The Mentos and Diet Coke reaction creates a foamy geyser due to a physical reaction where the rough surface of the candy provides nucleation sites for carbon dioxide bubbles in the soda to rapidly form and escape, forcing the liquid out in a powerful eruption, with Diet Coke preferred for being less sticky. To do it, drop several Mentos into a 2-liter bottle of room-temperature Diet Coke and quickly step back, letting the candy's surface and quick drop speed up the release of trapped CO2 gas. Then you see the eruption!
Key Components of the Experiment:
Why Diet Coke? While any carbonated drink works, Diet Coke is preferred because it is less sticky to clean up and contains aspartame, which acts as a better surface-tension reducer.
Why Mentos? The surface of a Mentos candy is covered in thousands of tiny pits (nucleation sites) that allow the carbon dioxide in the soda to form bubbles rapidly.
The Reaction: The candies sink to the bottom, creating a massive amount of bubbles that quickly rise and force the liquid out, often creating a geyser up to 13 feet high.
After watching an episode of Mythbusters, I learned I had to try this at home. So, of course I've done this experiment many times with my kids over the years. You can actually buy a STEM kit on Amazon to do this with your kids or on your own. Next time you have a group of friends over try it out. An eruption of fun will happen. Check out the video below:
And while you are playing with science at home, here are 5 more cool things to try at home courtesy of Mark Rober. If you have never watched Mark before, check out his YouTube channel. Some very cool stuff.
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