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

(i) H 2+1 / 2 O 2 longrightarrow H 2 O , Δ H=-241 kJ (ii) C 6 H 12+9 O 2 longrightarrow 6 CO 2+6 H 2 O , Δ H=-3920 kJ (iii) C 6 H 10+(17/2) O 2 longrightarrow 6 CO 2+5 H 2 O , Δ H=-3800 kJ Required reaction is C 6 H 10+ H 2 longrightarrow C 6 H 12, Δ H=? Eq. (i) + eq. (iii) - eq. (ii) Δ H=-241-3800-(-3920)=-4041+3920=-121 kJ

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

$- 121 k J / m o l$

$+ 121 k J / m o l$

$- 242 k J / m o l$

$+ 242 k J / m o l$

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

−121kJ/mol

+121kJ/mol

−242kJ/mol

+242kJ/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

$- 121 k J / m o l$

$+ 121 k J / m o l$

$- 242 k J / m o l$

$+ 242 k J / m o l$