The polarographic behaviour of oxygen gas dissolved in the molten binary KNO,-NaNO, mixture as well as that of its ionic species, OH-and OS-, has been studied by means of conventional and single sweep oscillographic polarography.
A dme was used as cathode and an Ag/AgCl electrode was the reference; on the dme oxygen gas dissolved in the melt gives rise to primary reduction waves while in presence of O*-or OH-primary oxidation waves are observed. Both waves are irreversible, the electro-oxidation being more irreversible than the reduction. The only Red species reacting in the oxidation step is demonstrated to be the hydroxyl ion, not the oxide; on the other hand both are strictly related by the equilibrium involving water, so that in presence of water is not possible to distinguish between them. The oxide and hydroxyl ions give peak limiting currents linearly proportional to the concentration in the range 1O-6-1O-8 mol/l. After determination of the transfer coefficient the diffusion coefficient of the hydroxyl ion has been determined in the temperature range 230-280°C.
R&am16--Le comportement polarographique de l'oxygkne et de ses ions dissous dans le melange de nitrates de potassium et sodium fondu a &&die avec la polarographie classique et oscillographique. L'Bectrode il goutte de mercure a Ct6 employ& comme cathode et une &&rode Ag/AgCl agit comme r&f&ence; l'oxyg6ne dissous dans le bain donne une vague cathodique primaire de reduction tandis que les ions OH-docent une vague anodique primaire d'oxydation.
L.es vagues montrent que la &action electrodique n'est pas rkversible, &ant don& que la r&action de la c&B cathodique est plus rdversible que du c&5 anodique. La seule esp6ce Clectroactive est