Thermodynamical Studies on Binary Systems Consisting of Polar and Non-polar Liquids. III. Caculation of the Electrostatic Part of the Thermodynamic Excess Functions due only to the Dipole of the Polar Molecule for the Binary System Composed of Polar and Non-polar Liquids according to Onsager’s Model

Abstract The electrostatic part of the excess functions for 21 binary systems consisting of polar and non-polar liquids were calculated according to Onsager’s model. The electrostatic part of the excess free energy and excess enthalpy are positive over all the concentrations for all of these systems and these quantities are unsymmetric with regard to the mole fractions x against the value at the point x = 0.5. The concentrations xmax where these quantities have maximum values, shift to a lower concentration of polar component. The larger the dipole moment of the polar components, the larger the maximum values and the shifts are. The electrostatic part of excess entropies have positive values over the whole concentration for systems consisting of a polar component of small dipole moment, but for those consisting of one with a larger dipole moment, these quantities take negative values for a high concentration of polar component, but take positive values for a low concentration range. The electrostatic part of van Laar coefficients is also calculated and these values increase with the decrease of concentration of polar component.