The enthalpy of hydrogenation of cyclohexane is `-119.5 kj*mol ^(-1)`. If resonance energy of benzene is `-150.4 kJ*mol^(-1)`, estimate its enthalpy of hydrogenation.

Explanation

Enthaply of hydrogenation of cyclohexane `=-119.5 kJ.mol^(-1)`
So enthapy of hydrogenation of hypothetical cyclohexatriene `=3xx-119.5kJ .mol^(-1)`.
In otherwards , the calculated (or theoretical ) enthalpy of hydrogenation of benzene `=-3xx119.5 kJ.mol^(-1)`
Let the actual (i.e, experimental ) enthalpy of hydrogenation of benzene `=x kJ .mol^(-1)`
Now R.E of benzene =calculated enthalpy of hydrogenation of benzene - actual enthalpy of hydrogenation of benzene
so, `-150.4=-3xx119.5-x`
or, `x=-3xx119.5+150.4=-208.1 kJ.mol^(-1)`