The enthalpy of hydrogenation of cyclohexene is -120 kJ mol-1 and that of benzene is -208 kJ mol-1. What is the delocalisation energy of benzene?
Answer and explanation
Correct answer: C. 152 kJ mol-1
- Step 1: A hypothetical Kekule benzene with three C=C bonds would release kJ mol-1. Step 2. Actual release is 208, so benzene is more stable by kJ mol-1. Answer: 152 kJ mol-1. Why not the others: 88 is ; 328 is ; 360 is the predicted value for the Kekule structure itself.
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