Tuesday, April 21, 2009

Chemistry - pt 4 Errupting Volcano

Chemical volcanos are classic projects for science fairs and chemistry demonstrations. The mentos and diet soda eruption is really powerful, capable of producing jets of soda several feet high. It's messy, so you might want to do this project outdoors. Our class went to an open field with our directions in hand and proceeded to do our volcano experiment. The children really had a lot of fun. To achieve similar results, here's what you need to do:

  1. First, gather your supplies.
  2. You could substitute normal soda for diet soda. The project will work just as well, but the resulting eruption will be sticky. Whatever you use, the drink has to be carbonated!
  3. First, stack the candies. The easiest way to do this is to stack them in a test tube narrow enough to form a single column. Otherwise, you can roll a sheet of paper into a tube just barely wide enough for a stack of candies.
  4. Place an index card over the opening of the test tube or end of the paper tube to hold the candies in the container. Invert the test tube.
  5. Open your full 2-liter or 16 oz bottle of diet soda. The eruption happens very quickly, so set things up: you want the open bottle - index card - roll of candies so that as soon as you remove the index card, the candies will drop smoothly into the bottle.
  6. When you're ready, do it! You can repeat the eruption with the same bottle and another stack of candies. Have fun!

What You Need:

  • roll of mentos candies
  • 2-liter bottle of diet soda
  • index card
  • test tube or sheet of paper

Why does it work? The caffeine, potassium benzoate, aspartame, and CO2 gas contained in the Diet Coke and the gelatin and gum arabic ingredients of the Mentos all contribute to the jet effect. The surface of the mint Mentos is littered with many small holes, allowing CO2 bubbles to form very rapidly and in great quantity, in turn causing the jet of foam. (Courtesy of wikipedia)

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