A) b) ln((p2) (p1)) = ( Hvap) (R)((1) (T1) ( If \Delta {H}{vap }^{\circ} for {H}{2} {O} is 44 {kJ} {mol}^{ 1}, then amount of heat required to evaporate 9 {~g} of {H}_{2} {O} is : Enthalpy of vaporization Wikipedia The difference between `Delta`H and `Delta`U at constant volume is equal to 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 Vap H Latent Heat of Vaporization Delta Hvap of Water calculated by corresponding states correlation in a one cell excel formula