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?

I always thought this problem had to do with the fact that the density of water changes at different temperature. At 4 degrees centigrade, water has a specific gravity of 1. It turns out that this falls off as the temperature decreases. So while you may have the same volume of cold water and hot water, they actually are different in mass. And from all those heat equations from chemistry, it is mass, not volume, that indicates how much energy is needed to heat/cool water.

Posted by Stewie on 2003-05-13 23:26:41