The study of solute–solvent interactions in 1-ethyl-3-methylimidazolium tetrafluoroborate + 2-ethoxyethanol from density, speed of sound, and refractive index measurements

Abstract

Physical properties, such as density (ρ), speed of sound (u), and refractive index (nD) for pure [Emim][BF4], 2-ethoxyethanol and their binary mixtures, are measured using Anton Paar vibrating tube density and sound velocity meter (DSA 5000 M) and automatic refract meter 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 molar volumes (\( V_{\rm m}^{\rm E} \)), excess values of partial molar volumes (\( \overline{V}_{{\text m}}^{\rm E} \)), partial molar volumes at infinite dilution (\( \overline{V}_{{\text m}}^{\rm E ,\infty } \)), isentropic compressibility (\( \kappa_{\rm s}^{\rm E} \)), acoustic impedance (ZE), free length (\( L_{{\text f}}^{\rm E} \)) and deviations in speeds of sound (ud), and refractive index (\( \Delta_{\emptyset } n_{\rm D} \)) for the binary mixtures. These excess/deviation properties are fitted to the Redlich–Kister-type equation to obtain the binary coefficients and the standard errors. A qualitative analysis of intermolecular interactions between the liquids in study is analyzed on the basis of the measured and the derived properties.