Abstract: A relation which can be used to calculate the difference between the heat capacity cp and cv for liquids at various temperatures has been established where R, T, V and α are gas constant, thermodynamic temperature, molar volume and thermal expansion coefficient respectively. A and B are two characteristic constants which can be obtained by the methods of group contribution and molecular topologic indexes. The calculated results agreed with experimental values satisfactorilly. The relation is also applicable to liquid mixtures, if simple mixing rule of A and B applies.

摘要： 建立了一个能够计算各种温度下液体恒压热容与恒容热容之差的关系式C_p-C_v=RTV~2a/(V~2-AV+B)A和B是两个相关的特性常数,它们的值可由基团贡献法和分子的拓外指数确定.计算结果与实验值相一致.倘若应用A和B的简单混合规则,上述关系式亦适用于液体混合物.