Chapter 7, Problem 136IP

In Exercise 89 in Chapter 3, the Lewis structures for benzene (C₆H₆) were drawn. Using one of the Lewis Structures, estimate $\Delta H_f^{°}$ for C₆H₆(g) using bond energies and given that the standard enthalpy of formation of C(g) is 717 kJ/mol. The experimental $\Delta H_f^{°}$ value for C₆H₆ (g) is 83 kJ/mol. Explain the discrepancy between the experimental value and the calculated $\Delta H_f^{°}$ value for C₆H₆(g).