From the following data, calculate the resonance energy of benzene (in kJ/mol, as a positive stabilisation).
Cyclohexene + $H_{2}$ $\to$ cyclohexane : ΔH = -120 kJ/mol
Benzene + $3 H_{2}$ $\to$ cyclohexane : ΔH = -208 kJ/mol

Question

From the following data, calculate the resonance energy of benzene (in kJ/mol, as a positive stabilisation).

Cyclohexene + $H_{2}$ $\to$ cyclohexane : ΔH = -120 kJ/mol

Benzene + $3 H_{2}$ $\to$ cyclohexane : ΔH = -208 kJ/mol

TestHub · Accepted Answer

Three isolated C = C bonds would liberate 3 × (-120) = -360 kJ/mol. The actual value is -208 kJ/mol, so benzene is more stable by 360 - 208 = 152 kJ/mol. The resonance energy is 152 kJ/mol.

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