Volumetric behavior of glycine in aqueous succinic acid and sodium succinate buffer at different temperatures

Apparent molar volume (∅V) of glycine in aqueous succinic acid and in aqueous sodium succinate buffer solutions have been determined from precisely measured density data at different temperatures ranging from 288.15 to 328.15 K. The ∅V values of glycine in aqueous succinic acid solutions increase with increase in molality of glycine and temperature whereas ∅V values of glycine in sodium succinate buffer shows different behavior as a function of molality and temperature at pH = 1.00, 7.40 and 14.00. Partial molar volume at infinite dilution (∅Vo) and partial molar volume of transfer (∆ Vtr) has been determined from ∅V. Both positive and negative ∆ Vtr values have been observed for glycine in the presence of sodium succinate buffer solutions, whereas only negative, ∆ Vtr values have been observed in the presence of aqueous succinic acid solutions. Partial molar expansibilities∂∅Vo∂TPdetermined from ∅Vo data, are higher in the presence of buffer solutions as compared to that of aqueous succinic acid solutions. Hydration numbers (nH) for glycine in aqueous succinic acid solutions are higher than in aqueous sodium succinate buffer solutions at pH 7.40, which suggest a dehydration effect in later case.