The volumetric properties of aqueous solutions containing non-electrolytes have been determined by density measurements in the temperature range 0.5-25 "C. Linear polyols CH,OH(CHOH),CH,OH with n = 2-4 (n = 4 has three diasteroisomers), myo-inositol and t-butylurea have been studied.Vz and the coefficients of the virial expansion of the excess property (V,,, V,,, . . .) have been evaluated and interpreted in terms of solute-solute and solute-solvent interactions with the aid of the enthalpy and free-energy data where known. The theory of group contributions has been used to interpret the V,, values of those linear polyols not exhibiting solute-solute interactions at 25°C. The results confirm the relation between the signs of the enthalpic and volumetric contributions also found for other kinds of non-electrolyte.

Partial molar volumes at infinite dilution, c, and pairwise contributions to the volume, v,, , are computed from density measurements of aqueous solutions of some polyhydroxylated compounds. A modified group-additivity approach is proposed to evaluate with precision the q values of positional isomeric compounds, when the c values of the first members of a few homologous series are known. The v, , values are correlated to the corresponding q values, confirming a previous hypothesis (C. Cascella, G. Castronuovo, V. Elia, R. Sartorio and S.

Enthalpies of dilution in water of binary aqueous solutions of n-diols of increasing alkyl chain length are performed using a flow microcalorimeter. The pairwise enthalpic coefficients of these hydrophobic solutes depend mainly on the mutual positions of the -OH groups in the molecule. A rationalization of the excess enthalpies of positional isomers is attempted

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