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 : Standard enthalpy of vaporization (vapH) for water at 100C is 40.66 kJ.. Confusion about enthalpy and when to use h = m(Cp)(delta T) Do I have to use one or the other in this case? : r thermodynamics Enthalpy Changes delta h Nuclear Power 5.4: Vapor Pressure Chemistry LibreTexts Solved] 1. The boiling point of propane at 1 atm (14.7 psi) pressure is 42.0 C and its H(vap) is 18.8 kJ mol. R = 8.314 Course Hero