We've chronicled the fun you can have with dropping Mentos candies into two-liter bottles of Diet Coke. Now students at Appalachian State University in Boone, North Carolina, have done the testing to tell us why this is really so much fun. Their conclusions are not the conventional wisdom that was first thrown out there when people started this fun experiments.
It's all over the Internet. It's on David Letterman and the Today Show. It's on NPR, for Pete's sake. Across the country, people are caught up in a frenzy of extreme Diet Coke and Mentos experiments.
Get permission, go outside, and have a hose handy. Things are gonna get messy...
Of course, you don't have to use Mentos and Diet Coke. The good folks at EepyBird.com have done many, many experiments, and it turns out that dropping just about anything into any kind of soda creates at least a little fizz. But Mentos and Diet Coke is an especially satisfying combination.
So how does it work?
The explosive effect is caused when the carbon dioxide that's been compressed in the soda escapes so quickly that the pressure pushes the soda out of the bottle. That's the easy part. But why do Mentos, in particular, cause such a good effect?
Part of the answer has to do with nucleation sites. "Huh?" you ask. Yeah, me, too. Soda is a liquid supersaturated with carbon dioxide gas, and nucleation sites are places where the carbon dioxide can make bubbles. A nucleation site can be a scratch on a surface, a speck of dust, or any place where you have a high surface area relative to volume.
Bubbles in soda: (Photo courtesy Spiff, Wikipedia Commons)Courtesy Spiff
And Mentos have a lot of nucleation sites. There are lots of imperfections in their surfaces, and that allows lots and lots of bubbles to form. Plus, Mentos are heavy enough to sink when you drop them in, so they react to with the soda all the way to the bottom of the container. The sticky result is a fun, foaming mess.
But what happens if you drink Diet Coke and eat Mentos at the same time?
The EepyBird website has the answer, if you really must know...
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