DANCING RAISINS

by

John Scavo

This lesson was created as a part of the SMART website and is hosted by the Illinois Institute of Technology

Dancing raisins, mothballs, and other variations:

Basic mothball and raisin theory -

A truly silly trick if you happen to have some mothballs.  Mostly fill a glass jar with water.  Add a little vinegar - 1/4 to 1/3 cup (60 ml) - add 2 tsp. (10 ml) of baking soda.  Stir gently.  Add a few mothballs.  As long as their surfaces stay fairly rough, they should begin to bounce up and down.  This will also work quite well using clear soda water with the mothballs.

Raisins and alka-seltzer or clear soda will perform the same way.  The irregular surfaces on the mothballs or raisins hold some of the carbon dioxide bubbles.  When enough bubbles accumulate to lift the weight of the mothball (or raisin), it rises to the surface.  Some of the air bubbles escape into the atmosphere, and the mothball/raisin, which is denser than the water or soda, sinks to the bottom to start the cycle over again.  The effect will last longer if the container is sealed, as less carbon dioxide will be able to escape.

There are quite a few other small objects that will work.  The key is that these objects be able to trap air bubbles on their surface and that they are light enough to be buoyed to the surface by the bubbles, and that they won't dissolve in the liquid.

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Fun with champagne:

If you happen to be drinking champagne or a sparkling wine, the raisins will bounce in the glass for a very long time.  Of course,  very few of those who enjoy a glass of champagne will have the patience or will power to not drink the experiment.

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Even more fun with gelatin:

If you pour lemon-lime soda into a clear glass cup, add some salt to the soda and put some Jell-O into the cup, that after a while, the Jell-O will bounce up and down inside of the cup as air bubbles accumulate and come off of the Jell-O.

Zero to Einstein in 60 seconds, The Wild Goose Company, pp. 14-16.

http://www.ed.gov/pubs/parents/Science/soap.html

http://www.amasci.com

http://clubs.yahoo.com/clubs/scienceconnection

Back to John's lesson on how to make a thermometer.