Ammonium diuranate

Crystal structure
__ H +      __ U 6+      __ O 2−      __ N 3−
General
Surname	Ammonium diuranate
Ratio formula	(NH 4 ) 2 U 2 O 7
Brief description	yellow-reddish solid
External identifiers / databases
CAS number 7783-22-4 EC number 231-986-2 ECHA InfoCard 100,029,078 PubChem 197096 Wikidata Q416326
properties
Molar mass	624.13 g mol −1
Physical state	firmly
solubility	almost insoluble in water and alkalis, soluble in acids
Hazard and safety information
Radioactive
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 330-300-373-411 P: ?
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Ammonium diuranate (ADU) is a chemical compound made up of nitrogen , hydrogen , uranium and oxygen . It is created together with sodium diuranate in the production of yellow cake . ADU can be formally characterized by the empirical formula (NH ₄ ) ₂ U ₂ O ₇ . In fact, different species of different composition are found for which the general formula [m UO ₃  · 2n NH ₃  · 2 (m-n) H ₂ O] · p H ₂ O can be formulated.

presentation

Ammonium diuranate is precipitated from uranyl sulfate solution by adding aqueous ammonia solution :

${\displaystyle \mathrm {2\ UO_{2}^{2+}+6\ NH_{3}+3\ H_{2}O\rightarrow } }$ ${\displaystyle \mathrm {(NH_{4})_{2}U_{2}O_{7}+4\ NH_{4}^{+}} }$

This reaction can also be used in analytical chemistry as evidence for uranium (VI) compounds.

use

Ammonium diuranate

The ammonium diuranate obtained through the above reaction (technically also called yellow cake ) is burned to obtain triurano octoxide . This reaction proceeds through several intermediate stages; First, part of the water of crystallization and ammonia are split off before the UO ₃ units are dehydrated and finally oxygen is split off. Formally the overall equation is:

${\displaystyle \mathrm {3\ (NH_{4})_{2}U_{2}O_{7}\rightarrow 2\ U_{3}O_{8}+6\ NH_{3}+3\ H_{2}O+O_{2}} }$

During annealing, uranium (VI) is partially reduced to uranium (IV) in the uranium (IV, VI) oxide.

The triuranium octoxide is reacted with nitric acid in the further process of uranium production . This creates uranyl nitrate , from which pure uranium trioxide can be isolated. This is reduced to uranium dioxide with hydrogen . If uranium dioxide is reacted with hydrofluoric acid and fluorine , uranium hexafluoride is formed , from which pure uranium is finally obtained through reduction using calcium or magnesium .

Individual evidence

1. ↑ ^{a b} SLAC: PHYSICAL CONSTANTS OF INORGANIC COMPOUNDS (PDF; 391 kB).
2. ↑ Entry on uranium compounds in the GESTIS substance database of the IFA , accessed on February 1, 2016 (JavaScript required)
3. ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry uranium compounds with the exception of those specified elsewhere in this Annex in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA) , accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
4. ↑ The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling.
5. ↑ ^{a b} Gmelin's Handbook of Inorganic Chemistry - Uranium, Supplementary Volume Part C 3, Compounds, 8th Edition, Berlin, Heidelberg, 1975.
6. ↑ ^{a b} Nuclear Chemistry - Uranium Production ( English )
7. ^ Harry H. Binder: Lexicon of the chemical elements , S. Hirzel Verlag, Stuttgart 1999, ISBN 3-7776-0736-3 .

literature

• Ingmar Grenthe, Janusz Drożdżynński, Takeo Fujino, Edgar C. Buck, Thomas E. Albrecht-Schmitt, Stephen F. Wolf: Uranium , in: Lester R. Morss, Norman M. Edelstein, Jean Fuger (eds.): The Chemistry of the Actinide and Transactinide Elements , Springer, Dordrecht 2006; ISBN 1-4020-3555-1 , pp. 253-698 ( doi : 10.1007 / 1-4020-3598-5_5 ).