used to provide the stretchy part of bubble gum. Now many gum companies use a synthetic, food-grade version of the same rubber that goes into truck tires! This polymer is a mixture of styrene and butadiene and is abbreviated SBR.

Of the 20 or so chemicals in bubble gum, some dissolve in water and some do not. Most of the water-insoluble portion of bubble gum is called "gum base". That's where the rubber is. Some of the additives in the gum base actually restrict the size to which the bubbles can be blown on purpose, so as not to completely alienate parents! The most intense fragrances and flavorings in fruits are often essential oils like limonene (which is from orange and lemon rinds). They are well suited to gums because they are not water soluble and do not dissolve out of gum in your mouth. Gum does seem to lose flavor after a while, but that is usually because the sugar, which intensifies the fruit flavor, has dissolved.

Chemists must think of not only how the gum tastes and how big the bubbles get, but also how it feels in the mouth. It must soften without getting gooey, take up water without dissolving, and keep its flavor for as long as possible. On top of all that, it must not dry out on store shelves, should not stick to the wrapper, and be easy to work with in the factory. Chemists know how to tweak all the ingredients to make a formulation that is just right; who knew a simple thing like gum could be so complicated!
Submitted by Kathleen A. Carrado, Chair
Elementary Education Committee
Reference: Gail Marsella, ChemMatters, October 1994 (American Chemical Society, 1155 16th St., N.W.; Washington, DC 20036).

Sugar and Spice

Kids, in these activities you will be making some home-grown sugar gems into rings and also modifying some spices to make necklaces or bracelets.

Sugar Gems. Granulated sugar is made up of ground-up sugar crystals. Have an adult help you slowly and carefully dissolve 2 cups of sugar into 3/4 cup of boiling water. Let the solution cool slightly, and then pour it into paper cups or clear plastic glasses. Set them aside where they won't be disturbed. As the water evaporates, crystals of sugar (sucrose, C12H22O11 ) will begin to form on the bottom and sides of the cup. Unfortunately, the faster the water evaporates, the smaller the crystals will be. Be patient. Crystals the size of peas will form in a month or so, depending on the temperature and humidity. You can buy jewelry settings at a craft store and attach your best gems singly or in groups. If you want to grow large single crystals, you'll have to use special techniques described in books on crystals at the library.

Spice Jewelry. Spices are used by cooks to add flavor and aroma to foods. No one pays much attention to their appearance. But some spices are attractive and can be used as beads in unusual necklaces or bracelets with a nice smell. First we will consider cloves, which are dried flower-buds grown in places like Zanzibar and Sumatra. The aromatic oil of cloves is called eugenol (C10H12O2 ). Another good one is allspice, which is the aromatic dried berry of the pimento. This also contains eugenol, and is grown in places like the Indies and South America. Soak whole cloves (these are round) and allspice (this is flute-shaped) in water for a day or two until they are soft. Using a needle threaded with nylon thread or even dental floss, pierce the spices and run them onto the thread in your own designed pattern. The allspice can be pierced either lengthwise (down the middle of the long axis) or crosswise (to give a tooth-like appearance). When completed, the spices will dry back to their original shapes and will be held firmly on the thread.
Submitted by Kathleen A. Carrado, Chair
Elementary Education Committee
Reference: Don Herbert, Mr. Wizard's Supermarket Science Random House (NY) 1980, p. 22-25.

Leak Busters

Kids, today we'll prove that helium leaks out from regular balloons and what can be done to stop it. Did you ever buy a balloon bouquet for someone? You probably know that you can't just make one yourself, because balloons filled with normal air don't float like the ones with helium do. And you may have already learned that this works because helium gas is lighter, or less dense, than the gases in regular air (nitrogen and oxygen). So you have to buy balloons filled with helium. But the gift shops now know certain tricks. Leaking helium molecules were a real problem for people who deliver balloon bouquets to parties. Their customers used to often complain that the helium balloons drooped within a day, or even overnight.

