Use the data in Thermodynamic Properties and the bond energy in Bond Energies to determine the average C-C bond energy in benzene (C₆H₆). kJ/mol Calculate the average of a C-C single bond and a C=C double bond using the bond energies, which is the value expected from the Lewis structure. kJ/mol The larger calculated value using thermodynamic properties is due to the fact that the pi system is delocalized, which makes the molecule more stable than predicted by simply averaging the C-C bonds.