Volumetric studies of some amino acids in binary aqueous solutions of MgCl2×6H2O at 288×15, and 308×15 K

Densities (r) of glycine, L-alanine, and L-valine in aqueous solutions of MgCl26H2O(0,1-0,8 mol kg–1) have been measured at 288,15and 308,15K. Apparent molar volumes (Vf), and limiting partial molar volumes (Vf 0) of each amino acid have been calculated. These data were combined with the earlier reported Vf 0 values of glycine, L-alanine, and L-valine in aqueous MgCl26H2O solutions at 298,15K in order to describe the temperature dependence behaviour of partial molar quantities. Group contributions to partial molar volumes have been determined for the amino acids. The trends of transfer volumes (delta V) have been interpreted in terms of solute–cosolute interactions on the basis of a cosphere overlap model. Pair and triplet interaction coefficients have also been calculated from transfer parameters.