Uranyl sulphate

According to C. F. Barwald and A. Monheim (1835), the decomposition is accelerated by the presence of organic substances. J. Milbauer tried the effect of thirty-two metal chlorides of sodium tungstate and molybdate of uranyl sulphate and of sulphuric, selenic, arsenic, and boric acids on the photo-decomposition of chlorine water, and found. that none accelerated but that most retarded the action. Chlorine catalyzes the decomposition of bromine water and bromine, chlorine water while iodine does not accelerate, but rather retards the reaction, probably by forming relatively stable iodine compounds. A. Bcnrath and H. Tuchel found the temp, coeff. of the velocity of the reaction with chlorine water between 5° and 30° increases in the ratio 1 1 395 per 10°. 

Uranyl Platinocyanide, U02.Pt(CN)4.4(or 5)H20, has been prepared 6 by double decomposition of solutions of uranyl sulphate and barium platinocyanide. The green, filtered solution, upon evaporation at room temperature in a desiccator, deposits red crystals possessing a strong green metallic reflection. 

Photocells may be used in place of thermopiles. Still other devices are chemical actinometers, which are merely gas mixtures or solutions sensitive to light. When radiation impinges upon these, a chemical reaction ensures whose extent is determined by the amount of energy absorbed. The most common of these is the uranyl oxalate actinometer, consisting of 0.05 molar oxalic acid and 0.01 molar uranyl sulphate (U02 S04) in water. Under the action of light following reaction take place ... 

Example Radiation of wavelength 250 nm was passed through a cell containing 10 ml of a solution which was 0.05 molar in oxalic acid and 0.01 molar in uranyle sulphate. After absorption of 80 joules of radiation energy, the concentration of oxalic acid was reduced to 0.04 molar. Calculate the quantum yield for the photochemical decomposition of oxalic acid at the given wavelength. 

It is formed in solution by oxidising uranous chloride with nitric acid by dissolving uranic oxide in concentrated hydrochloric acid or by adding barium chloride to a concentrated solution of uranyl sulphate until precipitation is complete. Its aqueous solution on evaporation yields the monohydrate, UOaClj.HaO." The solution is unstable at ordinarj temperatures and slowly deposits uranic hydroxide, which after a time partly redissolves. The uranyl chloride may be reduced in solution to black uranous oxide by the action of magnesium or aluminium powder. The densities of aqueous solutions of uranyl chloride have been determined as follows ... 

Uraayl Chlorate, U02(ClO3)2.xH2O, is obtained by the addition of barium chlorate to a solution of uranyl sulphated After filtration and evaporation, crystals are obtained which are readily soluble in water,... 

Uranyl bromate does not appear to be stable. If a solution of uranyl sulphate is treated with barium bromate, and the filtrate after removal of the precipitate is subjected to evaporation, bromine escapes and a syrupy liquid remains which appears to be a basic bromate. ... 

Uranium Pentoxide, U2O5.—The existence of this oxide is not definitely established. It has been described as the black product obtained when a uranium salt of a volatile acid is strongly ignited in air when uranyl sulphate, (U02)S04.3H20, is rapidly heated when ammonium diuranate, (NH4)2U207-6H20, is heated in a carbon crucible and when a solution of uranyl nitrate is electrolysed. 

Potassium Hexa-uranate, K2U5O49.6H3O, results on strongly heating a nnxture of uranyl sulphate and potassium chloride j by... 

Sodium Triuranate, NagUgO g, is formed by heating together uranyl sulphate and sodium chloride, and washing the residue with water (see potassium hexa-uranate). It yields lustrous, golden-yellow, rhombic crystals, of density 6-9, insoluble in water, but soluble in dilute acids. 

Uranium Oxysulphide, U3O2S4 or UO3.2US2, is formed when uranous oxide, urano-uranic oxide, or ammonium uranate is heated in a stream of hydrogen sulphide or carbon disulphide vapour when one of the oxides is heated with a mixture of ammonium chloride and sulphur or when uranyl sulphate is heated in hydrogen or with potassium pentasulphide. It is a greyish-black powder, which is decomposed by nitric acid %vith deposition of sulphur. 

