Excess molar enthalpies for [emim][BF4]+pyrrolidin-2-one or 1-methyl pyrrolidin-2-one+pyridine or water mixtures

Excess molar enthalpies, H ijk E of ternary 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + Pyrrolidin-2-one (j) + Pyridine or Water (k); 1-ethyl-3-methylimidazolium tetrafluoroborate (i) 1-methyl pyrrolidin-2-one (j) + Pyridine or Water (k) and HE of Pyrrolidin-2-one (i) + Pyridine or Water (j); 1-methyl pyrrolidin-2-one (i) + Pyridine (j); 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + Water (j) mixtures have been measured over entire mole fraction range at 298.15 K. The H ijk E value for 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + Pyrrolidin-2-one (j) + Water (k); 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + 1-methyl pyrrolidin-2-one (j) + Pyridine or Water (k) are positive over whole range of composition and for 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + Pyrrolidin-2-one (j) + Pyridine (k) mixture, the sign of H ijk E values varies with change in composition of the components. The observed data have been analyzed in terms of (i) Graph; and (ii) Prigogine–Flory–Patterson (PFP) theories. Results indicate that HE and H ijk E values obtained by Graph theory are in good agreement with experimental data. The PFP theory correctly predict sign as well as magnitude of HE values for the binary mixtures. However, theory fails to predict the sign of H ijk E values for the ternary mixtures.