Polarography

About: Polarography is a research topic. Over the lifetime, 4772 publications have been published within this topic receiving 75478 citations.

An Analysis of the Voltammetric Adsorption Waves of Methyl Viologen

Abstract: The electrochemical behavior of 1,1′-dimethyl-4,4′-bipyridinium dichloride (methyl viologen, MV) is complicated with the strong adsorption of both the oxidized (MV2+) and the reduced (MV+·) forms of MV on a mercury electrode. MV2+ adsorbs on the electrode with a flat orientation at more positive potentials than the potential of zero charge of the mercury electrode. MV+· adsorbs on the electrode with a vertical orientation at more negative potentials than the formal potential of the MV2+⁄+· couple, (E0′)MV. It is probable that the change in the orientation of the adsorbed MV+· from flat to vertical with the increase in the MV+· concentration in the vicinity of the (E0′)MV leads to a strongly attractive interaction between the adsorbed MV+· molecules and a sharp voltammetric adsorption peak results at higher concentrations of MV2+.

Synthesis and electrochemical properties of heteropolymolybdates

Abstract: The beta form of 12-molybdosilicic acid was prepared and isolated as a yellow hygroscopic solid from a 1:1 mixture of water-dioxane. The identity of the beta- isomer was established polarographically and spectrophotometrically. The range of stability of the beta-isomer as a function of hydrogen ion concentration was determined. In addition, techniques were developed for preparing, in pure form, several heteropoly compounds used for polarographic and conductivity measurements. The solvolytic stability, electrolyte strength and oxidation-reduction behaviour of several heteropoly compounds were determined by pH, conductivity, and polarographic measurements. Heteropolymolybdate oxidation—reduction behaviour and stability in solution were examined by direct current and alternating current polarography and cyclic voltammetry in aqueous and water-dioxane solutions. The reduction of the anions proceeds in several steps for which the half-wave potentials were determined. Conductivity and pH measurements on the heteropoly acids H4 [PMo11V040]and H5 [PMo10V2O40]at 25 °C in aqueous solution, and in mixed oxygen-containing solvents, show that the vanadium compounds exhibit behaviour typical of unsymmetrical strong electrolytes in oxygen-containing solvents and are stable in these media.