The enthalpy of combustion for the H2, cyclohexene and cyclohexane are -241, -3800 and -3920 kJ mol-1 , respectively. Heat of hydrogenation of cyclohexene is

Question

The enthalpy of combustion for the H2, cyclohexene and cyclohexane are -241, -3800 and -3920 kJ mol-1 , respectively. Heat of hydrogenation of cyclohexene is (A) 121 kJ mol-1 (B) -121 kJ mol-1 (C) +242 kJ mol-1 (D)  - 242 kJ mol-1

Tardigrade Admin · Accepted Answer

H 2+(1/2) O 2 longrightarrow H 2 O , Δ H=-241 kJ dots(i) C 6 H 10+(17/2) O 2 longrightarrow 6 CO 2+5 H 2 O Δ H=-3800 kJ dots(ii) C 6 H 12+9 O 2 longrightarrow 6 CO 2+6 H 2 O Δ H=-3920 kJ dots(iii) For the reaction, C 6 H 10+ H 2 longrightarrow C 6 H 12 Adding Eqs. (i) and (ii) then subtracting Eq. (iii), we get Δ H=-241-3800-(-3920)=-121 kJ

Q. The enthalpy of combustion for the $H_{2}$ , cyclohexene and cyclohexane are $- 241, - 3800$ and $- 3920 k J m o l^{- 1}$ , respectively. Heat of hydrogenation of cyclohexene is

$121 k J m o l^{- 1}$

$- 121 k J m o l^{- 1}$

$+ 242 k J m o l^{- 1}$

$- 242 k J m o l^{- 1}$

Q. The enthalpy of combustion for the H2​, cyclohexene and cyclohexane are −241,−3800 and −3920kJmol−1 , respectively. Heat of hydrogenation of cyclohexene is

121kJmol−1

−121kJmol−1

+242kJmol−1

−242kJmol−1

Q. The enthalpy of combustion for the $H_{2}$ , cyclohexene and cyclohexane are $- 241, - 3800$ and $- 3920 k J m o l^{- 1}$ , respectively. Heat of hydrogenation of cyclohexene is

$121 k J m o l^{- 1}$

$- 121 k J m o l^{- 1}$

$+ 242 k J m o l^{- 1}$

$- 242 k J m o l^{- 1}$