Ionic Conductivity and Ion Association in Aqueous NaCl + Mannitol Solutions at Temperatures from 293.15 to 313.15 K

Abstract

Molar conductances for sodium chloride have been measured in the solvent system mannitol-water covering the solvent composition range from pure water to saturated aqueous mannitol at temperature from 293.15 to 313.15 K at 5 K intervals. According to the Fuoss–Justice conductance equation, limiting molar conductance \(\Lambda^{\infty }\), association constants \(K_\text{A}\), and the Walden products were obtained and their variations were in conformity with the thermodynamics study of solvent effect. The Eyring’s activation enthalpy of charge transport \(\Delta H^{\dag }\) was derived and the results have stipulated that this kinetic procedure depends only on the solvent properties. Ion association thermodynamic quantities, Gibbs energy (\(\Delta G^{ \circ }\)), enthalpy (\(\Delta H^{ \circ }\)), and entropy (\(\Delta S^{ \circ }\)) were also calculated and their interpretation were further supported by other methods. Besides, by appropriate splitting of Gibbs’ energy of association into electrostatic and non-electrostatic contributions.