13.7: The Gibbs Free Energy Chemistry LibreTexts The enthalpy of vaporization of \mathrm{H}{2} \mathrm{O}(1) is x \mathrm{~kJ} \mathrm{mol} and enthalpy of formation of water vapour \mathrm{ykJ} \mathrm{mol}. Enthalpy of formation of Enthalpy Changes delta h Nuclear Power 5.4: Vapor Pressure Chemistry LibreTexts Standard enthalpy of vaporization (vapH) for water at 100C is 40.66 kJ.. Delta H^0 vap of water is +40.79 kJ mol at 1 bar and 100 deg C. Change in internal energy for this__