Study on Enthalpy and Molar Heat Capacity of Solution for the Ionic Liquid [C₂mim][OAc] (1-Ethyl-3-methylimidazolium acetate)

Abstract

An acetic acid ionic liquid (AcAIL) [C 2 mim][OAc] (1-ethyl-3-methylimidazolium acetate) was prepared by the neutralization method. Using the solution-reaction isoperibol calorimeter, molar enthalpies of solution, Δ sol H m, for the ionic liquid [C 2 mim][OAc] with different molalities were measured in the temperature range from (288.15 to 308.15 ± 0.01) K with an interval of 5 K. In terms of Archer’s method, the standard molar enthalpies of solution, Δ sol H m θ, for [C 2 mim][OAc] were obtained in the temperature range of (288.15 to 308.15 ± 0.01) K. Plotting Δ sol H m θ against ( T – 298.15) K, a good straight line was obtained, with the slope of the line being the standard molar heat capacity of solution, Δ C p,m θ = 411 J·K –1 ·mol –1, for [C 2 mim][OAc], and the specific heat capacity of solution, Δ C p θ = 2.4 J·g –1 ·K –1, was also obtained.