Transfer Properties of Amino Acids from Water to Aqueous Sodium Sulfate Solutions at 298.15 K

Enthalpies of solution and densities of glycine, l-alanine, and l-serine in aqueous solutions of Na2SO4 were measured at 298.15 K. Transfer enthalpies (Δtr H) and transfer partial molar volumes (Δtr V ϕ 0) of amino acids from water to aqueous solutions of Na2SO4 were derived. The Δtr H of l-alanine are positive, and the Δtr H of glycine and l-serine are negative. The transfer volume of all three of the amino acids are positive. The relative order in the negative value of Δtr H of amino acids in the same concentration of Na2SO4 is l-serine < glycine < l-alanine, whereas the sequence of Δtr V ϕ 0 is l-serine > glycine > l-alanine. The results are discussed in terms of the cosphere overlap model.