Gitter Globe

45 minutes
What do I need?
 Girl preparing ingredients

 

  • Rubbing (isopropyl) alcohol
  • Vegetable oil
  • A plastic container or glass jar with an interesting shape (long, skinny olive jars and the fancy jars that hold some marmalades, jams, or jellies work well)
  • Small beads, sequins, glitter, or other tiny, shiny things
  • Food coloring (if you want)
  • Clear tape (if you want)

What do I do?

1 Fill about 1/4 of the jar with rubbing alcohol. Add a drop of food coloring.

 DANGER!

Don't forget to be careful with glass.
2 Pour vegetable oil into the jar. Leave about 1/2 an inch of air at the top of the jar. Let the globs of oil settle. Is the oil on top of the alcohol or underneath it?

 

3Drop tiny, shiny things into the jar. Use as many as you want. Don't use anything too heavy-like a marble-that might break the jar when you shake it.


 4 When all the tiny things are in the jar, carefully pour in more oil until the jar is completely full-right up to the rim.

5 Screw the lid of the jar on very tightly. (If you want, you can tape around the lid to make sure it won't leak.)

6 Gently shake the jar. The oil and alcohol will mix and turn a milky color, and the beads and glitter will float and spin.

Adding Ingredients

7 Let the oil settle again. That will take about 5 or 10 minutes. Now spin the jar instead of shaking it. What happens?

 What's Going On?

Why doesn't the oil float on top of the alcohol?

Since oil floats on top of water, you might have thought that oil would float on top of alcohol, too. But the oil sinks to the bottom and the alcohol floats on top of the oil. Even though water and alcohol are both clear liquids, they have different densities. Alcohol floats on top of oil because a drop of alcohol is lighter than a drop of oil the same size.

Why don't oil and alcohol mix? For that matter, why don't oil and water mix?

The answers to these questions have to do with the molecules that make up oil, water, and alcohol. Molecules are made up of atoms, and atoms are made up of positively charged protons, negatively charged electrons, and uncharged neutrons.

Cartoon MoleculesThe atoms that make up water molecules and alcohol molecules are arranged so that there is more positive charge in one part of the molecule and more negative charge in another part of the molecule. Molecules like this are called polar molecules.

The charged particles in an oil molecule are distributed more or less evenly throughout the molecule. Molecules like this are called nonpolar molecules.

Polar molecules like to stick together. That's because positive charges attract negative charges. So the positive part of a polar molecule attracts the negative part of another polar molecule, and the two molecules tend to stay together. When you try to mix water and oil or alcohol and oil, the polar molecules stick together, keeping the oil molecules from getting between them-and the two don't mix. When you try to mix water and alcohol, they mix fine, since both are made of polar molecules.

What's this pretty toy doing in a set of science experiments? It seems more like an art project to me.

When you make a Glitter Globe, you're experimenting with two liquids that won't mix with each other--alcohol and oil. Playing with the Glitter Globe gives you a chance to watch how liquids flow. And in the process, you make something that's pretty.

Some people think that science and art have very little in common. At the Exploratorium, we disagree. Both artists and scientists start their work by noticing something interesting or unusual in the world around them. Both artists and scientists experiment with the things they have noticed. Art and science begin in the same place-with noticing and experimenting.


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This and dozens of other cool activities are included in the Exploratorium's Science Explorer books, available for purchase from our online store.

About the Books

Published by Owl Books,
Henry Holt & Company, New York,
1996 & 1997

ISBN 0-B050-4536 & ISBN 0-8050-4537-6,
$12.95 each






© 1998 Exploratorium