Question

Heat of dissociation of benzene to elements is 5535 kJ mol^–1 . The bond enthalpies of C–C, C=C, and C–H are 347.3, 615.0 and 416.2 kJ respectively. Resonance energy of benzene is

(a) 1.51 kJ

(b) 15.1 kJ

(c) 151 kJ

(d) 1511 kJ

Answer 1

Correct option  (c) 151 kJ

Explanation:

Experimental heat of atomization of benzene = 5535 kJ/mole.

Theoretical heat of atomization (breaking of 3 C–C bonds, 3C = C bonds and 6C – 4 bonds)

= 3× 347.3 + 3 x 615.0 + 6 x 416.2 = 5384.1;

Hence resonance energy = 5535 – 5384.1= 151kJ