The heat of vaporization or the enthalpy of vaporization is the amount of energy that must be added to a liquid substance, to transform a quantity of that substance into a gas. In this case; 2.7 moles of a substance released 472 kJ,
Therefore; 1 mole will release; 472/2.7 = 174.814
Hence; the heat of vaporization is 174.814 kJ/mol