How kids create toys with chemistry at home

(First in 2-part Series)

(Editors note: Each fall, the St. Louis section of the American Chemical Society (ACS) sponsors a Chemistry Exposition at the Saint Louis Science Center. A lot of the exposition content is aimed at kids. Local scientists help kids to understand how chemistry influences their world.

(Last year, the kids' part of the exposition was called "The Joys of Toys." Included were experiments kids could do at home. At the 2006 exposition, the kids' portion will deal with chemistry in your home.

(In this 2-part series, Young Saint Louis.com will list some experiments you can do at home. This first article deals with toys. The second in October will deal with chemistry in your home. Also in October, YSL.com will preview activities scheduled for the 2006 Chemistry Exposition at the Science Center Saturday, Oct. 21. Plan to attend; it'll make science real for you today.)

(We'll also introduce you to ACS's neat website which includes kids features all year.)

Games played with balls have been around for thousands of years. But, in those early years, the balls were made of rock or wood.

Imagine Cardinal slugger Albert Pujols trying to hit a 350-foot home run if the ball and bat were both made of wood.

Discovery of natural rubber changed the character of balls and the games being played. And then other materials made it possible for balls to be both hollow and solid.

Finally, chemistry came along to make it possible for kids to make a bouncing ball at home, using common household products. Also, we'll have experiments that help you make lightning and a homemade lava lamp.

The American Chemistry Society urges kids to do all these experiments with a parent or other adult in attendance.

Meg A. Mole's Bouncing Ball

Materials:

Procedure:

Where's the Chemistry?

A polymer is a very long chemical made up of repeating little chemical units all hooked together in a very long chain. Glue contains a polymer called polyvinyl acetate (PVA). When you add borax solution to polymers like PVA, it crosses or connects the two polymers together like a net or a spider's web.

Depending on how much of each ingredient that you mix together, you can make something that is "goopy," slimy or stretchy. For instance, if you add more cornstarch, you will be able to bend and stretch the mix. Add less borax and you will get a "goopy" mixture. To make a slimy substance, add more glue.

Making Your Own Lightning

Supplies:

Instructions:

What causes the spark? How does this relate to lightning?

What's making the sparks?

Let's start with some vocabulary:

When you rub the Styrofoam tray on your head, electrons from your hair pile up on the tray. When you put the pin tin on the Styrofoam tray, the free electrons in the aluminum pie tin move as far away from the electrons on the Styrofoam as they can. When you touch your finger to the pie tin, the free electrons jump to your hand, making a spark.

After the electrons move to your hand, the aluminum in the pie tin is short of electrons. When you lift it off the Styrofoam and touch it, the free electronics jump back to the aluminum, making another spark.

How does this relate to lightning?

Lightning is seen when a stream of moving electrons run between a cloud and the ground, or between two clouds. It's just like the electrons jumping from the pie plate to your finger, only on a much larger scale.

Homemade Lava Lamp

Supplies:

Instructions:

Why does the oil float on top of the water?
What happens when the salt is poured in?
How does this relate to what happens in a lava lamp?

What causes all the action?

The oil floats on top of the water because a drop of oil is lighter than a drop of water of the same size. The scientific way of saying this is that water is denser than oil. Density is a measurement of how much a given volume of something weighs. In addition to having different densities, oil and water are also known as immiscible liquids. Immiscible means they don't mix.

Pouring salt on the oil and water mixture causes lots of movement. Salt is denser than water and oil so it sinks to the bottom. As the salt passes through the oil layer, a blob of oil ticks to it and travels with it to the bottom. As the grain of alt dissolves, it releases the oil, which floats back to the top.

How does this relate to a lava lamp?

The lava in a lava lamp is a special kind of wax. The wax doesn't mix with the liquid that surrounds it. When the wax is cool, it is denser than the liquid so it stays on the bottom. The light in the lamp is located at the base where it gives off heat. The light warms the wax that is resting on the bottom. As it warms up, the wax expands. The weight of the wax remains the same but it takes up more space. In other words it becomes less dense. The warmed up wax is less dense than the liquid so it rises to the top. At the top of the lamp, it cools off, becomes denser and then sinks to the bottom where the process repeats itself.

Final Note: If like to learn more about chemistry, you can go the ACS's website which is at www.chemistry.org. The special sections for kids are labeled "Kids" and "Wondernet." The website is updated periodically, so you'll find new stuff all through the year.

(In October edition: Experiments about things in your home.)