Low-temperature heat capacity and standard thermodynamic functions of 1-hexyl-3-methyl imidazolium perrhenate ionic liquid

Abstract

Heat capacity for 1-hexyl-3-methyl imidazolium perrhenate ionic liquid [C6MIM][ReO4] in the temperature range from 79 to 396 K has been measured by a fully automated adiabatic calorimeter. For [C6MIM][ReO4], glass transition temperature, the melting temperature, standard molar heat capacity, enthalpy and entropy of solid–liquid phase transition were determined to be (202.164 ± 0.405) K, (226.198 ± 0.265) K, (480.702 ± 0.013) J K−1 mol−1, (15.665 ± 0.195) kJ mol−1 and (69.250 ± 0.780) J K−1 mol−1, respectively. In addition, the thermodynamic characteristics and solid–liquid phase change behavior of [C6MIM][ReO4] were compared with the ones of [C7MIM][ReO4] reported in the literature. The thermodynamic functions (HT− H298.15), (ST− S298.15) and (GT− G298.15), for the compound in the experimental temperature range were calculated.