Volumetric properties and molecular interactions of binary mixtures imidazolium acetates-ethanol at 293.15 K

Over the full molar fraction range and at 293.15 K, the densities of binary systems 1-methylimi-dazolium acetate([Mim]Ac)/1, 3-dimethylimidazolium acetate([Mmim]Ac)/1-ethyl-3-methylimidazolium acetate([Emim]Ac)(1)-ethanol(EtOH)(2) were measured by pycnometer method. The apparent molar volumes of [Mim]Ac/[Mmim]Ac/[Emim]Ac and EtOH, and the excess molar volumes of the binary mixtures were calculated. The relations of apparent molar volumes and molar fractions were fitted by three-parameter polynomials, from which, the limiting partial molar volumes and molar volumes were extrapolated. For [Mim]Ac/[Mmim]Ac/[Emim]Ac and EtOH, the values of molar volumes from extrapolation and measurement are consistent with each other within ±0.07 and ±0.04 cm³/mol, respectively. The solvation coefficients at infinite dilutions of [Mim]Ac/[Mmim]Ac/[Emim]Ac and EtOH were calculated. The Redlich-Kister equation was used to fit the excess molar volumes and molar fractions. Finally, the solute-solvent pairs' molecular interactions were discussed in terms of the limiting partial molar volume, the difference of molar volume and limiting partial molar volume, the solvation coefficients at infinite dilutions, and the excess molar volume. The results show that the sequence of molecular interaction at infinite dilutions of [Mim]Ac/[Mmim]Ac/[Emim]Ac is [Mim]Ac-EtOH>[Mmim]Ac-EtOH>[Emim]Ac-EtOH, and that at infinite dilutions of EtOH and [Mim]Ac/[Mmim]Ac/[Emim]Ac of x₁=0.15-0.95, the sequence is [Emim]Ac-EtOH>[Mmim]Ac-EtOH>[Mim]Ac-EtOH.