Standard molar enthalpies of formation of cyclohexane(l) and benzene (l)  at  25°C are -156 and +49KJ  mol-1 respectively. The standard enthalpy of hydrogenation of cyclohexene (l) at 25°C is −119KJ/mol using data calculate the resonance energy of benzene.

By using above data,theoretical heat of formation of benzene is calculated6C+6H2→C6H12(t);ΔH1=-156KJmol-1C6H10+H2→C6H12;ΔH2=-119KJmol∴heat of hydrogenation of benzene 3 times that of heat of hydrogenation of cyclohexene, benzene involves reduction of 3 double bonds.∴C6H6+3H2→C6H12(1);ΔH3=3(-119)=-357KJmol-16Cs+3H2→C6H6;ΔH=?ΔH=ΔH1-ΔH3=+201KJmol-1∴ resonance energy =ΔjHexp-ΔfHca=49-201=-152KJmol-1