Delta_(r)H^(Theta) of Cyclohexene (l) and benzene at 25^(@)C is -156 and + 46kJ mol^(-1), respectively. Delta_("hydrogenation")H^(Theta) of cyclohexene (l) at 25^(@)C is -119 kJ mol^(-1) Resonance energy of benzene is found to be -38x kJ mol^(-1). Find the value of x

Delta_(r)H^(Theta) of Cyclohexene (l) and benzene at 25^(@)C is -156 a

1.	Delta_(r)H^(Theta) of Cyclohexene (l) and benzene at 25^(@)C is -156 and + 46kJ mol^(-1), respectively. Delta_("hydrogenation")H^(Theta) of cyclohexene (l) at 25^(@)C is -119 kJ mol^(-1) Resonance energy of benzene is found to be -38x kJ mol^(-1). Find the value of x
Answer» Solution :`+H_(2(g))rarrDeltaH^(THETA)=-119 kJ mol^(-1)` This SHOWS that the generation of ONE (C=C) bond in cyclohexene requires 119 kJ `mol^(-1)` of enthalpy. To calculate RE resonance energy. `DeltaH_(1)^(Theta)=DeltaH_(2)^(Theta)=DeltaH_(3)^(Theta)=119 kJ mol^(-1), DeltaH_(4)^(Theta)=RE` `DeltaH_(5)^(Theta)=Delta_(f)H^(Theta)"(benzene)"-Delta_(f)H^(Theta)"(Cyclohexene)"` `=46-(-156)=205kJ mol^(-1)""therefore" From Hess' LAW"` `DeltaH_(4)^(Theta)=DeltaH_(5)^(Theta)-(DeltaH_(1)^(Theta)+DeltaH_(2)^(Theta)+DeltaH_(3)^(Theta))` `=205-3xx119=-152 kJ mol^(-1)""therefore-38x=-152` x=4.