METHOD FOR DETERMINING THE SOLUBILITY OF SLIGHTLY SOLUBLE ELECTROCHEMICALLY ACTIVE PRODUCTS OF ELECTRODE-REACTIONS USING A ROTATING-RING-DISK ELECTRODE

A method is proposed to determine the solubility of slightly soluble ( 10(-5) - 10(-2) M) electrochemically active products produced by elect rode reactions. The products precipitate in the form of a solid phase during electrolysis. This method requires neither a prefabricated spec imen of the substance involved nor the preparation of its saturated so lution. The method is based on employing the rotating ring-disk electr ode technique to determine the ring limiting current (linear with the reaction product next-to-electrode concentration on the disc) versus t he disk electrode current, or the solution bulk concentration of the i nitial reagent. Both curves take the form of polygonal lines. The infl ection point of the polygonal lines corresponds to the saturation of t he solution layer next to the disk electrode surface with the reaction products. The solubility values of electroreduction products of a num ber of alkylpyridinium salts in alkaline water and water-alcohol solut ions of various compositions are determined.