Rhodium (III) oxide
Crystal structure | ||||||||||||||||
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__ Rh 3+ __ O 2− | ||||||||||||||||
General | ||||||||||||||||
Surname | Rhodium (III) oxide | |||||||||||||||
other names |
Dirhodium trioxide |
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Ratio formula | Rh 2 O 3 | |||||||||||||||
Brief description |
gray-black odorless solid |
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External identifiers / databases | ||||||||||||||||
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properties | ||||||||||||||||
Molar mass | 253.81 g mol −1 | |||||||||||||||
Physical state |
firmly |
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density |
8.20 g cm −3 |
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Melting point |
1100 ° C (decomposition) |
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solubility |
almost insoluble in water |
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safety instructions | ||||||||||||||||
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As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Rhodium (III) oxide is an inorganic chemical compound of rhodium from the group of oxides .
Extraction and presentation
Rhodium (III) oxide can be obtained by reacting anhydrous rhodium (III) salts such as rhodium (III) chloride with oxygen at 750–800 ° C. It can also be obtained directly from the elements. The rhodium (III) oxide hydrate can be obtained by precipitating an aqueous sodium hexachlororhodate or potassium hexachlororhodate solution with sodium or potassium hydroxide solution.
properties
Rhodium (III) oxide is a paramagnetic black-gray odorless solid that is neither soluble in water nor in acids. It has a crystal structure isotypic to that of aluminum (III) oxide (corundum) with the space group R 3 c (space group no. 167) and the lattice parameters a = 547 pm and α = 55 ° 40 '. At 750 ° C this changes into an orthorhombic form. Its pentahydrate (rhodium oxide hydrate) is a pale yellow powder that is insoluble in water and soluble in acids. Reaction with nitric acid leads to rhodium (III) nitrate .
Individual evidence
- ↑ a b c d e f g Data sheet Rhodium (III) oxide, anhydrous, 99.9% (metals basis), Rh 80.6% min from AlfaAesar, accessed on September 1, 2013 ( PDF )(JavaScript required) .
- ^ A b Aaron Wold, Kirby Dwight: Solid State Chemistry: Synthesis, Structure, and Properties of Selected ... Springer, 1993, ISBN 0-412-03621-5 , pp. 119 ( limited preview in Google Book search).
- ↑ a b Georg Brauer (Ed.) U. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume III, Ferdinand Enke, Stuttgart 1981, ISBN 3-432-87823-0 , p. 1634.
- ↑ JMD Coey: The crystal structure of Rh2O3. In: Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. 26, pp. 1876-1877, doi : 10.1107 / S0567740870005022 .