Bismuth , aqueous solution chemistry

Only for bismuth can it be said that there is an extensive true cationic chemistry. Aqueous solutions contain well defined hydrated cations but there is no evidence for the simple aquo ion [Bi(H20) ]3 +, In neutral perchlorate solutions the main species is [Bi606]6+ or its hydrated form, [Bi6(OH)12]6+, and at higher pH [Bi606(0H)3]3+ is formed. The [Bi6(OH)12]6+ species contains an octahedron of Bi3+ ions with an OH- bridging each edge. 

Cerium (IV) in solution is obtained by treatment of Ce111 solutions with very powerful oxidizing agents, for example, peroxodisulfate or bismuthate in nitric acid. The aqueous chemistry of CeIV is similar to that of Zr, Hf, and, particularly, tetravalent actinides. Thus Ce gives a phosphate insoluble in 4 M HN03 and an iodate insoluble in 6 M HN03, as well as an insoluble oxalate. The phosphate and iodate precipitations can be used to separate Ce from the trivalent lanthanides. Ce is also much more readily extracted into organic solvents by tributyl phosphate and similar extractants than are the Lnm lanthanide ions. 

Bismuth nitrate is identified in several sources as a form of bismuth white (. v.) (Harley, 1982 Colour Index, 1971). However, the aqueous chemistry of bismuth (Bp ) in the presence of the nitrate ion gives rise to a range of compoimds from acid solutions, for example, it is possible to form Bi(N03)3.5H20, while treatment of Bi203 with HNO3 gives basic salts such as Bi0(N03) and Bi202(0H)(N03) (Cotton et al, 1999). 

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