2008-04-17

Irony Redux

The day that I canceled-my-credit-cards-just-hours-before-my-wallet-was-returned had even more ironic surprises for me. That morning, out of concern for the lost wallet and identity theft (or at least having to explain to some credit card company employee that I did not, in fact, buy a go cart, a goat, 20 inch rims for my Honda, or whatever it is that identity thieves buy), I woke up early, earlier than that night's sleep should have allowed. Given my fatigue, I threw a warm can of Dr. Pepper from the pantry into the freezer's ice bin. The goal was rapid cooling, so that when I left for work, the can would be prepped for the mid-commute consumption. I was well aware of the potential consequences.

In case you have never frozen your favorite canned and carbonated beverage, let me explain the physics* involved. First Fact: Water is magic. It expands when it freezes. This expansion is what makes ice float. Second Fact: The main ingredient of any soft drink is water. Q.E.D: when you freeze a can of soda, the can will expand. Since the contents are already under the pressure of carbonation...viola, the can may well explode in an icy inferno.

I know this. I've done this. I've gleefully watched it happen to the unsuspecting. I specifically told myself, when I put the can in the freezer, that I needed to remove it before I left for work, or the consequences would be dire.

Imagine my shock and self loathing, then, when I was greeted with the following site when I returned home that night:

Yes, gentle reader. I am an idiot. What you see is indeed frozen Dr. Pepper sprayed everywhere. And I mean EVERY-WHERE: in the gears of the ice maker, all over the frozen vegetables, and the ice cream in the door. As you can see, the poor ice maker took the brunt of it.

And this is what happened to the can:

To be honest, the whole situation was so hilarious that I couldn't even be mad, even though it took probably half an hour to chisel frozen soft drink from my freezer walls. Why wasn't I mad? First: I knew better, and remembered that I knew better, but forgot anyway. And second, how can you be mad at physics? The outcome was inevitable. It's like being mad at gravity. There's no point. And, look at what happened to the can! Isn't that COOL?



*Yes, I oversimplified. If you can endure some nerdiness, here's some thought into exactly what happened with the can.

WARNING: SCIENCE FOLLOWS

At first, I was surprised that the can exploded quite so violently and stuck to the walls. I mean, if you freeze a bottle of water, it doesn't explode, it just distends. The key, I think, lies in the combination of sweeteners and carbonation in the soda. The sweeteners lower the freezing point of the water, just like anti-freeze. This means that the can must cool below 32 degrees before much expansion will occur. Most freezers are at 0 F or colder, so no big deal there. What this means, though, is that the liquid is super cold when the can ruptures. When the can finally does rupture from expansion, the carbon dioxide that is dissolved in the water (the carbonation) quickly "boils" out of the water. The CO2 is very anxious to escape because of the additional pressure of expansion. It is this rapid release of gas that sprays the soda everywhere. Finally, as the C02 evaporates, it takes energy with it, leaving the soda even colder than it was in the can. This means that the soda hits the freezer walls as a nearly frozen slush, explaining the artful and rock hard Dr. Pepper all over the freezer.