Bouncing Raisins
Adapted from National Geographic

Here's a sweet way to investigate the action of an important greenhouse gas--CO2

You will need:

• 4 tablespoons of vinegar
• 3 tablespoons of baking soda
• A tall clear glass or jar
• Enough water to fill the glass or jar halfway
• 8 or more raisins
• Measuring spoons

What to do:

1. Fill the glass or jar halfway with water.
2. Add the vinegar and baking soda to the water. The mixture will begin to fizz.
3. Drop the raisins one at a time into the mixture. The raisins may sink at first. Soon they will rise to the surface then sink, then rise again. The raisins will continue to "bounce" for at least an hour.

What happened?

Combining vinegar and baking soda creates bubbles of carbon dioxide (C02), the same gas that's in carbonated soda. Bubbles collect on the raisins and lift them up. At the surface the bubbles escape, the raisins sink, and the process begins again.