G. Keenan wrote:
G. Keenan wrote:
What's going on there? Is the beer basically at freezing point and opening it and tapping it on the counter causes it to fizz and freeze or something?
The liquid has been cooled below freezing temperature for a long period of time. However, in order for the "freezing" to occur, there has to be a starting point of some sort of particle that the frozen particles can form off of. In a supercooled liquid, there isn't any such particle (because it's a pure liquid--no solid present), and when he bangs the glass on the table, some solid particle makes its way into the bottle somehow so that the first few particles can freeze onto that particle, and it starts a chain reaction of sorts and the liquid freezes really quickly.http://en.wikipedia.org/wiki/Supercooling
So is that not real beer in the bottle then? Because if you put normal beer in the freezer it freezes.
I'm not sure. I had this happen with a plastic frosty mug once, the kind you keep in the freezer and filled with liquid around the sides. But it just happened the one time.
Put a few unopened bottles of beer in your freezer for a couple of hours (side note: the visual effect will work best with clear beer bottles, like Corona). When it comes time to remove the beers, you may notice a couple of them have frozen and "exploded," but there should also be a few that are still in a liquid state. Carefully pick these up, set them on the table, and remove the bottle caps.
At this point, the trick does itself… just give the bottle a good tap on the side of the counter, and as the bubbles start to form, the entire beer will instantly freeze, eventually pushing the ever-expanding ice out the mouth of the bottle.
Why does this work? In a word: supercooling. From Wikipedia:
Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid.
A liquid below its standard freezing point will crystallize in the presence of a seed crystal or nucleus around which a crystal structure can form. However, lacking any such nucleus, the liquid phase can be maintained all the way down to the temperature at which crystal homogeneous nucleation occurs. The homogeneous nucleation can occur above the glass transition where the system is amorphous (non-crystalline) solid.
In the case of our beers, when we strike the bottle, the gas bubbles that form immediately give the supercooled liquid a nucleus around which to freeze. It is possible to supercool water bottles in the same manner, but I've found it much easier with glass bottles of beer than plastic bottles of Diet Coke.
Remember that these are glass bottles filled with a supercooled liquid, and that water expands as it freezes to ice. I've never seen one of these violently explode, but I suppose it's possible. Make sure you take appropriate safety precautions.
…I'd mention something about kids not trying this, but then I just think "What kind of idiot gives a bunch of bottles of beer to kids for them to play with?"