A powerful new correlation technique is introduced. It is based on the theoretical and experimental results of atomic spectroscopy, and it is shown to be generally applicable for intraseries correlations of various physical and chemical properties, such as oxidation potentials, first electron-transfer absorptionband energies, and first f-d absorption-band energies of the compounds and complexes of the lanthanide and actinide series. For many of the members of these series representative values of some of these properties were available from the literature; for others new measurements were made, so that sufficient data are available to provide a test of the general validity of the theory, and hence, to calculate many of these properties for all the members of both series. The most important new results of this work are the determination or verification of the following standard oxidation potentials: £°Sm(H-III) = +1.55, E°Eu(lI--) = +0.35, £°Tm(II-ffl) = +2.3 ± 0.2, E°Yb(H-III) = +1.15, £°Am(II-IH) = +2.3 ± 0.2, E°Es(II-III) = +1.2 ± 0.2, £°Fm(]l-III) = +1.1 ± 0.2, £°Md(II-III) = +0.15, and £°No(IT-III) = -1.45, each in volts relative to the standard oxidation potential of the normal hydrogen electrode. try of the Transuranium Elements, Sept 4-8, 1972, Moscow.

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Plutonium / ModelingSummary The solubility of Pu(OH) 3 is determined in deionized water and in chloride brines that contained Fe powder to maintain Pu in the Pu(III) oxidation state. The presence of aqueous Pu(III) was verified experimentally. The solubility of Pu(OH) 3 is several orders of magnitude greater in brines than in deionized water at the same hydrogen ion concentration. The logarithm of the equilibrium constant, extrapolated to zero ionic strength from experiments in deionized water, for the reaction Pu(OH) 3 Pu 3 + + 3 OH" is determined to be -26.2 ± 0.8. The data for solubility in brines are interpreted in terms of the ion-interaction model of Pitzer and coworkers for the excess solution free energy. These solubility data can be explained to within experimental error by a relatively simple ion-interaction model that includes only binary interactions between Pu 3+ and Cl~. Ion pairs or ternary interaction parameters for Pu 3+ were not required in order to predict the solubility of Pu(OH) 3 in natural chloridedominated brines at -log[H + ] values of <9, where brackets represent concentration.