You can prove that this droopiness is due to a gas leak by doing the following test. Get a regular balloon, a bottle of vanilla extract (or almond or orange), and a glass of water. Pour two capfuls of the vanilla into the balloon and then blow it up with air and tie it. Set the balloon on the glass so that the knot is under water. Leave this set-up overnight in a confined space, such as a closed bathroom or closet. Your nose should then help you solve the mystery. A balloon's surface has lots of tiny holes that can be seen only with powerful magnifiers, and vanilla molecules are small enough to eventually leak through this surface. Helium molecules are much smaller than air or vanilla molecules, and so they leak out even faster.

What can be done to slow this leakage and make the balloons last longer? A chemist (a "leak buster") invented a chemical called Hi-Float® to slow down the leaks. Hi-Float® coats the inside of balloons with a special stretchy film with very small holes. It makes it harder for the helium molecules to leak through the walls of the balloons. Some will float for as long as 15 days! Now in gift shops they will often ask you if you want Hi-Float® used in your balloons. The shiny foil balloons made from Mylar® are also leak busters. Their surface has virtually no holes at all so they can stay filled for several weeks.
Submitted by Kathleen A. Carrado, Chair of the Elementary Education Committee
Reference: WonderScience (American Chemical Society), November 1986.

The Art of Bleaching

Kids, people use liquid laundry bleach to remove unwanted color, in other words stains, from clothes. This bleach is a 5% solution of sodium hypochlorite in water. It also removes color from other materials and we will use this today to produce some interesting effects. First of all though, you must do this with an adult partner because of the care that must be taken when handling bleach. So get your adult partner, a bottle of laundry bleach, colored construction paper, spoons, brushes, cotton swabs, steel wool, and drinking glasses.

The colors of construction paper quickly disappear with the application of bleach. The trick is to apply and spread bleach in a manner that will result in an artistic pattern. Pour a small amount of bleach into a glass, and then experiment with different applicators, such as a spoon, brush, and cotton swab. Spread the bleach around on the paper by folding, tilting, and blowing through a straw. A little bit of bleach goes a long way, and you'll be able to see the patterns almost immediately. Let your work of art dry before hanging it up for all to see.

In this case the bleaching action can also be called an "oxidizing" reaction. You can prove that oxygen is made from bleach by putting two small balls of steel wool (of the same size) into two different glasses. Cover them with equal amounts of water. Add a tablespoon of vinegar to each glass, and then to just one of them also add a tablespoon of bleach. After about half an hour the steel wool without bleach should be unchanged, but the ball with the bleach should be very rusty. Rust is iron (from the steel wool) that has combined with oxygen in the presence of water. While iron rusts easily, it happens very quickly here because the bleach is producing so much oxygen!

[SAFETY NOTES: Do not leave children unattended while working with bleach. Do not let the bleach come into contact with skin or eyes; if it does flush immediately with large amounts of water. Thoroughly clean or dispose of all materials that came in contact with bleach.]
Submitted by Kathleen A. Carrado, Chair of the Elementary Education Committee
Reference: Mr. Wizard's Supermarket Science, by Don Herbert, Random House: NY, 1980, pg. 45.

Light on a Stick

Kids, you have probably seen a Light Stick, a plastic tube that is often stored in an emergency survival kit instead of a flashlight. Once activated, the Light Stick glows brightly for many hours. Did you ever wonder how it can do this? The process is called chemiluminescence. Fireflies and light sticks make "cold light" from this chemical reaction that makes light without making any heat

The "cold light" given off by living things is called bioluminescence. Certain kinds of moss glow in the dark, and rotting tree stumps give off an eerie light that is called foxfire. Many cases depend on bacteria. The flashlight fish, for example, lives very deep in the ocean where it is absolutely dark. They have sacs of luminous bacteria near their eyes. The bacteria glow all the time, but the fish can cover and uncover the sacs with flaps of skin. They search for food with these lights, blink to attract other flashlight fish, and confuse their predators by flashing and then quickly changing direction.

Bacteria and fireflies make their cold light by mixing chemicals called luciferin, luciferase, oxygen, and ATP (adenosine triphosphate). This reaction has even been developed into a sophisticated medical test for treating tuberculosis (TB). Saliva samples taken from TB patients are treated to make luciferase and then luciferin is added to make them all glow. Each sample is then exposed to a different antibiotic until the right one works, the bacteria are killed, and the glow goes out.

