Volumetric and viscometric study of amino acids in aqueous sorbitol solution at different temperatures

Densities ( ρ ) and viscosities ( η ) of glycine, l -alanine, l -valine, l -threonine and l -arginine in (0.2, 0.4, 0.6, 0.8 and 1.0)   mol   ·   kg −1 aqueous sorbitol solutions have been measured at T   =   (293.15, 303.15, 313.15 and 323.15)   K under atmospheric pressure. The apparent molar volume ( V φ ) and the limiting partial molar volumes of amino acids ( V φ 0 ) were calculated through the density data. And the limiting partial molar volumes of transfer (Δ tr V φ 0 ) and interaction coefficients V ab , and V abb were also determined. The extended Jones–Dole equation was used to correlate the viscosities in order to obtain viscosity B -coefficient and the free energies of activation per mole of solvent (Δ μ 1 0≠ ) and solute (Δ μ 2 0≠ ). The limiting partial molar volume of transfer and the free energies of activation per mole of both solvent (Δ μ 1 0≠ ) and solute (Δ μ 2 0≠ ) were discussed on the basis of the co-sphere overlap model and transition state theory, respectively. The hydration number of amino acids was computed using the obtained limiting partial molar volume and viscosity B -coefficient. Additionally, the group contribution method was applied to determine the respective contribution of (NH 3 + , COO − ), CH 2 , OH and CNHNHNH 2 to V φ 0 and B -coefficient.