- 作者： --
- 作者服務機構： Department of Chemistry, Jamia Millia Islamia (Central University), New Delhi-110025, India
- 中文摘要： Densities, r, viscosities, h, and refractive indices, nD, of glycine (Gly) (0.1 - 0.5 M) in aqueous 1,2-ethanediol (1,2-EtD), 1,2-propanediol (1,2-PrD), and 1,3-butanediol (1,3-BuD) (30% v/v) were measured at 298, 303, 308, and 313 K. Experimental values of r and h were used to calculate partial molar volumes, f0v, partial molar volumes of transfer of Gly from water to aqueous diol solutions, f0v(tr), Falkenhagen and Jones - Dole coefficients, A and B, respectively, free energies of activation of viscous flow, Dm0*1 and Dm0*2, per mole of solvent and solute, respectively, enthalpies, DH* and entropies, DS* of activation of viscous flow. Large positive values of f0v, 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 f0v(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 solute-solvent 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 dB/dT values suggest the structure-breaking nature of Gly in diol + water mixtures. The observed values of Dm0*2 fall in the sequence: 1,2-EtD > 1,2-PrD > 1,3-BuD which, like f0v and Sv*, reinforce that Gly-diol interaction decreases with subsequent addition of CH2 group in diols. The trends in the variation of DH* and DS* 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.
- 英文摘要： --
- 中文關鍵字： Densities; Viscosities; Refractive indices; Glycine; Aq diols; Interactions.
- 英文關鍵字： --
