[Rutherford]

At the hydrogenation of 1 mole of cyclohexene, 119kJ of heat was released, and at the total hydrogenation of 1 mole of benzene, 201kJ of heat was released. How much heat is released/absorbed at the catalytic disproportion of 49.2g of cyclohexene?

I thought that the disproportion is when cyclohexene is converted to benzene by releasing 2H₂, so I calculated this way:
ΔH₁=-119kJ/mol
ΔH₂=-201kJ/mol
ΔH=ΔH₁-ΔH₂=82kJ/mol
Q=ΔH*n=49.2kJ of heat absorbed. The answer is that 31.2kJ of heat was released.

[sjb]

At the hydrogenation of 1 mole of cyclohexene, 119kJ of heat was released, and at the total hydrogenation of 1 mole of benzene, 201kJ of heat was released. How much heat is released/absorbed at the catalytic disproportion of 49.2g of cyclohexene?

I thought that the disproportion is when cyclohexene is converted to benzene by releasing 2H₂, so I calculated this way:
ΔH₁=-119kJ/mol
ΔH₂=-201kJ/mol
ΔH=ΔH₁-ΔH₂=82kJ/mol
Q=ΔH*n=49.2kJ of heat absorbed. The answer is that 31.2kJ of heat was released.

In effect your reaction is 3 cyclohexene  2 cyclohexane + 1 benzene

[Rutherford]

Strange reaction(mine guess was,too), but it seems correct as I got the right answer. Is there a mechanism here on the net for the reaction you gave?

[sjb]

Strange reaction(mine guess was,too), but it seems correct as I got the right answer. Is there a mechanism here on the net for the reaction you gave?

Of course the whole point here is that you don't need a mechanism, but perhaps look into oxidative addition across C-H bonds with transition metals etc.

[Rutherford]

Still, that didn't help me to understand how that reaction happens.

[camptzak]

so your giving the enthalpy change for the hydrogenation of cyclohexene and benzene. and you give a stoichiometry problem at the end there. but wat you really want to know is the mechanism? correct?

[Rutherford]

I was just curious after sjb told me that reaction.