In Light Sticks, a large outer tube is made of flexible, translucent plastic. Inside is a solution of oxalate ester and fluorescent dye molecules. Also inside is a smaller glass tube that contains hydrogen peroxide. When you bend the stick, the thin glass tube breaks and allows all of the chemicals to mix and react. This chemical reaction provides the energy needed by the real workers in this process, which are called electrons. It is the Light Stick chemical system that has been repackaged to also make glowing bracelets, necklaces, and earrings. So now you know a little bit about the science behind the bright lights that your parents might make you wear at outdoor sporting events, concerts and fireworks!
Submitted by Kathleen A. Carrado, Chair of the Elementary Education Committee
Reference: October 1995 issue ofChemMatters, a publication of the American Chemical Society, 1155 16th St., N.W., Washington, DC 20036.

The Fungus Among Us

Kids, our planet is made up of millions of different species which try to live together. Man is a species, just as animals like dogs, cats and fish are. Some species are so small that you can't even see them. Today you'll learn about fungus and microbes ("small life")

First, put a piece of bread and a teaspoon of water into a ziploc plastic bag, seal it, and let is sit at room temperature for 3 or 4 days. You'll notice that the bread is now covered in green mold. Mold is a furry growth of fungus found on the surfaces of decaying food or in moist, warm places. A fungus is a tiny non-flowering plant with no chlorophyll, roots, stems, or leaves. The fungus could have gotten onto the bread by a variety of means, such as transfer from your hands.

Secondly, we'll do a test for microbes that cause feet to smell bad. Feel smell bad when very tiny plants or animals grow on our skin. Have an adult boil 1/2 cup of water. Sprinkle in 4 envelopes of unflavored gelatin and dissolve it. Pour this into a clean mayonnaise jar and set it on its side (let the extra pour out and dispose of it). Put on sneakers without socks and go play outside. After about 3 hours the gelatin should be hard and your feet should be smelly. Take a swab and rub it between all your toes. Carefully brush the gelatin with the cottin tip in long strokes. Close the jar and put it in a warm dark place for 4 days.

Inside your shoes it's dark, warm, and damp. This is perfect for microbes, which will grow and grow. The mayo jar is similar, and the microbes survive by eating the gelatin. You'll see grooves in the gelatin after 4 days showing where the microbes are living and eating. If you open it, you'll smell something much worse than smelly feet. It smells really horrible. Either dispose of the jar intact or, if you want to save it, fill it with hot water and then wash with soap and water. DON'T touch inside the jar at first, and keep washing your hands.
You can collect microbes from many places, such as from the drinking fountain, the cafeteria, or even from fellow classmates at school!
Submitted by Kathleen A. Carrado, Chair of the Elementary Education Committee
Reference: The Internet at: Bill Nye, The Science Guy ( and Beakman & Jax (

The Bends

How do scuba divers get "the bends", and just what are they? Kids, you can feel some of the effects of pressure in a swimming pool. Down just a few feet underwater your ears begin to hurt. This is caused by pressure on your eardrums.

Where does that pressure come from? At the surface of the water, a column of air weighs 14.7 pounds per square inch, or "one atmosphere". When you go underwater, you add the weight of the water to the atmospheric pressure. A 10-meter (33-foot) column of water also weighs 14.7 pounds per square inch, so at a depth of 10 meters the pressure is two atmospheres: half from the water and half from the air above it. Pressure influences how divers use air. At ten meters, the increased pressure means that lungs hold twice as much air as they do at the surface - and divers breathe air from their tanks twice as fast. This is why divers can stay down only a short time, for example, 15 minutes at 50 meters.

"The bends," or decompression sickness, is a health hazard associated with pressure changes. The longer you stay down and the deeper you go, the more nitrogen gas dissolves into your body tissues. Nitrogen comes from the air we normally breathe, which is about 80% nitrogen and only 20% oxygen. If you ascend too rapidly, the dissolved nitrogen comes out of solution too quickly and forms bubbles in your tissues. You could experience severe pain in joints, dizziness, blindness, paralysis, and convulsions.

