Gold (III) oxide
Crystal structure | |||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
__ Au 3+ __ O 2− | |||||||||||||||||||
General | |||||||||||||||||||
Surname | Gold (III) oxide | ||||||||||||||||||
Ratio formula | Au 2 O 3 | ||||||||||||||||||
Brief description |
brown powder |
||||||||||||||||||
External identifiers / databases | |||||||||||||||||||
|
|||||||||||||||||||
properties | |||||||||||||||||||
Molar mass | 441.93 g · mol -1 | ||||||||||||||||||
Physical state |
firmly |
||||||||||||||||||
density |
3.6 g cm −3 |
||||||||||||||||||
Melting point |
Decomposes at approx. 150 ° C into Au and O 2 |
||||||||||||||||||
solubility |
almost insoluble in water |
||||||||||||||||||
safety instructions | |||||||||||||||||||
|
|||||||||||||||||||
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Gold (III) oxide (Au 2 O 3 ) is the most stable known oxide of the chemical element gold . It is a red-brown, crystalline, light-sensitive solid. The compound is thermally unstable and decomposes back into the elements above about 160 ° C. Au 2 O 3 has a distorted square-planar crystal structure consisting of AuO 4 units.
presentation
Due to the noble character of elemental gold, the connection cannot be established by oxidizing it with oxygen . However, it can be represented by the direct reaction of gold with an oxygen plasma . Chemically, one starts from trichlorogold hydrate AuCl 3 · H 2 O (actually hydrogen trichlorohydroxidoaurate (III) H [AuCl 3 (OH)]) or tetrachloridogauric acid H [AuCl 4 ] · 4 H 2 O, which is stable in aqueous solution Sodium carbonate is added when a brown precipitate Au 2 O 3 · x H 2 O separates out. After drying over silica gel, this water splits off and results in Au 2 O 3 · 2-3 H 2 O. This can then be purified further by tempering for four weeks in water at 280 ° C and 3000 bar pressure (see principle of the smallest compulsion ) polycrystalline and anhydrous gold (III) oxide Au 2 O 3 .
use
Gold oxide can be used to color glasses ( gold ruby glass ), special applications in optoelectronics are also possible.
Individual evidence
- ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 .
- ↑ a b c data sheet gold (III) oxide from AlfaAesar, accessed on February 2, 2010 ( PDF )(JavaScript required) . .
- ↑ a b Data sheet Gold (III) oxide hydrate from Sigma-Aldrich , accessed on April 3, 2011 ( PDF ).
- ↑ Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 1090.
Web links
- Jörg Michael Gottfried: CO oxidation on gold, adsorption and reaction of oxygen, carbon monoxide and carbon dioxide on an Au (110) - (1x2) surface , dissertation at the FU Berlin
- 3D images with the help of gold oxide