Entropy of Vaporization an overview ScienceDirect Topics q = n delta H, Units, Formula, Equation, Examples, How to use? 5) For vaporization of water at 1 bar, \Delta H = 40.63 \mathrm {kJ} \ma.. Calculating Energy Change Phase Change Easy Peasy All in One High School Standard enthalpy of vaporisation`DeltaV_(vap).H^(Theta)` for water at `100^(@)C`is`40.66kJmol^( 1)`.Teh internal energy of Vaporization of water at` 100^(@)C("in kJ mol"^( 1))`is Heat of Vaporization of Water