Question

When you freeze water, 80 calories of heat are released into the surroundings for every gram of water that freezes. This is known as the "latent heat of fusion" of water, which is 80 cal/g. Heat of fusion is a characteristic property. Theoretically, if you could "capture" all the heat that is released into a tightly sealed container, by freezing 10 gallons of water: How much heat would you be obtaining?

Answer 1

One gallon of water weighs 8.35 lb and has a mass of
8.35 lbm*454 g/lbm = 3791 g

Multiply that by the heat of fusion (per gram)

Your answer will be in calories.