How much heat must be removed from 0.90 kg of water at 0 ∘c to make ice cubes at 0 ∘c?

3.0x10^5 Joules Since the water is already at the freezing point, we just need to remove the enthalpy of fusion for water, which is 333.55 J/g. So: 0.90 kg * 1000 g/kg * 333.55 J/g = 300195 J Rounding to 2 significant figures means we have to remove 3.0x10^5 Joules of heat to freeze the water.