When Hot Water Freezes Before Cold---The Mpemba Effect

Jonathan Katz, Subatomic Physics - LANL

Abstract: I suggest that the origin of the Mpemba effect (the freezing of hot water before cold) is freezing-point depression by solutes, gaseous or solid, whose solubility decreases with increasing temperature so that they are removed when water is heated. They are concentrated ahead of the freezing front by zone refining in water that has not been heated, reduce the
temperature of the freezing front, and thereby reduce the temperature gradient and heat flux, slowing the progress of the front. I present a simple calculation of this effect, and suggest experiments to test this hypothesis.

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