Thermodynamics of the interaction of HCl with D-galactose in water at 278.15–318.15 K

Abstract

Thermodynamic parameters of the interaction of HCl with D-galactose in water have been determined from electromotive force measurements at 10 K intervals from 278.15 to 318.15 K. Standard Gibbs energies of transfer of HCl from water to aqueous solutions of 5, 10, 15 wt.% D-galactose were evaluated. Comparison of pair interaction parameters of HCl–D-galactose was made with those of HCl–D-glucose and HCl–D-arabinose. The difference between these parameters was interpreted in terms of the stereochemistry of these monosaccharides. An enthalpy–entropy compensation has been observed with the pair interaction parameters for the HCl–sugar–water systems at each given temperature studied. The salting constants, k_S, of D-galactose, D-glucose, D-fructose, D-arabinose, and sucrose by HCl in water were calculated from (a) the Debye–MacAulay theory (DMT); (b) Conway–Desnoyers–Smith theory (CDST); (c) the internal pressure theory developed by McDevit–Long (IPT); (d) the scaled particle theory (SPT). The results show that the calculated values of k_S are reasonably in agreement with the experimental ones.