Why did only one bottle of water freeze?
January 4, 2010 11:27 AM   Subscribe

Why did only one bottle of water freeze?

I left two 20 oz. plastic bottles of water in my car overnight, right next to each other in the cup holders. One froze solid, the other remained entirely liquid. The one that froze was Dasani brand, and the bottle was 3/4 of the way full. The one that remained liquid was Aquafina, and was 2/3 of the way full. How is this possible? I know Dasani puts sodium in their water, but wouldn't that make it take longer to freeze?
posted by amro to Science & Nature (19 answers total) 9 users marked this as a favorite
Interesting. Maybe the plastic is thicker on one of the bottles?
posted by kdern at 11:32 AM on January 4, 2010

Were both caps on equally tight? I often have a bottle in my car that I think should have frozen, but doesn't. Once I crack the top, it becomes insta-slush-ice-chunks. Something to do with the pressure change I imagine.
posted by sanka at 11:38 AM on January 4, 2010

Best answer: If one of the bottles contained significantly purer water than the other, the purer water might have supercooled (thanks, AskMe)---but it didnt' freeze due to lack of nucleation sites (or something).
posted by leahwrenn at 11:44 AM on January 4, 2010

Was one bottle in the sunlight more than the other? Variable solar heating might have a bearing on this.
posted by pjern at 11:50 AM on January 4, 2010

Best answer: My bet is on supercooling. The same thing happened to me on Christmas -- two identical bottles of water in the car, freezing temperatures. One froze, one didn't.

...and then the one that did not freeze suddenly froze solid in the space of a second or so, when a tiny ice crystal on the lid fell into the water. I saw it happen, and it was faaantastic.

I'm serious, it was one of the neatest things I've ever held in my hand; a shockwave-of-freezing racing through the water.

If your bottles are still below freezing, see if you can make the liquid one freeze. You'll thank me.
posted by aramaic at 11:51 AM on January 4, 2010 [10 favorites]

Response by poster: aramaic, I am definitely going to try that.
posted by amro at 11:55 AM on January 4, 2010

I'll toss in that the variance can also be partially explained by the different shapes of of the bottles -- for example, Dasani has a thinner neck, and Aquafina has ridges -- and their different volumes of water.
posted by Cool Papa Bell at 11:57 AM on January 4, 2010

Here you go.
posted by weapons-grade pandemonium at 12:03 PM on January 4, 2010 [2 favorites]

I found that Gatorade would always supercool in my freezer.
posted by delmoi at 12:35 PM on January 4, 2010

Its even better if you open the top carefully and try to drink it. You can feel the ice forming in your mouth.
posted by Iax at 1:13 PM on January 4, 2010

is there any way to replicate this experiment intentionally? just put pure water in freezer or.... what?
posted by DetonatedManiac at 1:13 PM on January 4, 2010

Salts in the water don't increase the time it takes for it to freeze (directly), it only lowers the temperature at which it will freeze.

The bottle could have been supercooled, but my money is on something far less sexy. Sunlight, radio clock keeping it warmer, cell phone charger nearby keeping it warmer. Something like that.
posted by gjc at 1:46 PM on January 4, 2010

is there any way to replicate this experiment intentionally? just put pure water in freezer or.... what?

W-G P's first link says yes, basically. Apparently get pure water (not all bottled water is pure enough, apparently FIJI is though) and stick it in the freezer. Take it out the next day and shake it a little. Looks like it took a few tries to work.
posted by Solon and Thanks at 3:11 PM on January 4, 2010

Part of the answer might be microclimate. Once the Dasani bottle started freezing first (whatever the reason), the temperature of that bottle stayed at 32F until it finished freezing (see "enthalpy of fusion/freezing), which helped keep the local temp, including the temp around the Aquafina bottle, from dropping as quickly.
posted by Good Brain at 3:18 PM on January 4, 2010

Our office water filter + old crystal geyser bottle + office freezer gives me a pretty good chance of supercooled water, so water in freezer plus luck seems like a good way of managing it. Eventually the water will just freeze, though, so you have to get the timing right, as well.
posted by that girl at 4:37 PM on January 4, 2010

This is not some practical joke!
posted by mdonley at 5:09 PM on January 4, 2010

Absolutely a supercooling thing and it happens to me all the time. Every night I put a 2L bottle of pop in the freezer (or outside in the winter). About 3 mornings out of 7, when I pull it out it seems to be entirely liquid. But if you crack the lid and give the bottle a sharp rap, it suddenly freezes. (Not solid, but very thick slush. Also, rip the label off before you start it so you can watch all the way down the bottle.) It never gets old. Try it.

Sometimes I'll see this with flav-r-ice as well. Put a whole roll into the freezer and in the morning about half of them will be frozen and the others not. Flick the not-frozen ones to watch it freeze in real time.
posted by DU at 7:17 PM on January 4, 2010

I just want to say, because of this thread I spent an hour last night just watching supercooling videos on YouTube. That is some crazy cool science right there.
posted by Billegible at 11:28 AM on January 5, 2010

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