Does hot water freeze faster than cold water? Reproducing the Mpemba effect. (2010)
Undergraduate: Andrew Collins
Faculty Advisor: Stephen Shafroth
Department: Physics & Astronomy
In this experiment, different samples of water are being studied as they freeze in order to observe the Mpemba effect, the phenomenon that water starting at a higher initial temperature will freeze before the same volume of water starting at an initially lower temperature. The two thousand-year-old Mpemba effect, discovered by Erasto B. Mpemba and notably observed by Descartes and Aristotle, is stirring debates in the current scientific community. Impurities in the water are known to change the freezing point of water, but it has been shown they also influence the minimum supercooled temperature of liquid water. J. D. Brownridge has shown that two “equivalent” samples of water will become supercooled and then freeze at different times. If these times are greater than 5 minutes, then the sample which freezes first is heated in a sealed container, and it freezes faster than the other sample nearly all the time. We are testing this claim with bottled and tap water.