The activity coefficients at infinite dilution, gamma(13)(infinity), for both polar and nonpolar solutes in the ionic liquid 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl) imidate have been determined by gas-liquid chromatography at the temperatures T = 303.15 K and T = 318.15 K. The results have been used to predict the solvent potential for the hexane-benzene separation using the calculated selectivity values. The results are compared to the gamma(13)(infinity) for similar systems found in the literature in an attempt to understand the effect that the nature of the cation has on the solute-solvent interactions. The partial molar excess enthalpies at infinite dilution values, DeltaH(1)(Einfinity), were calculated from the experimental gamma(13)(infinity) values obtained at the two temperatures.