Heat of Vaporization from Vapor Pressure (Example) 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 thermodynamics $\Delta \bar{h}_{vap}$ and $\Delta \bar{s}_{vap}$ from vapor pressure vs. temperature data Chemistry Stack Exchange Calculated and Experimental Enthalpies vap H and vap H exp of Download Table Solved Heat, q, is energy transferred between a system and Chegg.com