Chemistry in the Kitchen


Does hot water really freeze faster than cold water?

Sometimes. This observation is known as the “Mpemba effect,” named after the Tanzanian student who in 1963 resurrected the idea from Aristotle, Francis Bacon, and René Descartes. Whether or not this effect can be seen seems to depend on so many variables (the size and shape of the container, the initial temperatures of the two liquids, the method of cooling), on how you define freezing (when the first ice crystal forms, when there’s a solid layer on the top, or when all of the water has frozen solid), that it’s really still unclear if this effect is real or not.


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