Representation of electrical conductances for polyvalent electrolytes by the quint-viallard conductivity equation. Universal curves of limiting conductances and walden products of electrolytes in mixed solvents. Part 5. Symmetrical 2:2, 3:3 and unsymmetrical 1:2, 2:1 and 1:3 type electrolytes

摘要

Conductivities of symmetrical and unsymmetrical electrolytes of 2:2, 3:3, 1:2, 2:1 and 1:3 types in ethanol-water and the 1,4-dioxane-water mixtures were analyzed using the Quint-Viallard conductivity equation and taking into account the ion association effect. The molar limiting conductances and the ion association constants were reexamined for various multivalent electrolytes. One non-aqueous system, methanol-ethylene glycol mixtures, was also considered. The limiting conductances were also examined in the framework of universal curves of limiting conductances and the excess Walden products introduced by the author. These new concepts in the analysis of conductance data allow the estimation of values of limiting conductances of electrolytes or ions, to give an indication about the quality of the conductivity measurements and the type of interactions expected in the systems. It was found that for any type of electrolyte only one universal curve of limiting conductances exists. In the water-rich mixtures, attractive interactions (structure-making effects) are expected when electrolytes are added to mixtures with ethanol or with 1,4-dioxane. In contrast, in ethylene glycol-methanol-rich mixtures repulsive interactions (structure-breaking effects) are more likely.