Low-temperature heat capacities and the thermodynamic functions of ionic liquids 1-heptyl-3-methyl imidazolium perrhenate

Low-temperature heat capacities of the 1-heptyl-3-methyl imidazolium perrhenate ionic liquids have been measured by a high-precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. In this report, the standard molar heat capacity was determined to be 679.438 J K −1 mol −1 . The melting temperature at 207.873 ± 0.374 K has been discovered by the heat-capacity curve. The experimental values of molar heat capacities were fitted to two polynomial equations of heat capacities ( C p,m ) by least square method. Meanwhile, the thermodynamic functions ( H T − H 298.15 ), ( S T − S 298.15 ), and ( G T − G 298.15 ) were also calculated in the temperature range from 298.15 to 400 K with the interval of 5 K.