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?

On a cold night, if you pour out a bucket of water on a solid surface (say, a frozen pond, or a paved street), it is possible (maybe) that hot water could freeze faster than cold. As the water spreads thin over the pond, the exterior of the pool of water begins to freeze, solidifying the entire pool. The cold water WILL freeze faster than the hot on the exterior surface of the pool, causing a thicker pool with a liquid center. Once the thickness of the pool is set, the time required to freeze the center will be proportional to the thickness as well as the starting temperature of the water. One can imagine cases where the thickness is enough to overcome the difference in initial temperature, thus causing the hotter water to freeze completely before the colder water. I have no empirical data to support this claim, but it seems plausible.

Posted by Andy on 2003-11-19 17:01:41