LAUSR

Abstract The density of four ionic liquids 1-alkyl-2-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C2mim][NTf2] and [C4mim][NTf2]), 1-alkyl-2, 3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C2mmim][NTf2] and [C4mmim][NTf2]) have been determined with Dimethyl Carbonate (DMC) at lower concentration from 288.15 to 313.15 K at atmospheric pressure. Apparent molar volumes, Vϕ/m3·mol−1, have been calculated from the experimental densities. The effects of the methyl or methylene groups of the imidazolium cation on the above properties are discussed in deeply. The infinite dilution apparent molar volumes, Vϕ0/m3·mol−1 can be obtained from apparent molar volumes according to a Redlich-Rosenfeld-Meyer equation. The limiting apparent molar expansibility, Eϕ0/cm3·mol−1·K−1, have been calculated by the parameters from Redlich-Rosenfeld-Meyer equation. The thermal expansion coefficient, α/K−1, has also been calculated in the studied concentration range.