The hydrolysis of metal ions

The hydrolysis of dioxouranium(VI) has been investigated by potentiometric titration at 250C in 0.10 mol dm-3 K[NO3]. Data treatment by advanced computer techniques indicates the presence of the species [UO2(OH)]+, [(UO2)2(OH)2]2+, [(UO2)3(OH)4]2+, [(UO2)3(OH)5]+ and [(UO2)4(OH)7]+ under the experimental conditions used: the -log βsub(pq) values of these species have been determined to be 5.50 (0.03), 5.89 (0.004), 12.31 (0.03), 16.46 (0.01), and 22.76 (0.02), respectively, the estimated standard deviations being given in parentheses. These results have been obtained for the narrow range of total initial uranium concentration of 0.185 x 10-3 to 1.853 x 10-3 mol dm-3, as required by the low value of the ionic strength used. The significance of this restricted range is discussed. (author)