Okay, this one’s just creepy. I posted the Mentos / Diet Coke thing yesterday. Today, I awake to find that JM O’Donnell, over at Immunoblogging has posted this, two days earlier.

Not only had I not seen his post, I hadn’t even seen this video until last night, when a commenter left a link to it on yesterday’s post… Someone should investigate the possibility that we were twins, separated at birth. There could be a huge conspiracy going on.

Still, either Ocellated or Immunoblogging needs to go back to elementary school for a refresher on the rudimentary principles of math. Everyone’s family with the commutative property of addition, yes?

Adding 1 + 2, is the same as adding 2 + 1.

Well, in my case, Mentos + Diet Coke = Fun. But when Mr. O’Donnell does the math, he gets Diet Coke + Mentos = Awesome. Someone is clearly wrong.

What do you get when you take The Fresh Maker ® and The Real Thing ® and put them together?

My wife and I heard about this recently on the popular show Myth Busters, and after seeing it, we had to try it out.

Lucky for me, I had a professor that needed a 3 liter bottle. After stopping at four different stores to secure a package of Mentos, the experiment was ready. A biology party was the perfect setting.

So what does it look like?

Here’s a closeup of that same shot:

Also, I’ve added a series of photos in the gallery showing the progression as the eruption occurred. The whole thing is extremely fast. It’s over within one to two seconds.

So how does it work?

Upon adding three or four Mentos to the Diet Coke, what happens is that virtually all of the carbon dioxide is released from the Diet Coke in an extremely short amount of time. The resulting pressure forces the liquid out of the bottle with surprising force, resulting in the geyser.

More specifically, the tiny holes on the surface of the Mentos serve as a nucleation site, facilitating the rapid formation and release of tiny bubbles of CO2.

Wikipedia has an article on the subject, with more detailed information on the science behind it.

It’s fun, it’s cheap, you should try it. Just not inside.