So what's the physics behind this?

[Fat Tone]

http://www.break.com/index/corona_beer_freezing_trick2.html

Come to think of it, why is tapping a can supposed to stop it fizzing over too?

[Dr Mordrid]

Everyone knows that salt depresses the freezing point of water. So does CO2 in solution.

When you tap the just-opened cold beer much of the CO2 that has been held in solution by the high pressure of a capped bottle suddenly comes out of solution. The beer that is already below 32F/0C quickly freezes since with the CO2 out of solution it is now below the freezing point.

The theory goes that if the can is opened immediately after shaking it's very likely that the liquid inside will spray all over the place because some will be pushed ahead of escaping bubbles that had been adhering to the whole inside surface of said can. When the can is tapped before opening these bubbles can be jarred free. Assuming the can is upright the released bubbles, being lighter than the liquid, will float to the top of the can and escape without pushing the liquid ahead of them.

Personally I put a shaken can back in the fridge and grab another one. After a bit in there it re-stabilizes.

[Fat Tone]

That seems to make sense Doc, but the bottle in the video doesn't appear to be opened.

[Dr Mordrid]

Taking a break while I freeze a bottle of beer and try it.

[Nowhere]

I think Doc is on right track in the long post; however on this case it seems that the beer is on the brink of freezing; smashing it releases some CO2 which changes (hightens) freezing point of the beer.

Don't take it certainity at all, I'm currently drunk a bit (otoh - thanks to beer, so perhaps I'm especially qualified to discuss the matter atm ;P )

[Marshmallowman]

super cooling

http://en.wikipedia.org/wiki/Supercooled

Similar to super heating, heat water drop in some impurity(eg coffee) and it suddenly boils over.

If you do it just right on a hot day you can get just enough ice in a cold beer to keep ice cold while you drink it. Works even better with premix cans like burbon and coke, becasue you usually have ice with burbon and coke anyway.

We regularlly try to get can at "just that poiont" in summer...nothing beats a self icing drink.

[Brian Ellis]

I agree with MMM. I've seen liquid water at -20°C which will freeze instantaneously at any disturbance.

[Nowhere]

So, modyfying it a bit more - perhaps microbubbles of CO2 that show up when the whole thing is disturbed are the "impurity" that triggers solidification? (yup, still drunk, disclaimer applies...)

BTW, perfetc movie for this thread
http://www.imdb.com/title/tt0096486/ (WTF?! How can it only have 4.5 on imdb, it's EPIC! )

[Marshmallowman]

Just to add a word of caution, when the freeze occurs the liquid expands, this means glass bottles can and do explode. When we do it, opening the can bottle usually triggers the freeze but since its open no boom.

We have had quite a few incidents of expanded cans and exploded bottles(or pressure leaks out the lid) in the freezer.

This can be due to consuming to many super coolies and forgetting about the rest in the freezer

Your high alcohol mixers(>6% by volume) are usualy unlikely to pop, but lower alcohol beer(<4.5%) does tend blow with more regularlity. Standard beer (5%) needs a bit of caution, I have had a 5% large beer bottle(750ml) crack in my hands, so handle gingerly until until the bottle is opened.

So let the experimentation comence

[VJ]

That seems to make sense Doc, but the bottle in the video doesn't appear to be opened.

They did this on one of those science-like shows in NGC. The trick is to put the bottle down quite hard: it will have the effect Doc describes (bubbles moving upward). On top of this, the liquid is also supercooled (the bubbles moving upward create a distortion).


Jörg

[knirfie]

super cooling

http://en.wikipedia.org/wiki/Supercooled

Similar to super heating, heat water drop in some impurity(eg coffee) and it suddenly boils over.

If you do it just right on a hot day you can get just enough ice in a cold beer to keep ice cold while you drink it. Works even better with premix cans like burbon and coke, becasue you usually have ice with burbon and coke anyway.

We regularlly try to get can at "just that poiont" in summer...nothing beats a self icing drink.

Easiest way to achieve superheating is by puting a cup of distilled water in the microwave (one with a rotating plate) and stop the plate from rotating. This way the water is heated above boiling point because of the abscence of motion in the water.

once the water is disturbed (large movement or adding an impurity) the water suddenly starts boiling and may "explode" if temperature is high enough.

[Dr Mordrid]

Yup...my wife did that once when warming water for tea. The carousel drive failed and....

[Fat Tone]

Someone failed:

[Jon P. Inghram]

Another interesting freezing water trick is ice spikes when freezing distilled water (although I've had it happen with regular tap water too.)