ENTHALPIES OF COMBUSTION OF TOLUENE BENZENE CYCLOHEXANE CYCLOHEXENE METHYLCYCLOPENTANE 1-METHYLCYCLOPENTENE AND N-HEXANE

The enthalpies of combustion of toluene, benzene, cyclohexane, cyclohexene, methylcyclopentane, 1-methylcyclopentene, and n-hexane were measured in a bomb calorimeter. Values, in kilocalories per mole based on the mass of sample, for the enthalpies of combustion, ΔHc°298.15, of theliquid hydrocarbons in gaseous oxygen to form gaseous carbon dioxide and liquid water are toluene, -934.49 ± 0.12; benzene, -780.95 ± 0.10; cyclohexane, -936.87 ± 0.13; cyclohexene, -896.75 ± 0.12; methylcydopentane, -941.28 ± 0.14; 1-methylcyclopentene, -897.17 ± 0.13; and n-hexane, -995.03 ± 0.13. Values of the enthalpy of formation of the liquids were derived. They were compared to existing hydrocarbon data and can be used to check the internalconsistency of the existing selections ofdata for the several families of hydrocarbons. The best means of measuring the amount of reaction in combustion calorimetrywere reconsidered. Both sample mass and carbon dioxide recovery were used as measures of the amount of reaction. A new carbon dioxide absorbent was used and was superior to older absorbents. © 1969, American Chemical Society. All rights reserved.