Studies on metal carbonate equilibria. 13. On the solubility of uranium(IV) dioxide, UO2(s)

Abstract

The equilibrium constant Kso, i.e., the solubility product for the reaction UO2(s) + 4H+ ← U4+ + 2H2O and the standard potential ∗Eo for the redox equilibrium UO22+ + 2e ←UO2(s) have been determined at 25°C in 3 M NaClO4 at acidities greater than 10-3 M by measuring the potential of platinum and uranium(IV) dioxide electrodes versus a hydrogen half-cell. The results are as follows: log Kso = -1.2 ± 0.1; ∗Eo = 0.305 ± 0.003 V (in 3 M NaClO4) and logKso = -1.6 ± 0.4; ∗Eo= 0.301 ± 0.005 V (extrapolated to zero ionic strength).