The standard enthalpy of combustion at 25∘ C of hydrogen, cyclohexene (C6H10) and cyclohexane (C6H12) are -241, -3800 and -3920 KJ/mole respectively. Calculate the heat of hydrogenation of cyclohexene.

Q. The standard enthalpy of combustion at

25^{o} C

of hydrogen, cyclohexene (

C_{6} H_{10}

) and cyclohexane (

C_{6} H_{12}

) are

- 241, - 3800 a n d - 3920 k J m o l^{- 1}

respectively. Calculate the heat of hydrogenation of cyclohexene ( in

k J m o l^{- 1}

)

Q. The standard enthalpy of combustion at

25^{o} C

of hydrogen, cyclohexene (

C_{6} H_{10}

) and cyclohexane (

C_{6} H_{12}

) are

- 241, - 3800 a n d - 3920 k J m o l^{- 1}

respectively. Calculate the heat of hydrogenation of cyclohexene ( in

k J m o l^{- 1}

)

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The enthpaly combution at 25 ∘C of H2, cyclohexane (C6H12) and cyclohexene (C6H10) are −241, −3920 and −3800 kJ/mol respectively. The heat of hydrogenation of cyclohexenes:

The correct option is A −121 kJ mol−1H2(g)+12O2(g)→H2O(l) (ΔH=−241 kJ)..(i) C6H10+172O2(g)→6CO2(g)+5H2O(l) (ΔH=−3800 kJ)..(ii) C6H10+9O2(g)→6CO2(g)+6H2O(l) (ΔH=−3920 kJ)..(iii) Eq. (i) + eq. (ii) − eq. (iii) gives ΔH=−241−3800−(−3920)=−121 kJ

The enthpaly combution at $25^{\circ} C of H_{2}$ , cyclohexane $(C_{6} H_{12})$ and cyclohexene $(C_{6} H_{10})$ are $- 241, - 3920$ and $- 3800 kJ/mol$ respectively. The heat of hydrogenation of cyclohexenes: