Chromium trioxide
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2008-06-19T17:20:13Z
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{{Chembox new
| ImageFile =Chrom(VI)-oxid.jpg
| ImageSize =
| IUPACName = Chromium(VI) oxide
| OtherNames = Chromium trioxide
| Section1 = {{Chembox Identifiers
| CASNo = 1333-82-0
| PubChem =
| SMILES = O=Cr(=O)(O)
| RTECS = GB6650000
}}
| Section2 = {{Chembox Properties
| Formula = CrO<sub>3</sub>
| MolarMass = 99.994 g/mol
| Appearance = Dark red solid
| Density = 2.70 g/cm<sup>3</sup>, solid
| MeltingPt = 197 °C
| BoilingPt = 250 °C, decomposes
| Solubility = 63 g/100 mL
}}
| Section3 = {{Chembox Hazards
| EUClass = Oxidizer ('''O'''), very toxic ('''T+'''), dangerous for the environment ('''N''')
| FlashPt =
| Autoignition =
| RPhrases = {{R45}} {{R46}} {{R9}} {{R24/25}} {{R26}} {{R35}} {{R42/43}} {{R48/23}} {{R62}} {{R50/53}}
| SPhrases = {{S53}} {{S45}} {{S60}} {{S61}}
| NFPA-H = 3
| NFPA-F = 0
| NFPA-R = 1
| NFPA-O = OX
}}
}}
The acid [[anhydride]] of [[chromic acid]] is '''chromium trioxide''' or '''chromium(VI) oxide'''; industrially, this compound is sometimes sold as "[[chromic acid]]".<ref name = chemicalland21>{{cite web | url = http://www.chemicalland21.com/industrialchem/inorganic/CHROMIUM%20TRIOXIDE.htm | title = Chromium Trioxide | publisher = Chemicalland21}}</ref>
This compound is an intensely-colored dark red/orange brown, water-soluble, granular [[solid]] which is stable by itself, but is a strong [[oxidant]] which will [[chemical reaction|react]] when mixed with many things that can be oxidized. Ethanol, for example, will ignite on contact with it.
==Production==
Chromium trioxide is produced commercially by the reaction of [[sodium dichromate]] with concentrated [[sulfuric acid]].<ref name = chemicalland21/>
==Structure and chemistry==
Chromium trioxide consists of chains of tetrahedrally coordinated chromium atoms that share vertices. Each [[chromium]] atom therefore has "half share of two oxygen atoms" and two oxygen atoms that are not shared, giving an overall stoichiometry of 1:3.<ref name = cotton>{{Cotton&Wilkinson6th}}</ref><br />
Chromium trioxide decomposes above 197°C liberating oxygen eventually giving [[chromium(III) oxide|Cr<sub>2</sub>O<sub>3</sub>]]. The reaction of chromium trioxide with organic substances is potentially explosive. In spite of this, CrO<sub>3</sub> is used in organic chemistry as an oxidant, often dissolved in [[acetic acid]],<ref name = cotton /> or [[acetone]] in the case of the [[Jones oxidation]].
==Safety==
Chromium trioxide is highly toxic, corrosive, and carcinogenic.<ref>{{cite web | url = http://www.jtbaker.com/msds/englishhtml/C4400.htm | publisher = J. T. Baker | title = Chromium Trioxide (MSDS) | accessdate = 2007-09-13}}</ref>
Chorium trioxide may cause cancer and/or heritable genetic damage. It is explosive when mixed with combustible material. It is toxic in contact with skin and if swallowed and very toxic by inhalation. CrO<sub>3</sub> causes severe burns and may cause sensitisation by inhalation and skin contact. It is also toxic: danger of serious damage to health by prolonged exposure through inhalation. There is a possible risk of impaired fertility. CrO<sub>3</sub> is very toxic to aquatic organisms may cause long-term adverse effects in the aquatic environment.
==References==
<references />
[[Category:Oxides]] [[Category:Chromium compounds]]
[[ar:أكسيد كروم سداسي]]
[[de:Chrom(VI)-oxid]]
[[fr:Trioxyde de chrome]]
[[it:Anidride cromica]]
[[nl:Chroomtrioxide]]
[[pt:Trióxido de cromo]]
[[ru:Оксид хрома(VI)]]
[[zh:三氧化铬]]