The hydrates are usually prepared by reduction of uranyl sulphate by means of alcohol and exposure to light, or directly from uranous compounds. 

The nona- or ennea-hydrate, U(S04)a.9H20, is obtained by decomposing a cold solution of uranyl sulphate by means of sodium thio-... 

Uranyl sulphate is readily soluble in water, but accurate solubility determinations have not been made. According to 0. de Coninck, the trihydrate dissolves in about twenty times its weight of water at... 

Freezing-point determinations show that uranyl sulphate dissociates in (Mute solutions to a much less extent than the chloride or nitrate. 

Solutions of uranyl sulphate are fairly stable in diffused daylight, even in presence of alcohol, but readily undergo reduction when j laced in direct sunlight or in ultra- iolet light (see p. 288). 

Basic uranyl sulphates of composition 8U2O3.SO3.2H2O and 4U2O3. SO3.7H2O have been obtained by evaporating at 250 C. solutions of uranyl sulphate containing 3 and 15 per cent, respectively. The former yields citron-yellow, and the latter greyish-yellow, microscopic crystals. 

Ammonio-uranyl Sulphates.—Uranyl sulphate forms yellow addition compounds %vith ammonia, of composition U02S04.a NH3, where (b=2, 3, or 4, the colour of %vhich deepens with increasing ammonia content. ... 

The double salt, 2K2SO4.UO2SO4, is obtained by dissolving uranyl sulphate and excess of potassium sulphate in hot water, and crystallising from the hot solution. At temperatures below 80° C. the salt is decomjDosed by water thus ... 

Uranyl Pyrosulphate, UO2S2O7, may be prepared by adding liquid sulphur trioxide to a solution of anhydrous uranyl sulphate in concentrated sulphuric acid. It separates in small, yellow, fluorescent crystals which are very hygroscopic. 

Uranyl Thiocyanate, U02(CNS)2.8H30, may be obtained by the addition of barium thiocyanate to a solution of uranyl sulphate, and evaporation of the resulting red solution in a vacuum over sulphuric acid. It separates in orange-yellow needles, which are very hygroscopic and readily dissolve in water, alcohol, ether, and acetone ether may be used for extracting it from its aqueous solution. The addition of jyridine to its aqueous solution precipitates a crystalline basic salt of composition 5U02(CNS)2.U03. rH20. 

Uranium is extracted from pitchblende, essentially UgOg. The ore is washed, then fused with sodium carbonate and sodium nitrate. From the mass, dilute sulphuric acid extracts uranyl sulphate, UO2SO4. The addition of ammonium carbonate enables ammonium uranyl carbonate, (NH4)4U02 (003)3, to be crystallised which, on ignition, yields pure U3O3. 

The kerosene was purified by washing with concentrated sulphuric acid (4). The aqueous solutions of uranyl sulphate were prepared by dissolving uranyl sulphate hydrate (UO2SO4 3 0, Yokozawa Chemical Co. Ltd.) in sulphuric acid solutions of the required concentrations. All chemicals were of analytical reagent grade. Extraction and analytical procedures... 

Equal volumes (20 ml) of the TOPO solution in the organic solvent and uranyl sulphate solution containing sulphuric acid were shaken for 10 min in 50 ml stoppered conical flasks in a thermostatic water-bath at the required temperature. Preliminary experiments showed that equilibration is complete in 10 min. The mixture was centrifuged and separated, and uranium was stripped from the organic phase with 0.5 M ammonium carbonate solution, and then the distribution coefficient (the ratio of the equilibrium concentration of uranium in the organic phase to that in the aqueous phase, [U]org/[U]aq) was obtained. 

For the extraction of uranyl sulphate solutions (5 g/1) containing sulphuric acid at various concentrations of TOPO in kerosene at 20 °C, the log-log plots of Eg vs. (C/poPO nCu) at constant sulphuric acid concentrations showed that the Eqn. (2) is... 

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