The enthalpy of hydrogenation of cyclohexene is -119.5 kJ mol -1. If resonance energy of benzene is -150.4 kJ mol -1, its enthalpy of hydrogenation would be

Question

The enthalpy of hydrogenation of cyclohexene is -119.5 kJ mol -1. If resonance energy of benzene is -150.4 kJ mol -1, its enthalpy of hydrogenation would be (A) - 358.5 kJ mol-1 (B) - 508.9 kJ mol-1 (C) - 208.1 kJ mol-1 (D) - 269.9 kJ mol-1

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="Solution" src="https://cdn.tardigrade.in/q/nta/c-j489zl8cco73.png" /> Enthalpy of hydrogenation of benzene =3 Δ( H ) text Hydrogenation -( R . E ) =3 ×(-119 ⋅ 5)-(-150 ⋅ 4)=-358 ⋅ 5+150 ⋅ 4 =-208 ⋅ 1 kJ mol -1

Q. The enthalpy of hydrogenation of cyclohexene is $- 119.5 k J m o l^{- 1}$ . If resonance energy of benzene is $- 150.4 k J m o l^{- 1}$ , its enthalpy of hydrogenation would be

$- 358.5 k J m o l^{- 1}$

$- 508.9 k J m o l^{- 1}$

$- 208.1 k J m o l^{- 1}$

$- 269.9 k J m o l^{- 1}$

Enthalpy of hydrogenation of benzene
$= 3Δ (H)_{Hydrogenation} - (R . E)$
$= 3 \times (- 119 \cdot 5) - (- 150 \cdot 4) = - 358 \cdot 5 + 150 \cdot 4$
$= - 208 \cdot 1 k J m o l^{- 1}$

Q. The enthalpy of hydrogenation of cyclohexene is −119.5kJmol−1. If resonance energy of benzene is −150.4kJmol−1, its enthalpy of hydrogenation would be

−358.5kJmol−1

−508.9kJmol−1

−208.1kJmol−1

−269.9kJmol−1