Excess enthalpies of [CnMIM][NTf2] n = (2 or 10) + ethanol or + N-methyl-2-pyrrolidone binary mixtures at 298.15 K and 0.1 MPa

Mixtures containing 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C n MIM][NTf 2 ] n = {2, 10}, + ethanol or + N-methyl-2-pyrrolidone have been investigated to determine excess molar enthalpies, H E , and excess partial molar enthalpies of components, H 1 E and H 2 E , over the entire mole fraction, x 1 , range, at 298.15 K and 0.10 MPa. Ionic liquids, ILs, were pre-treated by heating and by using activated molecular sieves. Both mixtures in ethanol are endothermic and the H i E of the components are always positive while those in NMP are exothermic and the corresponding values of H i E are negative, in the whole x 1 range. The deviations from ideality are quite significant, being the H E values at equimolar composition, H eq E ± u ; (+ 1800 ± 40 and + 2110 ± 10) J mol −1 for ethanol-containing mixtures and (− 1410 ± 10 and − 1980 ± 20) J mol −1 for NMP-containing mixtures ( u is the standard uncertainty). The values of the excess partial molar enthalpies at infinite dilution of the components, H i E, ∞ , show regular trends. The H 1 E, ∞ are always greater than the H 2 E, ∞ ; their ratio is about 1.8 for mixtures in EtOH and 2.5 for NMP-containing mixtures. The greatest thermal effects are found when the molecular compound acts as a solvent in the dissolution of one mole of IL, under extreme dilution condition.