froze and thawed a bottle of coca cola. now half of the content is missing. is all that just the carbonation?

September 17, 2010 2:17 PM

froze and thawed a bottle of coca cola. now half of the content is missing. is all that just the carbonation?

I unintentionally left a 1L plastic bottle of coca cola on its side in my freezer. it was unopened and sealed and when I discovered it frozen solid it was utterly wet from the outside. I put it back into my fridge and basically let it slowly thaw from the solid chunk of ice that it was over the next few days.

I just looked at it again and now the still sealed cola is nearly half empty. I'm surprised at how much is missing in spite of the bottle still being factory-sealed and my curiosity prompts me to ask you guys what happened.

I take it the fizz went out but is it really that much? or do these plastic caps expand and the wet fluid on the outside of the bottle wasn't just regular freezer ice but coca cola? or aren't the caps all that good to begin with? I already know the coke will be flat and that there's probably some connection but I don't quite know how exactly this happened.

any 6th grade physics teachers want to enlighten me?

(thanks.)

posted by krautland to science & nature (15 answers total)

I would assume that as the liquid froze and expanded the bottle cracked and a bunch leaked out when it thawed. This would seem to be immediately obvious though, as there would likely be a big sticky puddle of cola underneath the bottle in your fridge. Is the bottle intact with no small cracks anywhere? If so, I've got no clue.
posted by Jawn at 2:23 PM on September 17, 2010

Cola is mostly water; which expands in volume by about 9% as it freezes. As this happened, it would have broken the seal on the bottle, and then about half the cola managed to leak out before freezing solid. (So you are right, the wetness was probably cola.)
posted by mbrubeck at 2:24 PM on September 17, 2010

Yeah it leaked out. I froze a can of Coke once and it was all there once I'd thawed it and opened the can, but a metal can can (ha!) expand and change shape under pressure better than a plastic bottle.
posted by EndsOfInvention at 2:30 PM on September 17, 2010

I just opened the bottle and it wasn't all that flat. what seems to have happened though is that it's no longer sweet. it tastes thin, as if the sugar has disappeared.

no puddle of cola anywhere. I checked.
posted by krautland at 2:52 PM on September 17, 2010

It leaked and it went somewhere. Check your drain pan under the fridge, before it draws ant/flies.
posted by cosmicbandito at 2:56 PM on September 17, 2010 [2 favorites]

As we know from drinking Slurpees as kids, when the water freezes, the sugary syrup doesn't. So what leaked out was mostly syrup.

The carbon dioxide is dissolved in the water and thus doesn't change its volume. I think.

Many commercial ice creams (and soft-serv for sure) does have air in it to make it easier to scoop and a bit lighter on the palate. And possibly cheaper.
posted by gjc at 2:59 PM on September 17, 2010 [1 favorite]

Water expands almost 10% when it freezes, with a pretty incredible amount of force. The air space in the top of a two liter is less than 200 mL. Either the plastic deformed dramatically or the seal broke and the still-liquid syrup leaked, as gjc pointed out.
posted by supercres at 3:21 PM on September 17, 2010

Also possible that the bottle has expanded in not-so-obvious ways. Some bottles are designed to do this instead of exploding. I doubt they would double in volume though.
posted by chairface at 3:25 PM on September 17, 2010

but a metal can can (ha!) expand and change shape under pressure better than a plastic bottle

Really? I accidentally did that once, trying to cool it down quickly and forgot about it- it blew up. My flatmates gave me hell about it :D
posted by malusmoriendumest at 3:29 PM on September 17, 2010 [1 favorite]

it tastes thin, as if the sugar has disappeared.

As it freezes, the sugar tends to collect in the still-liquid part, and the frozen part tends to have little sugar in it. The liquid, bearing most of the sugar, leaked out, while the frozen part, with little to no sugar, stayed in the bottle. (Aside: this is deliberately done in the making of ice wine: grapes are left on the vine through the first frost, and they partially freeze, leaving a super-sweetened liquid grape juice to be extracted and then fermented.)
posted by DevilsAdvocate at 3:44 PM on September 17, 2010 [4 favorites]

As it freezes, the sugar tends to collect in the still-liquid part, and the frozen part tends to have little sugar in it.

Yep, this same idea is how they make ice beer. Freeze it, the water freezes first, what's left behind is more concentrated beer with a higher alcoholic content.
posted by chrisamiller at 4:18 PM on September 17, 2010

The increase in pressure forced CO2 out of the seal (which still retained the liquid). Flat soda has less volume than soda inflated with dissolved CO2. Carbonation and acidity effect taste.
http://www.science-house.org/CO2/activities/co2/soda.html
posted by llc at 9:04 PM on September 17, 2010

If you are experimenting with future bottles, try opening after cooling but before the pressure breaks the seal. You can then open it and watch it freeze in seconds

My siblings and I discovered this as kids. Mom would leave bottles of sparking water outside to chill them during winter. One time we brought one in it seemed far more pressurized than normal (could barely squeeze it) and when opened there was a riot of fizzing and ice. Of course we then raced out to try the rest. When my mom objected to the destruction of her entire sparkling water supply, we shouted "But Mom this is SCIENCE!" and we were granted funding to run the remaining 11 'experiments'.
posted by lucidprose at 9:39 AM on September 18, 2010

Really? I accidentally did that once, trying to cool it down quickly and forgot about it- it blew up. My flatmates gave me hell about it :D

Yeah, the top and bottom of the can had ballooned out and were convex instead of concave. Maybe it was a different metal or different shape to yours?
posted by EndsOfInvention at 9:45 AM on September 18, 2010

I've had coke cans explode in my freezer before and that is one hell of a mess. nothing close to that is currently visible in my ice box. I defrosted it only a few weeks ago and had any liquid leaked from the coke bottle I am pretty sure I would be seeing ice buildup somewhere there, which I don't. I really don't think anything close to the amount of liquid that is missing from the bottle is visible anywhere in my freezer or the fridge below. it can't have just disappeared either, so I'm still confused.
posted by krautland at 11:01 AM on September 19, 2010