The standard ethelpy of combustion at `25^(@)C` of hydrogen, cyclohexene `(C_(6)H_(10))`, and cyclohexane `(C_(6)H_(12))` are `-241,-3800`, and `-3920 kJ mol^(-1)` repectively. Calculate the heat of hydrogenation of cyclohexane.

Options

A. `-121KJ` per mol
B. `+121KJ` per mol
C. `+242KJ` per mol
D. `-242KJ` per mol

Answer

C

Explanation

`DeltaH=[DeltaH` of cobustion of cyclohexane `-(DeltaH` of combustion of cyclohexene `+DeltaH` of combustion of `H_(2)]`
`=-[-3920-(-3800-241)]KJ`
`=-[-3820+4041]KJ=-121KJ`