The limiting partial molar volume and transfer partial molar volume of glycylglycine in aqueous sodium halide solutions at 298.15 K and 308.15 K

Apparent volumes VΦ of glycylglycine in aqueous NaX (X = F−, Cl−, and Br−) solutions have been obtained from densities of their solutions at 298.15 K and 308.15 K measured by using a precise vibrating-tube digital densimeter. These values have been utilized in conjunction with the values in water to deduce partial molar volumes of transfer ΔtrsVΦ∘ from water to different aqueous NaX solutions. ΔtrsVΦ∘ values are positive. The interpretation is that these results arise from the dominant interaction of the NaX with the charged centers of glycylglycine. The results show that ΔtrsVΦ∘ depend less on the temperature. Hydration numbers and interaction coefficients have been calculated from VΦ∘ and ΔtrsVΦ∘ values and the values have been interpreted in terms of various interactions.