The enthalpy of combustion at 25° 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 cyclohexene is :

Question

The enthalpy of combustion at 25° 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 cyclohexene is : (A) - 121 kJ/mol (B) + 121 kJ/mol (C) - 242 kJ/mol (D) + 242 kJ/mol

Tardigrade Admin · Accepted Answer

H 2+(1/2) O 2 longrightarrow H 2 O Δ H=-241 kJ ... (i) C 6 H 10+(17/2) O 2 longrightarrow 6 CO 2+5 H 2 O Δ H=-3800 kJ ...(ii) C 6 H 12+9 O 2 longrightarrow 6 CO 2+6 H 2 O Δ H=-3920 kJ ...(iii) hydrogenation of cyclohexene- C 6 H 10+ H 2 longrightarrow C 6 H 12 Eq (i) + Eq (ii) - Eq (iii) Δ H =-241-3800-(-3920) =-4041+3920 =-121 kJ

Q. The enthalpy of combustion at 25∘C of H2​, cyclohexane (C6​H12​) and cyclohexene (C6​H10​) are −241,−3920 and −3800kJ/mol respectively. The heat of hydrogenation of cyclohexene is :

- 121 kJ/mol

+ 121 kJ/mol

- 242 kJ/mol

+ 242 kJ/mol

Q. The enthalpy of combustion at $2 5^{\circ} C$ of $H_{2}$ , cyclohexane $(C_{6} H_{12})$ and cyclohexene $(C_{6} H_{10})$ are $- 241, - 3920$ and $- 3800 k J / m o l$ respectively. The heat of hydrogenation of cyclohexene is :