Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

Densities and speeds of sound have been determined for the binary mixtures containing an ionic liquid (1-butyl-3-methylpyridinium tetrafluoroborate or 1-butyl-4-methylpyridinium tetrafluoroborate) and an alkanol (methanol or ethanol) over the temperature range 293.15 K to 323.15 K. Excess volumes and excess isentropic compressibilities have been calculated and correlated. All the mixtures show negative values for these excess properties. Besides, the isothermal vapour-liquid equilibrium has been measured at T = 303.15 K and T = 323.15 K, and the corresponding activity coefficients and excess Gibbs functions have been obtained. In this case, positive excess Gibbs functions have been found. We have carried out an exhaustive interpretation of the experimental results in terms of energetic and structural effects taking also into account the thermodynamic information of pure compounds. Finally, in order to study the influence of both, the presence and the position of methyl group in the cation, we have compared the results of these systems with those obtained for the mixtures formed by 1-butylpyridinium tetrafluoroborate and methanol or ethanol.