SPECIFIC ADSORPTION OF CHLORIDE-IONS IN THE PRESENCE OF FLUORIDE IONS AT THE IDEALLY POLARIZED MERCURY-ELECTRODE

The adsorption of Cl- ions at an Hg electrode from aqueous solutions of KF + KCl was studied by measurements of the double-layer capacity. The methods of constant ionic strength and of constant ratio of the molalities of the two electrolytes were both used. In this way, it was possible to evaluate simultaneously the excess of Cl- ions and F- ions coadsorbed at the electrode. This study enabled reliable adsorption isotherms for the Cl- ion and the electrical potential drop across the electrochemical double layer, both corrected for the fluoride ion coadsorption, to be calculated. The results were shown to obey very simple patterns.