Ceric hydroxide

Hydroxide. Freshly precipitated cerous hydroxide [15785-09-8] Ce(OH)2, is readily oxidized by air or oxygenated water, through poorly defined violet-tinged mixed valence intermediates, to the tetravalent buff colored ceric hydroxide [12014-56-17, Ce(OH)4. The precipitate, which can prove difficult to filter, is amorphous and on drying converts to hydrated ceric oxide, Ce02 2H20. This commercial material, cerium hydrate [23322-64-7] behaves essentially as a reactive cerium oxide. 

Ceric ammonium sulfate, 5 674 Ceric fluoride, 5 674 Ceric hydroxide, 5 676 Ceric oxide, 5 670, 675 Ceric rare earths (RE), 74 631 Ceric sulfate, 5 674 Ceric sulfate method, for tellurium determination, 24 415 Cerium (Ce), 5 670-692 74 630, 63 It, 634t. See also Cerium compounds analysis, 5 679-680 color, 7 335... 

Ceric potassium nitrate is about as efficient as CAN, but ceric hydroxide and nitrate are inefTcctive in this reaction. 

Ceric hydroxide, Ce(OH)4, is not known. A hydrated oxide, probably Ce20(0H)6, forms as a yellow gelatinous precipitate when ammonia or an alkali hydroxide is added to a ceric salt. It may also be prepared by the oxidation of cerous hydroxide. It dissolves in nitric acid, forming a ceric salt, in sulfuric acid yielding a partially reduced product, and in hydrochloric acid giving cerous chloride and chlorine. 

Ceric nitrate, Ce(N03) 4, is not known as a simple salt, but double nitrates of the type Ce(N03)4 2 M N03 are formed with the alkali metals and ammonium. In aqueous solutions these salts are readily hydrolyzed, but they are the most stable ceric salts. The ammonium ceric nitrate is important in the purification of cerium. A series of double nitrates, M (N03)2 Ce(N03)4 8 H2O, is also formed, but they are less stable than the alkali double salts. When ceric hydroxide is evaporated with nitric acid, crystals of the basic salt 2 Ce0H(N03)2 9 H2O are obtained. 

Ceric fluoride, CeF4 H2O, is probably the only ceric halogen compound known in the solid form. It is a brown powder insoluble in water, prepared by adding hydrogen fluoride to ceric hydroxide. It readily forms double fluorides with the alkali metals and copper, cadmium, cobalt, nickel, and manganese. 

Ceric chloride, CeCl4, ie known only in solution. It is prepared by dissolving ceric hydroxide in concentrated HC1, but the evolution of chlorine begins at once and proceeds rapidly if the solution is hot It forms double chlorides with organic bases, such as pyridine, quinoline, and triethylamine. 

The yellow ceric hydroxide precipitate is blackened by the finely divided elementary silver. It may be that the redox reaction results in an adsorption compound because the product is incomparably blacker than if the components are produced separately and then mixed. 

The practical conclusion that can be drawn from these properties is that for ceric hydroxide formation to be avoided, we must work in strongly acidic medium in order to displace equilibria toward the left. However, in so doing, we favor the complexation phenomena with the anions of the strong acids, already evocated. There is possibly another complication. Some authors also consider the possibility of the dimerization of Ce ions in some conditions to give the species (Ce-0-Ce) +, especially in perchloric medium. 

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