Math and Arithmetic

How many BTUs will it take to change 1 gallon of water at 32 degrees to ice at 32 degrees?



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You would need to remove approximately 1200 BTUs of heat to convert a gallon of water to ice. There are 8.34 lb in a gallon of water, which converting to lb-moles is 0.463. The latent heat of crystallization for water is -2583.4 BTU/lb-mole. Multiplying the two together and you get -1197 BTUs, which means you need to remove that amount of heat to convert the gallon of water to ice.