Effect of Temperature on Volumetric and Viscometric Properties of Homologous Amino Acids in Aqueous Solutions of Metformin Hydrochloride

Density (ρ) and viscosity (η) are measured for glycine, DL-α-alanine DL-α-valine, and DL-α-leucine in 0.05, 0.10, 0.15 and 0.20 mol·L−1 aqueous metformin hydrochloride at 308.15, 313.15 and 318.15 K. The measured values are used to estimate some important parameters, such as partial molal volume Vϕ, standard partial molal volume V0ϕ, transfer volume ΔV0ϕ, hydration number nH, the second derivative of infinite dilution of partial molal volume with respect to temperature, viz., ∂2V0ϕ/∂T2, viscosity B-coefficient, variation of B with temperature, viz., dB/dT, free energy of activation per mole of solvent Δμ10* and solute of the amino acids. These parameters are interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution. In addition, V0ϕ, ΔV0ϕ, viscosity B-coefficient, ΔB and Δμ20* are split into group contributions (NH3+COO−) and —CH2 of the amino acids using their linear correlation and their behavior is discussed.