The temperature dependence of the vapor pressure is given by Solved Heat, q, is energy transferred between a system and Chegg.com Video answer for \Delta_{\text {vap }} \mathrm{H}^{\Theta} for water is +40.79 \mathrm{kJ} \mathrm{mol}^{ 1} at 1 bar and 100^{\circ} \mathrm{C}. Change in internal energy for this vapourisation under If Delta H_(vaporisation) of substance X (l) (molar mass : 30 g mol) is 300 J g at it\'s boling Heat of Vaporization: Acetone Lab Experiment