The enthalpy of combustion of H2, cyclohexene (C6H10) and cyclohexane (C6H12) are -241,~-3800 and -3920 text kJ per mol respectively. Heat of hydrogenation of cyclohexene is

Question

The enthalpy of combustion of H2, cyclohexene (C6H10) and cyclohexane (C6H12) are -241,~-3800 and -3920 text kJ per mol respectively. Heat of hydrogenation of cyclohexene is (A)  -121 text kJ per mol (B)  +121 text kJ per mol (C)  +242 text kJ per mol (D)  -242 text kJ per mol

Tardigrade Admin · Accepted Answer

Δ H=[Δ H of combustion of cyclohexane -(Δ H of combustion of cyclohexene +Δ H of combustion of H2 )] =-[-3920-(3800-24)] text kJ =-[3920+4041] =-[121]kJ =-121kJ

Q. The enthalpy of combustion of $H_{2},$ cyclohexene $(C_{6} H_{10})$ and cyclohexane $(C_{6} H_{12})$ are $- 241, - 3800$ and $- 3920 k J$ per mol respectively. Heat of hydrogenation of cyclohexene is

$- 121 k J$ per mol

$+ 121 k J$ per mol

$+ 242 k J$ per mol

$- 242 k J$ per mol

$Δ H = [Δ H$ of combustion of cyclohexane $- (Δ H$ of combustion of cyclohexene $+ Δ H$ of combustion of $H_{2}$ )]
$= - [- 3920 - (3800 - 24)] k J$
$= - [3920 + 4041]$
$= - [121] k J$
$= - 121 k J$

Q. The enthalpy of combustion of H2​, cyclohexene (C6​H10​) and cyclohexane (C6​H12​) are −241, −3800 and −3920kJ per mol respectively. Heat of hydrogenation of cyclohexene is

−121kJ per mol

+121kJ per mol

+242kJ per mol

−242kJ per mol