On the dependence of liquid heat capacity on temperature and molecular structure

Abstract

On the basis of the similarity of the shapes of the liquid heat capacity and vapour pressure curves, and the concept that a property such as heat capacity (energy storage capacity) should directly depend on the constitution and structure of the molecules, a corresponding state-type relation has been formulated and tested: C_σL = R_M(5.4571 − $\text{0.3098}\text{T}{}_{\mathrm{R}}\text{− 1}$) where C_σL (J mol⁻¹ K⁻¹) is the saturated liquid heat capacity, R_M (cm³ mol⁻¹) is the molar refraction and T_R is the reduced temperature. The extension of the method, which predicts liquid heat capacities of pure non-polar liquids with an average absolute deviation of 5.5%, to polar liquids and several binary mixtures is also discussed.