Divers learn they must ascend slowly, and sometimes take "decompression stops" on the way up. This allows the dissolved nitrogen to come out of the body safely. Sometimes a hyperbaric chamber has to be used to stabilize a diver in critical condition. These are chambers in which patients breathe 100% oxygen at greater than one atmosphere pressure using a mask. Flooding the body with pure oxygen helps to quickly and safely eliminate the nitrogen gas. Divers can also be certified to use different mixtures of air in their tanks, which are enriched in oxygen ("nitrox").
Submitted by: Kathleen A. Carrado, Chair of the Elementary Education Committee

The Internet at: (Minnesota's PBS TV station KTCA produces "Newton's Apple", a national science program for kids and adults).

It's Clay-Time

Kids, so what do you know about "clay"? Clays are layered minerals found naturally in the ground. Often the layers are much too small to see, but sometimes the minerals crystallize in big enough pieces to see them by eye. Two examples are mica and vermiculite. Did you ever peel apart the shiny, thin, transparent layers from a piece of mica? Vermiculite is very similar to mica, and observing the layers is even made easier by the high pressure steam is that often used to expand this clay into fat, swollen chunks that feel cushion-y. Your parents and teachers may have heard of vermiculite as the gold-flecked mineral added to many potting soils. It makes an excellent insulation material, and is also used as a packing material due to it's absorbency and cushioning properties. Try to find a sample at a crafts store, a nursery, or a hardware store, and peel apart the layers yourself

It is between the layers or sheets of a clay that chemistry can take place. Many molecules are soaked up into these layers and are either strongly held or else react to form different molecules. Did you know that kitty litter is almost 100% clay? The absorbent properties of clays are obvious here, and they are especially good at binding up the smelliest molecules! Clays are sold commercially as products to help clean up spills, especially oily spills. You will come into contact with kaolinite clay many times a day, for it is used as both a paper filler and paper coating. In fact, the higher quality and glossier the paper is, the more kaolinite is coating the surface; and it aids in binding the inks and dyes. Kaolinite is also the active ingredient in Kaopectate®, and so clay is even used as a dietary aid

Very pure clays can be used in a number of other products around the home. When all the iron and soil is removed, many pure clays are actually white. They are then ground into fine powders and added to many formulations. If you see "magnesium aluminum silicate" or "bentonite" or "talc" in the list of ingredients, then you know that some clay is there. It is an inert, harmless material and is used in lotions and sunscreens for example. So, besides your modeling clay and the clay in your lawn or gardens, take a look around your home and see how often you come across clays!
Written by: Kathleen A. Carrado, Chair of the Elementary Education Committee

It's Glass-Time

Kids, what does the word "glass" make you think of? Glass objects can come in all shapes, sizes, and colors. List all the objects you come across in one day that are made out of glass. Where does glass come from? One example is window glass, also called "soda lime" glass. It is made mostly from a pure, white sand called silica. Also added are soda (soda ash or sodium carbonate) and lime (limestone or calcium carbonate). Soda ash makes the sand melt more easily and lime makes the glass hard and waterproof. In a glass factory furnace, the mixture is heated to 2,500°F for up to a day. Molten glass is viscous and small bubbles take a long time to disappear. To visualize this, mix powdered sugar in a glass of corn syrup and watch how long it takes for the bubbles to rise.

What different kinds of glass are there? Huge windows are called float glass because of the way they are made. Since they need to be perfectly flat and smooth, the molten glass is floated on a layer of molten metal (often zinc) and is then cooled very slowly. To visualize this, pour some cooking oil over the back of a spoon onto water in a clear bowl. See how the oil layer floats on top? Some other types of glass are made from other ingredients added to the silica. "Pyrex" cookware is borosilicate, made with some boron to withstand quick temperature changes. Lead crystal incorporates lead to sparkle and make the glass easy to cut and engrave.

What do you know about glass recycling? Amber and green glass are separated because a coloring agent has been added that cannot be removed. Therefore, brown bottles can only make other brown bottles. Recycled glass is crushed into pieces called cullet. Cullet, which melts at a lower temperature, is mixed with the raw materials silica, soda, and lime. This process reduces air pollution by 20%, water pollution by 50%, and saves space in landfills. However, only about 10% of the glass used in the U.S. is recycled.
Written by: Kathleen A. Carrado, Chair of the Elementary Education Committee.

References: "Glass" by Jane Chandler and the "Newton's Apple" web page:

Updated 2/12/99