Dancing Raisins

This is a fun experiment to learn about density and the influence of carbon dioxide on naturally denser things.

Materials:

• A tall glass cup or jar
• A can of colorless soda (like Sierra Mist or 7Up)
• A handful of raisins 

Directions:

• Pour the soda into the glass or jar. You will see bubbles coming up from the bottom. Those are carbon dioxide bubbles released by the liquid (they were put there to make the soda bubbly)
• Drop 8-10 raisins in the container. Watch what happens. Do they drop to the bottom immediately? Then what happens?
• You can try this experiment with other things in the house, to see if you get different results.

What happens:  Initially, the density of the raisins is higher than the liquid they are placed in. So they sink right away. But the bumpy skin of the raisin is the perfect place for some of those tiny air bubbles of carbon dioxide to cling to the raisin. When enough of them collect on the outside of the raisin, the bubbles carry the raisin to the top. The bubbles then pop and escape into the air on the surface, and the raisin will drop to the bottom again. This happens over and over until the soda goes flat and there are not enough bubbles to carry the raisin up again.