Uranous bromide

An interesting case of selective oxidation in solution is given hy Jones,2 who has studied the absorption spectrum of a solution of uranous bromide in a mixture of water and methyl alcohol. Addition of potassium perchlorate effects an alteration in the absorption bands m such a manner as to show that the portion of the uranous salt combined with the methyl alcohol has undergone no change, whilst that united with the water has become oxidised. 

Uranium Trihromide, UBr, is obtained by reduction of uranous bromide in a stream of hydrogen. It yields dark brown needles with properties similar to those of the trichloride (see p. 293). 

Uranyl Bromide, UOgBra.— Wlien uranous oxide is heated in a current of bromine vapour a mixture of uranyl bromide and uranous bromide is formed. The former can be exteacted with ether, and obtained as j-ellou-ish-green fluorescent needles by evaporation of the solution. It is obtained in aqueous solution by the action of bromine water on uranous oxide, or of hydrobromic aeid on uranie oxide yellow needles of the heptahydrate, U03Br2.7H20, separate on concentrating the solution. Uranyl bromide is very deliquescent and is decomposed in moist air to hydrated uranic oxide and hydrobromic... 

A bricli-red variety of uranous oxide has been obtained by ealcining uranyl bromide in the air. It is very stable at high temperatures, and is converted to the black modification by heating in hydrogen without any appreciable loss of oxj gen. 

Pure uranous compounds may be prepared by precipitating U(OH)4 from aqueous solution with ammonium hydroxide and dissolving the precipitate in the appropriate acid. Uranous sulfate, the most common salt, is soluble in water, as are the chloride, bromide, and iodide. Uranous nitrate is unstable, gradually undergoing oxidation to uranyl nitrate with liberation of oxides of nitrogen. 

CaU04 CALCIUM URANATE 474 CeBr3[g] CERIUM BROMIDE (GAS) 511... 

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