Totally Blowing Shit Up Tuesdays: Because You Demanded It

Unlike most radio stations in this country, which feature a boring glut of mediocre pre-programmed tripe, I'm willing to take requests. So, today's episode is brought to you by the letter C, as in, Mr. Condescending. He asked for it, and since I'm a whore for my readers, I'm obliging.

So, today we're going to explore the wonders of the Diet Coke and Mentos Eruption.

I'm sure you've all seen the episode of Mythbusters where Adam and Jamie were certain that some form of internet legerdemain was at work during the infamous Diet Coke/Mentos fountain symphony that started the whole craze in the first place. Of course, the idiots boys were proved wrong, and then they tried their best to get to the bottom of why this thing goes off like it does.

My first guess was that it was an acid/base reaction, the base coming from the Mentos (I was guessing some kind of preservative) and the acid being the carbonic acid dissolved in most sodas to give it fizz. Carbonic acid is basically the bastard child of water and carbon dioxide, and it's decomposition reaction looks like this:

H2CO3 -----> H2O + CO2

The problem is that it's not a chemical reaction at play here. Instead, as Adam and Jamie proposed, it's simply a matter of physics. They postulated that the tiny pits, grooves and swirls on the surface of the Mentos helped form tiny bubbles so quickly that they erupted in a fountain of Diet Coke. In a paper published in New Scientist of June from last year, a physicist from Applachian State University here in lovely North By God Carolina unraveled the mystery of the Diet Coke fountain.

Seems as though it's simply a matter of gravity, surface tension and the aforementioned nucleation sites on the surface of candies. The aspartame (the artificial sweetener) dissolved in the Diet Coke is perfect for breaking up the interactions between the water molecules making them more willing to give up the goods. The same trick works with college chicks and alcohol. The surface of the Mentos, which is covered with gum arabic, helps to make tiny bubbles quickly, and the specific gravity of the Mentos helps them to sink to the bottom of bottle, exposing themselves to more Diet Coke. Crushed up Mentos, despite their higher surface area, don't sink as quickly and therefore don't work as well.

That's a fancy way of saying that Diet Coke + Mentos = Fountains of Wayne Awesome.


Now, if you give a man a fish, he'll eat for a day. If you teach him to fish, you've just lost yourself a fish junky that will pay you for what you catch. In the same vein, if you give a man some candies and a bottle of diet cola, he'll make a fountain. If you give a man a cap along with those candies and diet soda, he'll make a rocket. Robert Goddard would be so proud.


Well...he probably wouldn't have been proud of that guy.

As Scope pointed out last week, it's all fun and games until one of these rockets goes flying through the window of your house or your windshield...or your abdomen... Then things might not be nearly as funny. Well, at least not for you, but the rest of us will sure point and laugh at your misfortune. So, should you decide to try making your own amateur rockets, do it in a wide open area, alright?

Sadly, I have been proven wrong. Studies of the pH of the Diet Coke before and after the fountain have shown that the pH (measurement of the acidity of a solution) does not change, so the reaction has nothing to do with acid/base chemistry. Dammit! I hate being wrong, but I'm man enough to admit when I'm wrong...just not to my wife.

Good thing I didn't tell her that it was an acid/base reaction. Ever. *whistles innocently* I'll be out back with some Diet Coke and fresh-makers if you need me.