POLAROGRAPHY OF URANIUM: III. URANIUM(VI) IN FLUORIDE MEDIA

Abstract

The uranium(VI) and (V) polarographic waves were studied in chloride and perchlorate supporting electrolytes of 0.1 M to almost neutral acidities and containing 0 to 100 fold excess of fluoride. The concentrations of the uranium(VI)–fluoride species (UO2Fn+2−n, n = 1 − 4) were calculated and it is shown that the first two species, UO2F+ and UO2F2, are either reduced reversibly at the D.M.E., or dissociate rapidly to the uncomplexed ion, UO2++, which is known to reduce reversibly. The UO2F4− species, and possibly also UO2F3− is reduced irreversibly, and the rate constant of the electron transfer process, kf°, and the transfer coefficient, α, were calculated by two methods. The electrode reaction is proposed as UO2Fn+2−n+e− = UO2++nF−. The rate of disproportionation of uranium(V) was found to depend upon the F/U ratio, and the rate constants for the reaction were calculated.