Measurements at 25 °C with a flow calorimeter and a flow densimeter have led to heat capacities and densities of aqueous solutions of H3PO4, NaH2PO4, Na2HPO4, Na3PO, NaHCO3, Na2CO3, H2SO4, and various buffer solutions. Results are presented in terms of apparent molar heat capacities [Formula: see text] and apparent molar volumes [Formula: see text]. Analysis of the experimental [Formula: see text] values to obtain the desired standard state [Formula: see text] values for single electrolytes requires that allowance be made for hydrolysis and dissociation reactions of certain solutes, along with extrapolation to zero concentration. Analysis of [Formula: see text] values requires similar considerations of hydrolysis and dissociation reactions, allowance for enthalpy and equilibrium changes ("relaxation") during calorimetric measurements, and extrapolation to zero concentration. Procedures for these calculations are presented. The [Formula: see text] and [Formula: see text] values that result from all of these measurements and calculations are used to obtain ΔCp0 and ΔV0 values for acid dissociation reactions, which are then related to effects of temperature and pressure on other thermodynamic properties.

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