Compounds cerium

As ceric sulfate is used extensively as a volumetric oxidizing agent in quantitative analysis. Cerium compounds are used in the manufacture of glass, both as a component and as a decolorizer. 

Lanthanides is the name given collectively to the fifteen elements, also called the elements, ranging from lanthanum. La, atomic number 57, to lutetium, Lu, atomic number 71. The rare earths comprise lanthanides, yttrium, Y, atomic number 39, and scandium. Sc, atomic number 21. The most abundant member of the rare earths is cerium, Ce, atomic number 58 (see Ceriumand cerium compounds). 

Hydrolysis is very extensive in Pu(IV) solutions, less so in Pu(Ill) and Pu(VI), and least in Pu(V). The chemical properties of Pu(IV) are somewhat similar to those of Ce(IV) and U(IV) (see Cerium AND cerium compounds). The hydrolysis thermodynamics of Pu(IV) have been assessed in perchlorate solutions (105). The first hydrolysis equiUbrium is... 

Production of Cerium Derivatives. Moderately pure (90—95%) cerium compounds can be made from rare-earth chloride through oxidation with, for example, hypochlorite to produce an iasoluble cerium hydrate. The other lanthanides remain ia solutioa. The hydrate, oa calciaatioa, coaverts to Ce02. 

Ce(IV) extracts more readily iato organic solvents than do the trivalent Ln(III) ions providing a route to 99% and higher purity cerium compounds. Any Ce(III) content of mixed lanthanide aqueous systems can be oxidi2ed to Ce(IV) and the resultiag solutioa, eg, of nitrates, contacted with an organic extractant such as tributyl phosphate dissolved in kerosene. The Ce(IV) preferentially transfers into the organic phase. In a separate step the cerium can be recovered by reduction to Ce(III) followed by extraction back into the aqueous phase. Cerium is then precipitated and calcined to produce the oxide. 

The explanation appears to be related to current work on mixed-valent cerium compounds. Plutonium-americium alloys also show this behavior. Considerations based upon the plutonium atomic volume in the solids show the greatest promise of explaining this irregularity. 

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