Volumetric, Viscometric, and Refractive Index Behaviour of Glycine in Aqueous Diols at Different Temperatures

298, 303, 308, and 313 K. Experimental values of and were used to calculate partial molar volumes, 0 v, partial molar volumes of transfer of Gly from water to aqueous diol solutions, 0 v(tr), Falkenhagen and Jones Dole coefficients, A and B, respectively, free energies of activation of viscous flow, 0* 1 and 0* 2, per mole of solvent and solute, respectively, enthalpies, H * and entropies, S * of activation of viscous flow. Large positive values of 0 v,and an increasing value of Sv*, for all the three mixtures at each temperature suggest the presence of strong solute-solvent interaction, and this interaction decreases as the size of alkyl moiety increases from 1,2-EtD to 1,3-BuD. Positive 0 v(tr) values tend to decrease with increasing the number of CH2 group, thereby indicating that the electrostriction effect in diols follows the sequence; 1,2-EtD > 1,2-PrD > 1,3-BuD. Small A values, with large values of B, are indicative of weak solute-solute and strong solutesolvent interactions that operate in the present systems, and that the magnitudes of B are in the sequence: 1,2-EtD > 1,2-PrD > 1,3-BuD and, thus, the sequence represents the strength of interaction between Gly and diol molecules. Moreover, positive B/T values suggest the structure-breaking nature of Gly in diol + water mixtures. The observed values of 0* 2 fall in the sequence: 1,2-EtD > 1,2-PrD > 1,3-BuD which, like 0 v and Sv*, reinforce that Gly-diol interaction decreases with subsequent addition of CH2 group in diols. The trends in the variation of H * and S * with Gly concentration also reveal the presence of significant solute-solvent interaction in all three systems. An almost linear increase in RD with an increasing amount of Gly reveals that Gly tends to increase the polarizability of the aqueous-diol molecules under study. The variation of all these parameters with concentration of Gly and with temperature suggests the presence of strong solute-solvent interaction, which decreases as the size of alkyl moiety in diols increases from 1,2-EtD to 1,3-BuD.