SODA GEYSER
This doable is sticky and funny and marvelous to watch! It is easy to do, but for the best effect you need to have the right ingredients:
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A 2 liter bottle of diet Coke, which must be at room temperature
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At least 6 Mint Mentos (the breath-mint chewy candies).
Other preparations:
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Find an outdoor spot where it will be easy to hose off the table (if you use one), the ground, and possibly yourselves
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Swim goggles or other protective eye gear would be smart to wear for anyone participating.
Watch this video first because it will show you what you need to do and what to expect:
https://www.youtube.com/watch?v=ZwyMcV9emmc (2:20)
Steps:
1. Because we didn’t have any test tubes handy, we made our own heavy paper tube by wrapping the paper around the Mentos’ roll and taping it. Then we loaded it with 6 Mentos, using the rest of the still-wrapped Mentos roll as a plug and pusher at the other end.
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2. We cut a piece of light cardboard to the size of a credit card to slide between the bottle top and our tube of Mentos, as they did in the video.
3. Then we went to a spot outside on the grass to try it out. And it worked!
A few years ago people put together spectacular displays of carefully timed soda geysers. This video, with the two guys kitted out in lab coats and safety goggles and timing their display to music, is one of our favorites:
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https://www.youtube.com/watch?v=hKoB0MHVBvM (2:58)
How does this work? Interestingly, it is a physical rather than a chemical reaction.
Bubbles are carbon dioxide gas, which soda companies put into drinks to make the liquid fizzy. Mentos are covered with tiny imperfections – bumps and pits and scratches that you cannot see without a microscope. The carbon dioxide molecules collect in and on these places on the Mentos and form bubbles that quickly rise to the surface.
So the geyser isn’t caused by the soda and candy mixing their contents. In fact, the Mentos will still be pretty much whole after the geyser has finished, and sitting at the bottom of the soda bottle.
And if you want to see a real geyser in action, check out these videos about Old Faithful in Yellowstone National Park:
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https://www.youtube.com/watch?v=4mZY7uxb7Gc (Video of its eruption, 2:36)
https://www.youtube.com/watch?v=6zp3SwzpDvU (The geology of Old Faithful, 8:11)