Water Properties: Vaporization Heat vs. Temperature Charts and Calculator Standard Enthalpy of Formation, \(\Delta H_{\rm f}^\circ \) Finding Delta H using ln P vs 1 T (Hvap Lab) 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 Delta Extrax Diamond Heights Disposable 3G D8 Gas