Excess Thermodynamic Properties for Binary Mixtures of Ionic Liquid 1-Ethyl-3-methylimidazolium Ethyl Sulfate and 2-Methoxyethanol from T = (298.15 to 328.15) K at Atmospheric Pressure

The density (ρ), speed of sound (u) and refractive index (n_D) for pure [Emim][EtSO₄], 2-methoxyethanol and their binary mixtures were measured using an Anton Paar vibrating tube density and sound velocity meter (DSA 5000 M) and automatic refractometer over the whole composition range as a function of temperature between 298.15 and 328.15 K in steps of 10 K at atmospheric pressure. Experimental values were used to calculate the excess values of molar volumes (^{Vm E}), partial molar volumes (^{V¯ m E}), partial molar volumes at infinite dilution (^{V¯ m E, ∞}), isentropic compressibility (^κSE), acoustic impedance (Z^E), free length (^{Lf E}), speeds of sound (^uE), internal pressure (^πiE), free volume (^{Vf E}) and deviations in refractive index (_{Δ ϕ nD}) for the binary mixtures. These properties were fitted to a Redlich–Kister type equation to obtain the binary coefficients and the standard deviations. The negative values of ^{Vm E}, ^κSE, ^{Lf E},^αpE, and ^{Vf E} and positive values for Z^E, ^uE,^πiE, and _{Δ ϕ nD} indicate the existence of strong interactions between the components. This was further supported by IR spectroscopy analysis.