At `25^(@)C`, standard enthalpy of combustion of combustion of hydrogen, cyclohexene `(C_(6)H_(10))` and cyclohexane `(C_(6)H_(12))` are `-241, -3800 and -3920 " kj mol"^(-1)` respectively. Determine the heat of hydrogenation of cyclohexene.

Explanation

`H_(2)+(1)/(2)O_(2)to H_(2)O , Delta H^(0)= - 241 " kJ mol"^(-1)` ..[1]
`C_(6)H_(10)+(17)/(2)O_(2)to 6CO_(2)+5H_(2)O , Delta H^(0) = -3800 " kJ mol"^(-1)` ..[2]
`C_(6)H_(12)+9O_(2) to 6 CO_(2)+6H_(2)O, Delta H^(0) = -3920 " kJ mol"^(-1)` ..[3]
`1 xx eq.[2]+1xx eq.[1] - eq.[3] ` we have,
`C_(6)H_(10)+H_(2) to C_(6)H_(12), Delta H^(0)=(-3800-241+3920) kJ= -121 kJ`