Determinations of combustion and formation enthalpies of C60 and C70

By using a micro-bomb calorimeter, the standard enthalpies of combustion of C₆₀ and C₇₀ have been determined to be - (25 947.1±8.5) and - (29 956.1 ± 8.9) kJ/mol respectively. A g. 1. c. analysis indicated that the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible. The energy of combustion ofC60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in the molecules of C₆₀ and C₇₀ were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different methods are very close. Project supported by the National Natural Science Foundation of China (Grant No. 29473143)