Apparent Molar Volumes and Viscosities of Some α-Amino Acids in Aqueous Sodium Butyrate Solutions at 298.15 K

Densities and viscosities of aqueous solutions of α-amino acids (glycine, dl -alanine, dl -α-amino- n -butyric acid, dl -α-valine, and dl -α-leucine) + sodium butyrate have been measured as a function of concentrations of amino acid and electrolyte at 298.15 K. These data have been used to calculate apparent molar volumes and viscosity B -coefficients of the amino acids. The standard partial molar volumes, V ° 2, φ, standard volumes of transfer, Δ t V °, and hydration numbers of the amino acids have been determined. It has been shown that V ° 2, φ, Δ t V °, and the B -coefficient vary linearly with increasing number of carbon atoms in the alkyl chain of the amino acids, and they were split into contributions from the charged end group (NH 3 +, COO - ) and CH 2 groups of the amino acids. From the volumetric data, we found that sodium butyrate interacts strongly with the charged center of the zwitterion of the amino acids and has a strong dehydration effect on the amino acids.