Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

The densities, q, speeds of sound, u, and molar heat capacities, CP, of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (i) + 1-butyl-3-methylimidazolium tetrafluoroborate (j); 1-butyl-3-methylimidazolium tetrafluoroborate (i) + 1-ethyl-3-methylimidazolium tetrafluoroborate (j) and 1-butyl-2,3-dimethylim idazolium tetrafluoroborate (i) + 1-ethyl-3-methylimidazolium tetrafluoroborate (j) mixtures at temperatures (293.15, 298.15, 303.15, 308.15) K and excess molar enthalpies, HE, for the same mixtures at temperature (298.15) K have been measured over entire range of mole fraction under atmospheric pressure. Using experimental data, excess molar volumes, VE, excess isentropic compressiblities, jES , excess molar enthalpies, HE and excess molar heat capacities, CEP have been determined. The VE, jES , HE and CEP data have been fitted to Redlich-Kister equation to estimate the binary adjustable parameters and standard deviations between experimental and calculated values. The topology of the constituent molecules (Graph theory) has been utilized to predict VE, jES , HE and CEP data of the studied mixtures. The comparison of VE, jES , HE and CEP values determined by Graph theory with their corresponding experimental values lends additional support to the proposed molecular entities existing in mixtures along with various processes involved in the (i + j) mixtures formation. Further, IR studies and quantum mechanical calculations support the presence of proposed molecular entities in the studied mixtures.