Effect of temperature on ionic volumes and heat capacities in methanol

A flow densimeter and flow heat capacity calorimeter have been employed to measure precision densities and specific heats of selected electrolytes and nonelectrolytes in methanol at 20, 25, and 40°C. Apparent molar volumes and heat capacities have been calculated and the corresponding standard state functions, V^o and C_p,^o, evaluated. The data have been used, along with known volumes and heat capacity data at 25°C for numerous alkanes, to generate volumes and heat capacities of model compounds for organic electrolytes. Comparison of the thermodynamic functions for the model compounds with those of the corresponding electrolytes at the respective temperatures has made it possible to assign single ion values and to establish the temperature effects of ionic charges on the volumes and heat capacities of solutes.