Chromium (VI) oxide
|__ Cr 6+ __ O 2−|
|Surname||Chromium (VI) oxide|
|Ratio formula||CrO 3|
dark red, odorless crystal needles
|External identifiers / databases|
|Molar mass||99.99 g · mol -1|
2.7 g cm −3 (20 ° C)
197 ° C
Decomposition above 200 ° C
very good in water (1854 g l −1 at 20 ° C)
|Authorization procedure under REACH|
|As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .|
Chromium (VI) oxide , also known as chromium trioxide (CrO 3 ), is an oxide of chromium . It is a dark red solid that is hygroscopic and easily soluble in water . The aqueous solution is strongly acidic ( chromic acid ). The substance poses a number of dangers.
Chromium (VI) oxide forms red-violet, odorless, needle-shaped crystals. It dissolves in a lot of water to form yellow chromic acid (H 2 CrO 4 ). Condensed chromic acids are also formed in a little water. When chromium (VI) oxide is glowing, it decomposes and forms chromium (III) oxide and oxygen :
The crystal structure of chromium (VI) oxide consists of chains of corner-linked tetrahedra that are clearly distorted in the direction of the chain.
Synthesis / representation
Chromium (VI) oxide is produced by precipitation from a concentrated chromate solution with concentrated sulfuric acid.
Chromium VI is or has been used in the case of unprofessional tanning .
Chromium (VI) oxide is fire-promoting and increases the risk of fire if it comes into contact with flammable substances. Mixing with flammable substances poses a risk of explosion. Chromium (VI) oxide is very toxic and is both mutagenic and carcinogenic . As little as 0.6 g taken orally can be fatal. If swallowed, digestive disorders, kidney damage, cramps and paralysis are the result. Aqueous solutions of chromium (VI) oxide are highly corrosive. The solid also leads to severe burns on contact with skin and mucous membranes . Chromium (VI) oxide is dangerous for the environment and extremely hazardous to water ( water hazard class 3).
- Entry on Chromium trioxide 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 .
- Entry in the SVHC list of the European Chemicals Agency , accessed on July 16, 2014.
- Entry in the register of substances subject to authorization of the European Chemicals Agency , accessed on July 16, 2014.
- Swiss Accident Insurance Fund (Suva): Limits - Current MAK and BAT values (search for 1333-82-0 or chromium (VI) oxide ), accessed on October 27, 2015.
- Data sheet chromium (VI) oxide (PDF) from Merck , accessed on January 19, 2011.
- JS Stephens, DWJ Cruickshank: The Crystal Structure of (CrO 3 ) ∞ in: Acta Cryst. , 1970 , B26 , pp. 222-226; doi : 10.1107 / S0567740870002182
- animal transport. Retrieved February 21, 2020 .