SOME THERMODYNAMIC FUNCTIONS OF ACTIVATION FOR VISCOUS-FLOW OF D-MANNITOL AND D-SORBITOL IN AQUEOUS-SOLUTIONS

Applying Eyring's theory of the transition state, the thermodynamic fu nctions of activation for viscous flow of binary liquid mixtures, i.e. molar Gibbs free energy, DELTA#G1,2BAR entropy, DELTA#S1,2BAR, and en thalpy, DELTA#H1,2BAR, were determined and found to be linearly depend ent on the solute mole fraction. From the linear correlation coefficie nts beta(Y) (Y = G, H or S) and die respective molar thermodynamic fun ctions of activation for viscous flow of pure solvent, the partial mol ar thermodynamic functions of activation for viscous flow of solute at infinite dilution were determined. From die partial molar thermodynam ic functions of activation for viscous flow and partial molar volumetr ic data of solute and solvent at infinite dilution, die viscosity coef ficient B and its temperature derivative were calculated and compared with those values of viscosity coefficient B obtained directly from th e concentration dependence of the relative viscosities. On the basis o f a modified Einstein viscosity law, the average hydration numbers of the solutes were determined. It was shown that the average hydration n umbers of the investigated solutes are concentration independent and s how a tendency to decrease with increasing temperature.