… and I mean that literally. Here he is, supercooling a beer.
Supercooling is when a liquid is chilled to a temperature below its freezing point, but it remains a liquid. Water, for example, will crystallize when it freezes, but it needs a starting point for that to happen, like a particle of some impurity (a mineral, for example), or the rough wall of its container. If you freeze a container of (distilled) water without jostling it, it’s possible to supercool it. If you then carefully remove it from the freezer and shake it or pour it over ice, it’ll freeze instantly*.
This is similar to superheating, where a liquid can be heated beyond its boiling point but remain a liquid. This happens all the time for me when I boil water in my microwave using one particular Pyrex measuring cup. I have to be careful — I might say super careful — when removing it, because if jostled the water will erupt with steam and explode outwards. To call that dangerous is a massive understatement; water can carry a lot of heat and the resulting burns are no fun at all.
… which is how I discovered that particular measuring cup superheats the water. Ow.
Anyway, Brian Brushwood makes the great video series Scam School, and this video is for a book version he’s doing. I can’t wait to see that!
* I don’t suggest trying this without knowing what you’re doing; if the water does freeze inside the container it can rupture: ice has a larger volume than water.
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- My Picks – 15 January 2012 « Joy of Science | January 14, 2012