Calorimetric determination of the heats of combustion of ethylene and propylene

The data of the present investigation give for the heats evolved in the combustion of gaseous ethylene and propylene in oxygen, at 25° C and a constant pressure of 1 atmosphere, to form gaseous carbon dioxide and liquid water, the following values in international kilojoules p er mole: ethylene, 1410.97 ± 0.30; propylene, 2057.42 ± 0.62.Converted to kilocalories by means of the factor 1/4.1833, these values become, respectively, 337.28 ± 0.07 and 491.82 ± 0.15 kilocalories p er mole.A review of the existing data indicates that the hitherto " best" values for the heats of combustion of these ga~es differ fron the values obtained in the prese nt investigation by -1.6 percent for ethylene and -0.4 percent for propylene.These differences are, res pectively, about 75 and 12 times the estimated uncertainties in the new values.