The heats of combustion of methyl and ethyl alcohols

Abstract

The heats of combustion of gaseous methyl and ethyl alcohols, at saturation pressure, from their mixture with air, under a constant total pressure of 1 atmosphere , were found to be 763.68 ±0.20 for methyl alcohol at 25° C. and 1,407.50 ± 0.40 for ethyl alcohol at 32.50° C, in international kilojoules per mole. By combining with these data the heats of vaporization recently determined by Fiock, Ginnings, and Holton and correcting the data for ethyl alcohol to 25° C, the heats of combustion of the alcohols in the liquid state are computed to be 726.25 ±0.20 for methyl alcohol and 1,366.31 ±0.40 for ethyl alcohol, at 25° C. and a constant pressure of 1 atmosphere, in international kilojoules per mole. With the factor 1.0004/4.185 these values become, respectively, 173.61 ±0.05 and 326.61 ±0.10 kg-cali 5 per mole. It was found that a rapid and accurate determination of the ratio of carbon to hydrogen in a volatile organic liquid can be made by saturating a stream of inert gas with the vapor of the liquid and then passing the mixture through hot copper oxide.