In this work, we report the experimental values of the excess quantities H m E and V m E and the isobaric equilibrium data (VLE) at 101.32 kPa for the four mixtures of alkyl methanoates (methyl to butyl) and hexane. The results indicate that for these four mixtures (∂H m E /∂T) p > 0 and(∂V m E /∂T) p > 0. VLE data were found to be thermodynamically consistent with the Fredenslund method. All the binary mixtures presented here, except for the system (butyl methanoate + hexane), present a minimum-boiling temperature azeotrope with coordinates (x az , T az /K), (0.832, 302.62) for (methyl methanoate + hexane), (0.703, 323.32) for (ethyl methanoate + hexane), and (0.283, 339.10) for (propyl methanoate + hexane). Simultaneous correlations performed with the VLE data and excess enthalpies using a simple polynomial model, with temperature-dependent coefficients, produced acceptable estimations. Application of the UNIFAC model in the versions of Hansen et al. (Ind.

In this work, we report the experimental values of densities, viscosities, and refractive indices at 298.15 K and atmospheric pressure for the ternary and associated binary mixtures of tris(2-hydroxyethyl) methylammonium methylsulfate + water + ethanol. Excess molar volumes and viscosity logarithm variations have been calculated from the density and viscosity of these mixtures. The excess properties have been fitted with two polynomial models that produced acceptable correlations.

a b s t r a c tThis work presents experimental mixing properties, h E and v E , at several temperatures and the isobaric vapor-liquid equilibria (iso-p VLE) at 101.32 kPa for four binaries containing pentane and four alkyl (methyl to butyl) methanoates. Particular conditions are established to work with these solutions with highly volatile compounds, especially for the case of methyl methanoate + pentane system, for which a continuous feeding device is designed and constructed for measuring the densities. The mixing processes of the compounds chosen give rise to high values for the excess properties and also for the activity coefficients, since in addition to the known effects that arise in the binaries ester + alkane, in this case the associative effects caused by the HCOO-group, which diminish with increasing methanoate chain length are also relevant. The change in temperature produces slopes of opposite signs for the mixing properties, being ∂v E /∂T p < 0 and ∂h E /∂T p > 0. The systems comprised of methyl and ethyl methanoate with pentane present azeotropes with coordinates (x az ,T az /K) situated at (0.558, 293.9) and (0.218, 306.5), respectively. The estimation of these coordinates and the iso-p VLE by the UNIFAC method are acceptable but do not give good predictions of the h E even less so for the LLE of the methyl methanoate + pentane system. For this binary, experimental data of all the properties are correlated with a mathematical procedure described using two models, one developed by us, and an extended form of the NRTL model. The latter does not represent the LLE data but shows the properties of isobaric equilibria, with acceptable results, while the proposed model, in addition to representing the binodal curve, gives a good representation of the v E and of these properties derived from excess Gibbs function.

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