Uranyl hydroxide

Crystal structure
	__ U 6+ __ O 2−
General
Surname	Uranyl hydroxide
other names	Dihydroxydioxiurane
Ratio formula	UO 2 (OH) 2
External identifiers / databases
PubChem	5465112
ChemSpider	4576989
Wikidata	Q415222
properties
Molar mass	304.04 g mol −1
Physical state	firmly
Hazard and safety information
	; Radioactive
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 .

Uranyl hydroxide is a hydroxide of uranium with the chemical formula UO ₂ (OH) ₂ in the monomeric and (UO ₂ ) ₂ (OH) ₄ in the dimeric form. Both isomers can exist in normal aqueous medium. Uranyl hydroxide hydrate is precipitated as a gelatinous yellow cake from oxidized uranium lye at approximately neutral pH .

properties

Uranyl hydroxide is derived as the uranates from the hypothetical uranium acid from which can react as well as the acid, both as the base. The uranyl compounds are formed as the base and the uraniumates as the acid . The latter, however, are not stable and convert into the di-uranates (U ₂ O ₇²⁻ ). The corresponding reaction equations are as follows:

{\ displaystyle \ mathrm {UO_ {4} ^ {\, 2 -} + 2 \ H ^ {\, +} \ rightleftharpoons \ UO_ {2} (OH) _ {2} \ rightleftharpoons \ UO_ {2} ^ { \, 2 +} + 2 \ OH ^ {\, -}}}

Due to these reactions, uranyl salts and uranyl salts can easily be converted into the other form.

Modifications

The modifications were described with the following properties:

modification	colour	Space group	Crystal system	Lattice constants					Density / g cm ⁻³
modification	colour	Space group	Crystal system	a / Å	b / Å	c / Å	β / °	Z	Density / g cm ⁻³
α ‐ UO ₂ (OH) ₂	greenish yellow	Cmce (No. 64)Template: room group / 64	Orthorhombic	4,242	10.302	6.868		4th	6.73
β ‐ UO ₂ (OH) ₂	yellow-green	Pbca (No. 61)Template: room group / 61	Orthorhombic	5.6438	6.2867	9.9372		4th	5.73
γ ‐ UO ₂ (OH) ₂	gray chamois	P 2 ₁ / c (No. 14)Template: room group / 14	Monoclinic	6.419	5.518	5.561	112.77	2	5.56
UO ₂ (OH) ₂ · H ₂ O	light yellow	Pbna (No. 60, position 5)Template: room group / 60.5	Orthorhombic	13.977	16,696	14.672		32	5

use

Uranyl hydroxide used to be used in glass and ceramic production to color the glass phases and to produce pigments for high temperature firing. Introducing alkaline diuranates into glass creates a yellow tone in the glass and a green reflection. In addition, this glass emits cold light under ultraviolet light and fluoresces . The uranyl hydroxide conducts protons when it is steadily compressed and then slowly relaxed again; and it is used as a component in fuel cells .

Health effects

Uranyl hydroxide damages the genetic material , leads to malformations and is radioactive ; therefore, it should be handled with extreme caution.

Individual evidence

↑ Entry on uranium compounds in the GESTIS substance database of the IFA , accessed on February 1, 2016 (JavaScript required)

↑ 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 .

↑ The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling.

^ AF Holleman , E. Wiberg : Textbook of Inorganic Chemistry . 37-39 Edition. Walter de Gruyter, Berlin 1956, p. 519.

↑ 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 .

↑ The former name of this group of rooms was Ccma .

↑ United States Patent 4179491: Electrical device with separator as conductor for hydrogen cations .

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 .
CA Alexander: "Volatilization of urania under strongly oxidizing conditions", in: Journal of Nuclear Materials , 2005 , 346 , pp. 312-318; doi : 10.1016 / j.jnucmat.2005.07.013 .

[GESTIS-1] Entry on uranium compounds in the GESTIS substance database of the IFA , accessed on February 1, 2016 (JavaScript required)

[CLP_100.240.790-2] 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 .

[3] The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling.

[4] AF Holleman , E. Wiberg : Textbook of Inorganic Chemistry . 37-39 Edition. Walter de Gruyter, Berlin 1956, p. 519.

[5] 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 .