Excess volumes, mixing viscosities, and excess Gibbs energies of activation of viscous flow of the aqueous binary mixtures of the amides formamide, N-methylformamide, N,N-dimethylformamide, pyrrolidin-2-one, and N-methyl-2-pyrrolidinone were calculated from density and viscosity measurements. The values of these functions point to strong amide−water interactions with formation of a variety of aggregates, the nature of which depends on the extent of substitution of the amides; comparison of the functions of the same amides with alkan-1-ols reveal an important hydration effect. Various one-parameter and two-parameter empirical models for prediction of mixing viscosities were in good agreement with the experimental results only for the formamide−water system; none of the models predicted satisfactorily the behavior for the aqueous mixtures of both mono- and disubstituted amides.

The thermophysical properties of the (C 1 -C 11 ) alkan-1-ol/(C 1 -C 4 ) alkylbenzoate mixed solvents at atmospheric pressure and 298.15 K were studied over the whole composition range. The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties. From the experimental data, the parameters of the extended real associated solution and Prigogine-Flory-Patterson models were used to correlate and interpret the excess molar volumes. The ability of the Soave-Redlich-Kwong and Peng-Robinson equations of state combined with a set of different selected mixing rules for the correlation of the volumetric and viscometric properties was also tested. Valuable information on the behavior and governing factors of the liquid structure of the strongly nonideal solvents studied were inferred from the parameters deduced.

Density, dynamic viscosity, and refractive index of the hexane/cyclohexane/methylbenzoate ternary solvent and its binary constituents were measured at 298.15 K over the whole composition range. From the experimental measurements, excess and mixing properties were evaluated and correlated with composition using different models. The structure and interactions in the ternary solvent were analyzed starting from the experimental properties by application of the Kirkwood-Buff fluctuation theory of solutions along with the UNIFAC group contribution method for predicting activity coefficients. The local composition and excess (or deficit) number of molecules aggregated around a central one were determined using the Kirkwood-Buff integrals. The properties of the ternary system were used to test the predictive ability of several models. The volumetric properties of the binary and ternary systems were correlated and predicted with the cubic equations of state by Soave and Peng-Robinson combined with two simple mixing rules.