Apparent molar volume and apparent molar isentropic compressibility for the binary systems {methyltrioctylammoniumbis(trifluoromethylsulfonyl)imide + ethyl acetate or ethanol} at different temperatures under atmospheric pressure

Abstract

The density (d) and speed of sound (u) for the binary systems were measured at 298.15, 303.15, 308.15, and 313.15K under atmospheric pressure. The binary systems contained the ionic liquid (IL): methyltrioctylammoniumbis(trifluoromethylsulfonyl)imide ([MOA]+[Tf2N]−). The binary systems were ([MOA]+[Tf2N]−+ethyl acetate or ethanol). The apparent molar volume, Vφ, and the apparent molar isentropic compressibility, kφ, have been evaluated from the experimental density and speed of sound data, respectively. A Redlich–Mayer equation was fitted to the apparent molar volume and apparent molar isentropic compressibility data. The partial molar volume, Vφ0, and partial molar isentropic compressibility, kφ0, of the binary mixtures have also been calculated at each temperature. The partial molar volume indicates that the intermolecular interactions for (IL+ethanol) are stronger than for (IL+ethyl acetate) at all temperatures and Vφ0 for both systems increases with an increase in temperature. The values of the infinite dilution apparent molar expansibility, Eφ0, decreases with an increase in temperature. The isentropic compressibilities, ks, increases with an increase in temperature for both binary systems. Positive kφ0, for both binary systems can be attributed to the predominance of solvent intrinsic compressibility over the solute intrinsic effect.