Is the amount of heat released when 1 gram of liquid freezes (at its freezing point). Is the amount of heat needed to melt 1 gram of a solid (at its melting point). The heat needed to freeze (or melt) a specific mass of water (or ice) is calculated using the heat of fusion. Example: How much heat in cal is needed to melt 15.0 g of water? A. How many calories are needed to melt 5.00 g of ice at 0C? B. How many calories are released when 25.0 g of water at 0C freezes? A. How many calories are needed to melt 5.00 g of ice at 0C? B. How many calories are released when 25.0 g of water at 0C freezes?