A SYSTEM OF MOLECULAR THERMOCHEMISTRY FOR ORGANIC GASES AND LIQUIDS

An analysis has been made of the heats of formation and combustion of organic gases and liquids, and of the heats of vaporization of liquids. The work has been done as far as possible with homologous series, in order to discover systematic effects. The data are converted into heats of atomization, i.e., the heats required to convert the gases or liquids into their constituent atoms. It is shown that the heats of atomization of the gaseous aliphatic hydrocarbons (paraffins, olefins, and acetylenes) can be accurately represented by a scheme in which a distinction is made between primary, secondary, and tertiary carbon–hydrogen bonds, and between bonds that are next to, and next but one to, multiple bonds. For aromatic molecules an appropriate correction for resonance is proposed. For other types of compound it is found that suitable values for the various bonds (e.g., C–CHO, C–OH) will give rise to good agreement with experiment.It is shown that to a reliable approximation heats of vaporization are also ame...

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