Viscosity and Electrical Conductivity of Binary Mixtures of C<i>n</i>MIM-BF₄ with Ethanol at 288 K, 298 K, 308 K, and 318 K

Abstract

In a recent paper we presented experimental measurements of the dynamic viscosity and specific electrical conductivity, for binary systems of 1-alkyl-3-methyl imidazolium tetrafluoroborate, [CnMIM][BF4], with water. In this paper we complete those measurements with four systems of [CnMIM][BF4] + ethanol, the alkyl chains of the ionic liquids (ILs) used being ethyl ([EMIM][BF4]), butyl ([BMIM][BF4]), hexyl ([HMIM][BF4]), and octyl ([OMIM][BF4]). As in aqueous systems, viscosity was measured at 288.15 K, 298.15 K, 308.15 K, and 318.15 K, while conductivity was measured at those four temperatures only for selected mixtures and at 298.15 K over the whole composition range. Note that [EMIM][BF4] is only partially miscible with ethanol at the studied temperatures and atmospheric pressure (while it is completely miscible in water). We calculate viscosity deviations and molar conductivity from the original experimental data, which are compared with the scarce previously published data for similar mixtures and with the corresponding aqueous systems. Viscosity and electrical conductivity are related between them using Walden’s rule, observing an increase of the resulting value with concentration. This behavior differs from that observed in the analogous aqueous systems.