Third Derivative of Gibbs Energy of Water-Alcohol Systems to Study the Mixing Scheme

We experimentally determined for the first time "the partial molar entropy-volume cross fluctuation density of solutei" SVδi, a third derivative of G. This quantity SVδi shows in detail how the water-like property in solution is modified as the concentration of solute increases. For this purpose, we used the laboratory-made apparatus described elsewhere. The results are shown in Figs. 1, 2, and 3 for glycerol (Gly), 1-propanol (1P), and 2-butoxyethanol (BE) aqueous systems, respectively. The figures indicate a qualitative difference between Gly (a hydrophile) and other alcohols (a hydrophobe), reflecting how the former and the latter modify molecular organization of H2O.

(by K. Yoshida & Y. Koga & A. Inaba)

	Fig. 1. SVδGly of glycerol-water system. The slope of SVδGly seems to change at points X and Y.
	Fig. 2. SVδ1P of 1P-water system. In mixing scheme I, SVδ1Pseems increasing almost linearly.
	Fig. 3. SVδBE of BE-water system. In mixing scheme I, slope of SVδBEseems to change at about XBE = 0.012.