Water Properties: Vaporization Heat vs. Temperature Charts and Calculator Enthalpy of vaporization Wikipedia 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 vp vs temp.svg 10.10: Enthalpy of Fusion and Enthalpy of Vaporization Chemistry LibreTexts