| Abstract: | Accurate measurements of the enthalpies of combustion have been made on the following high-purity, liquid samples; 4-methyloctane, 3,3,5-trimethylheptane, 2,2,3,3-tetramethylhexane, 2,2,5,5-tetra-methylhexane, 2-methyldecane, 2,2,4,6,6-pentamethylheptane, 2,2,4,4,6-pentamethylheptane, and 2-methylpentadecane. In addition to the liquid samples, combustion data were obtained for high purity resorcinol and poly(vinyl methyl ether) and poly(vinyl ethyl ether). From these combustion data and appropriate auxiliary data, values have been calculated for the standard enthalpies of formation for these eight liquids and three solid compounds. Using the standard calorimetric enthalpies of vaporization for the C₄ to C₈ hydrocarbons as a framework, a modified, isomeric variation correlation was derived. The resulting values gave the standard enthalpies of formation of hydrocarbons in gaseous phase. These experimental data were compared with the values obtained from the Greenshields-Rossini and the Somayajulu-Zwolinski procedures. |
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