Phase Transitions General Chemistry For water vap H = 41 kJ mol^1 at 373 K and 1 bar pressure. Assuming that water vapour Sarthaks eConnect Largest Online Education Community Enthalpy and Phase Transitions CK 12 Foundation 5) For vaporization of water at 1 bar, \Delta H = 40.63 \mathrm {kJ} \ma.. Heat of Vaporization of Water Heats of Vaporization and Condensation Examples, Calculations and Definitions CK 12 Foundation