Precise density and sound velocity measurements have been carried out on tripotassium citrate in aqueous solutions of polypropylene oxide (PPO) 400 over a range of temperatures at atmospheric pressure. The data obtained are used to calculate the apparent molar volume and isentropic compressibility as a function of temperature and concentration. Apparent molar volume and isentropic compressibility values have been fitted to a Redlich−Mayer-type equation from which the apparent molar volume and apparent molar isentropic compressibility of the solutions at infinite dilution have also been calculated at each temperature. The results show a positive transfer volume of tripotassium citrate from pure water to an aqueous PPO solution. The apparent molar isentropic compressibility of tripotassium citrate in aqueous PPO solutions is negative which implies that the water molecules around the tripotassium citrate are less compressible than the water molecules in the bulk solutions.

Precise density and sound velocity measurements have been carried out on trisodium citrate in aqueous solutions of 0.000, 0.002, and 0.004m polyvinylpyrrolidone (PVP) at T ) (283.15 to 308.15) K at atmospheric pressure. From these experimental data, the apparent molar volume and isentropic compressibility values have been evaluated and fitted to a Redlich-Mayer-type equation from which the apparent molar volume and apparent molar isentropic compressibility of the solutions at infinite dilution have also been calculated at each temperature. The results show a positive transfer volume of trisodium citrate from an aqueous PVP solution to a more concentrated PVP solution. This indicates that the size of trisodium citrate is larger in a solution with higher PVP concentration. The apparent molar isentropic compressibility of trisodium citrate in aqueous PVP solutions is negative, which implies that the water molecules around the trisodium citrate are less compressible than the water molecules in the bulk solutions.

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