Thermodynamic investigations of excess heat capacities of ternary liquid mixtures containing [Bmmim][BF4] + [Bmim][BF4] or [Emim][BF4] + cyclopentanone or cyclohexanone

In this paper, molar heat capacities (CP)123 data of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, [Bmmim][BF4] (1) + 1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF4] or 1-ethyl-3-methylimidazolium tetrafluoroborate, [Emim][BF4] (2) + cyclopentanone or cyclohexanone (3) mixtures have been reported over the entire range of composition at (293.15, 298.15, 303.15, 308.15) K using micro-differential scanning calorimeter (Model—μDSC 7 Evo). The results have been utilized to calculate excess heat capacities CPE123\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left( {C_{\text{P}}^{\text{E}} } \right)_{123} $$\end{document} values of the studied mixtures. The CPE123\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left( {C_{\text{P}}^{\text{E}} } \right)_{123} $$\end{document} data have been fitted to Redlich–Kister equation to obtain ternary coefficients and standard deviations. The Moelwyn–Huggins concept of interaction between the surfaces of constituents of binary mixtures (Huggins in J Phys Chem 74:371–378, 1970) containing ionic liquid as one of the component has been extended to obtain expression (Graph theory) for CPE123\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left( {C_{\text{P}}^{\text{E}} } \right)_{123} $$\end{document} of ternary mixtures. The comparison between experimental and estimated values (Graph theory) suggests that while 1-butyl-2,3-dimethylimidazolium tetrafluoroborate or 1-butyl-3-methylimidazolium tetrafluoroborate or 1-ethyl-3-methylimidazolium tetrafluoroborate exists as monomer, cyclopentanone or cyclohexanone exists as mixture of open and cyclic dimer. The results further support the various processes involved in the formation of present mixtures. The CPE123\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left( {C_{\text{P}}^{\text{E}} } \right)_{123} $$\end{document} values have also been tested in term of modified Flory’s theory.