Question: how is heat of vaporization calculated?
Answer: Every substance has its own molar heat of vaporization. The units for the molar heat of vaporization are kilojoules per mole (kJ/mol). ... The molar heat of vaporization for water is 40.7 kJ/mol. To get the heat of vaporization, you simply divide the molar heat by 18.015 g/mol.