Uranyl nitrate crystals

There have been many instances of examination of the effect of additive product on the initiation of nucleation and growth processes. In early work on the dehydration of crystalline hydrates, reaction was initiated on all surfaces by rubbing with the anhydrous material [400]. An interesting application of the opposite effect was used by Franklin and Flanagan [62] to inhibit reaction at selected crystal faces of uranyl nitrate hexa-hydrate by coating with an impermeable material. In other reactions, the product does not so readily interact with reactant surfaces, e.g. nickel metal (having oxidized boundaries) does not detectably catalyze the decomposition of nickel formate [222],... 

Uranyl hydroxides, 25 430 Uranyl metaphosphates, 25 433 Uranyl nitrate, 25 428 Uranyl perchlorate crystals, 25 429 Uranyl sulfate system, 25 429 Urban air quality, 17 814—815 Urea(s), 8 206-207... 

As has been discussed, ordinary formamides have a barrier of about 21 kcal/ mol, which is a little less than that required for the isolation of atropisomers at room temperature. This means that, at a temperature slightly lower than ambient, it may be possible to obtain stable rotamers. This possibility was first realized by Gutowsky, Jonas, and Siddall (40). They used a uranyl nitrate complex of N-benzyl-N-methylformamide (4) crystallized from dichloromethane. When the crystals were washed with ice water to strip off the uranyl nitrate, a mixture of E and Z forms (Z/E = 1.6) was obtained. Since the equilibrium mixture gives a Z/E value of 0.8, it was possible to perform a kinetic study of equilibration... 

The purification of uranium by fractional crystallization involves repeated recrystallizations of U02(N03)2 from water or nitric acid, three usually being sufficient. The composition of the crystalline product may range from U02(N03)v2H20 to U02(N03)2 6H20 depending upon the temperature, acidity and uranyl nitrate concentration of the solution.198... 

ASTM C788-98 Standard specification for nuclear-grade uranyl nitrate solution or crystals. 

Stoichiometrical quantities of the HDBM (l,3-diphenyl-l,3-pentanedione) and U02 (CH3COO)2 were dissolved in tepid ethanol. The solution was concentrated and left at room temperature until crystallization. The product was washed with ether and dried at 130°C and a pressure of I0 7 mm Hg in an Abderhalden drying apparatus provided with P4O]0. Uranyl bis-(2-hydroxybenzaldehyde) [79] was synthesized from stoichiometric quantities of an alcoholic solution of 2-hydroxybenzaldehyde and an aqueous solution of uranyl nitrate trihydrate, U02(N03)2 3H20. It is noted [79] that, for uranyl P-diketonates his-(2-hydroxybenzaldehyde) and b is-(2 - h ydroxy-1 -naphtli a I d e h y de), their crystals do not exhibit the appropriate size and crystalline shape to perform polarization measurement in the solid state. 

Uranyl Nitrate. The presence of ether in the crystals may result in explosions when the crystals are disturbed. Solutions of the salt in ether should not be exposed to sunlight to avoid the possibility of explosions.17 18... 

The uranyl nitrate is extracted back into the aqueous phase and crystallized as the... 

If the potassium salt is dissolved in water containing not more than 13 per cent, of the acid fluoride of potassium, the solution on concentration yields triclinic crystals of the compound 2UO2F2.5KF. If excess of uranyl nitrate is present in the solution, raonoclinic crystals of the compound 2UO2F2.3KF are obtained. 

A saturated solution of uranyl chloride in hydrochloric acid when cooled to —10° C. yields yellow crystals of an unstable hydrochloride, U02Cl2.HC1.2H20. The compound may also be obtained by the action of hydrochloric acid on uranyl nitrate. ... 

Uranyl Iodide, UOglj, is prepared by adding barium iodide in slight excess to an ethereal solution of uranyl nitrate. It separates in red crystals which are deliquescent and unstable, losing iodine in the air, and in aqueous solution forming hydriodic acid and free iodine. ... 

Lithium Peruranate, Li303.(U04)2.8Hj0, is obtained by treating a solution of uranyl nitrate with lithium hydroxide and hydrogen peroxide, and then precipitating with alcohol. It yields minute, pale yellow crystals. An unstable compound, (Li202)2U0, has also been obtained. 

The crystals of uranyl nitrate hexahydrate, which have density 2-807 and are diamagnetic, deliquesce in moist air. At 15° C. the vapour 2Dressureispracticallj- negligible. The melting-point is 60-2° C., and the liquid boils at 118° C. ... 

A crystal structure of a U02 /N03/malonamide complex has been reported by Lumetta et al. Uranyl nitrate has been crystallized with N,N,N, N -tetramethylmalonamide (TMMA)... 

U is then heated to 50-65 C, which assists the back extraction, and contacted with demineralized water to give a pure aqueous uranyl nitrate product stream and a barren solvent phase for recycle. The product solution might contain ca. 100 g dm while the aqueous raffinate from the first extraction may contain ca. 0.1 g dm The concentrations of boron and cadmium in the solid U02(N03)2 6H20 product obtained by evaporation of and crystallization from the product solution will be 0.2 p.p.m. or less. 

Uranyl sulfate, UO2SO4 3 H20, is prepared by the crystallization of a solution of uranyl hydroxide in dilute sulfuric acid or by heating uranyl nitrate with sulfuric acid. It forms yellow-green crystals, which under the microscope show a beautiful fluorescence. On exposure to air they loose water slowly, and at 115° a monohydrate is formed while at 175° the anhydrous salt is produced. Both acid salts and double alkali sulfates are formed. 

Uranyl nitrate, U02(N0>)2 - 6 H20 is commonly called uranium nitrate and is the best known and most widely used uranyl salt. It may be prepared by dissolving any oxide of uranium in nitric acid. It forms lemon-yellow prisms which have a green fluorescence. They are readily soluble in water and are deliquescent. When shaken, rubbed, or crushed, the crystals show remarkable triboluminescence, with occasionally somewhat violent detonations. Numerous theories have been advanced to account... 

Two hundred fifty milliliters of 1.1 M orthophosphoric acid is added with vigorous stirring to 250 ml. of 1 M uranyl nitrate or perchlorate solution. The solution is seeded with a few crystals of the product to promote immediate precipitation. The suspension is then stirred for 12 hours and the mother liquor removed by centrifuging or filtering. The precipitate is slurried in 250 ml. of ca. 0.01 M perchloric acid for 12 hours, and the suspension is filtered. The solid is then slurried twice in 125-ml. portions of acetone to remove solution and sorbed perchlorate and separated from each wash solution by filtration. The sample is dried in a vacuum desiccator, using continuous... 

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