Stories tagged nucleation sites


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.

Want to try it at home?

Get permission, go outside, and have a hose handy. Things are gonna get messy...

  1. The simplest thing is to just drop a Mentos or two into a small bottle of Diet Coke.
  2. Not so satisfying? OK, now it's time to get serious.
  3. Make a "cartridge" of Mentos. Hold each candy with a pair of pliers, and carefully drill a small hole through the center. Then string five or six Mentos onto a straightened paper clip or a piece of fishing line.
  4. Hold the bottle cap with a pair of pliers and drill a hole through the top. (Start with a hole 1/4" in diameter.) Thread the paper clip or fishing line with the Mentos cartridge through the bottle cap so that the candy will hang down inside the bottle when you screw on the cap. Different sized holes in the cap will yield different effects.
  5. You can also carefully drill holes in the bottle, above the level of the soda. If you drill a ring of holes, you get a pretty neat effect. And you'll also make a super big mess.

Of course, you don't have to use Mentos and Diet Coke. The good folks at 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)
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...