Heat capacities and concentration fluctuations in mixtures of 1,2-dibromoethane with alkanes

Abstract

Excess volumes, excess heat capacities and light scattering have been measured for several 1,2-dibromoethane–alkane (n-heptane, n-octane, n-tetradecane, cyclooctane and 2,2,4-trimethylpentane) systems. The results show that there is good agreement between values of the concentration–concentration correlation function S_cc, as calculated from light-scattering data, and the predictions of the simple rigid lattice model of Flory and Huggins, which estimates the relative effects of the differences in molecular sizes and of differences in the interaction energies of the two components. The results also confirm the utility of S_cc as predictor of the existence of W-shaped excess isobaric heat capacity (C^E_P) curves, although other effects, such as the destruction of the (partial) correlation of molecular orientation may complicate this issue.