Many have heard the "old wives tale" stating that if you put hot water into a freezer, it freezes in less time than it would have if it had been cold to start. Never did I believe such a claim, as it runs contrary to one of the basic laws of nature.

While surfing one day on sites illustrating "bad science" I actually found a plausible real life reason why this in fact can be true (read:not always true, but possible). Running this experiment under controlled conditions [eg. measure the same volumes of hot and cold water, make sure containers are equal in any relevant aspect (shape, material, conductance properties, covered or not etc.), and that the freezer is properly set to achieve a uniform temperature throughout], can you come up with a reasonable set of conditions for which the water in the hot container would freeze before the water in the cold container?

water particles in hot water have greater kinetic energy than those in cold water. high energy compounds are more unstable and so lose energy more quickly, i.e. warm water will cool down more quickly (relatively speaking) than cold water. however, once the hot water has cooled down to such an extent that it is just as cold as the cold water was originally, it will then take the same amount of time to freeze from this temperature - and therefore, hot water - under any conditions - should take longer to freeze than cold water, according to the laws of thermodynamics and kinetic theory.

Posted by sean on 2003-12-17 15:44:26