Enthalpy Changes delta h Nuclear Power Delta H^0 vap of water is +40.79 kJ mol at 1 bar and 100 deg C. Change in internal energy for this__ If \Delta {H}{vap }^{\circ} for {H}{2} {O} is 44 {kJ} {mol}^{ 1}, then amount of heat required to evaporate 9 {~g} of {H}_{2} {O} is : 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 5.4: Vapor Pressure Chemistry LibreTexts