Zur Kenntnis der Glaselektrolyse

Interfacial tension of electrolyte solutions

“…Appealing to the Gibbs adsorption isotherm [8], it is evident that the depletion of solute near the interface results in an increase of surface tension. Furthermore, the experimental observation that for small concentrations this increase depends only weakly on the ionic size [1,2,3,4,5], suggest the existence of a universal limiting law, similar to the one obtained by Debye and Hückel for bulk properties of electrolyte solutions [7]. Indeed, the calculation of Onsager and Samaras (OS) seems to confirm such a limiting law [9].…”

“…Some extra care, however, has to be taken to account for the strong correlations between the cations and the anions, which result from an increased ionic charge [10,11]. In view of the experimental observation that for small concentrations of electrolyte the excess surface tension depends only weakly on the ionic size [1,4,5], to simplify the calculations we shall treat ions as point-like. The solvent will be modeled as a uniform dielectric medium.…”

“…It has been known for almost a century that aqueous solutions of inorganic salts have greater surface tension than pure water [1]. An explanation of this effect was advanced by Wagner [6] in 1924 on the the basis of the theory of strong electrolytes, which was introduced only a year earlier by Debye and Hückel [7].…”

Thermodynamic quantities of surface formation of aqueous electrolyte solutions X. Aqueous solution of 2:1 valence-type salts

“…From the beginning of the study of the surface of simple salt solutions, numerical values of (d/dm) has been used as an empirical parameter characteristic of each salt or group of salts. The value roughly 1.5 mN m -1 mol -1 Kg of (d/dm) is common for uni-univalent electrolytes, and about twice of this value is generally adapted for salts of divalent cations [6]. Early works are reviewed by Randles, who described the Onsager and Samaras' image force theory, and summarized that equivalent concentrations of many different salts of the same valence type gave almost identical increments of surface tension at sufficiently low concentration region [1].…”

“…For high valence type electrolytes, as predicted by theory that Coulombic force may explain the surface tension increments, there seems to be no doubt that d/dm of electrolytes with divalent and trivalent cation yield about twice and triple the magnitude of that observed for univalent cation [6]. However, it is still uncertain whether their anion plays a significant effect on surface tension of solutions than cation or not.…”