Thermophysical studies of protonated and deprotonated glycine in aqueous sodium acetate buffer solutions at different temperatures

Abstract

Interactions of glycine in water and in (0.10, 0.50 and 1.00) mol kg−1 aqueous sodium acetate buffer solutions of pH(1.00 and 12.40) have been investigated at different temperatures, T(K) = (298.15-318.15). Densities, 𝜌 and viscosities, 𝜂 of glycine in water and in aqueous sodium acetate buffer solutions have been measured. The obtained density data have been used to calculate apparent molar volume, 𝜙𝑣, limiting partial molar volume, 𝜙𝑣𝑜, limiting partial molar volumes of transfer,Δ𝑡𝑟𝜙𝑣. Viscosity B-coefficient, viscosity B-coefficient of transfer, Δ𝑡𝑟𝐵, activation free energies per mole of the solute,Δ𝜇2𝑜# and solvent, Δ𝜇1𝑜# have been calculated from viscosity data. Further, second order derivative of partial molarexpansion coefficient and dependence of 𝑑𝐵𝑑𝑇 coefficients on temperature is useful in measuring the structure making and breaking behaviour of solute in these systems. Pair and triplet interaction coefficients for both the properties were also calculated. Thus, the results obtained from volumetric and viscometric studies are of considerable importance to identify different type of interactions (i.e. H-bonding, van der Waals interactions) in these systems.