Law of Equipartition of Energy Energy is equally distributed among all degrees of freedom Each degree contributes kT per molecule Translational, rotational, Latent Heat of Vaporization Delta Hvap of Water calculated by corresponding states correlation in a one cell excel formula Chem Eng Musings vp vs temp.svg Standard enthalpy of vapourisation `Delta_("vap")H^( )` for water at `100^@C` is `40.66 kJ mol^( 1)`. The internal energy of vapourisation of water at `100^@C` (in kJ `mol^( 1)`) is (Assume water vapour to behave like DeltaH` (vap) for water is `40.7 kJ mol^( 1)`. The entropy of vapourisation of water is