Cyclohexene H 2- Ni Cyclohexane - - H -28-6 kcal - molAnthracene H 2- Ni Tetradecahydroanthracene - - H -116-2 kcal - molThe resonance energy of anthracene is x kcal - mol- Magnitude of x is-

Enthalpy of hydrogenation of cyclohexene = 28.6 kcal/mol ∴ Calculated enthalpy of anthracene = 28.6× 7= 200.2 kcal/mol (As there are 7 double bonds in anthracen ...

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Standard XII

Chemistry

Introduction to Alkenes

Cyclohexene H...

Question

$Cyclohexene H_{2} - \to N i Cyclohexane; Δ H = - 28.6 kcal/mol$

$Anthracene H_{2} - \to N i Tetradecahydroanthracene; Δ H = - 116.2 kcal/mol$

The resonance energy of anthracene is $x kcal/mol$ . Magnitude of $x$ is:

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Solution

Enthalpy of hydrogenation of cyclohexene $= - 28.6 kcal/mol$
$∴$ Calculated enthalpy of anthracene $= - 28.6 \times 7 = - 200.2 kcal/mol$
(As there are 7 double bonds in anthracene)
Hence, $Resonance energy = Calculated enthalpy- Actual enthalpy$
$= - 200.2 - (- 116.2) kcal/mol$
$= - 84 kcal/mol$
Therefore, magnitude of $x$ is 84.

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CyclohexeneH2−→NiCyclohexane ; ΔH=−28.6 kcal/mol AnthraceneH2−→NiTetradecahydroanthracene ; ΔH=−116.2 kcal/mol The resonance energy of anthracene is x kcal/mol. Magnitude of x is:

$Cyclohexene H_{2} - \to N i Cyclohexane; Δ H = - 28.6 kcal/mol$

$Anthracene H_{2} - \to N i Tetradecahydroanthracene; Δ H = - 116.2 kcal/mol$

The resonance energy of anthracene is $x kcal/mol$ . Magnitude of $x$ is: