Dichromic acid

Structural formula
General
Surname	Dichromic acid
Molecular formula	H 2 Cr 2 O 7
External identifiers / databases
EC number	236-881-5
ECHA InfoCard	100.033.513
PubChem	26090
Wikidata	Q905857
properties
Molar mass	218.00 g mol −1
safety instructions
GHS hazard labeling ; no classification available
GHS hazard labeling ; no classification available
Authorization procedure under REACH	of particular concern : carcinogenic ( CMR ); subject to approval
MAK	Switzerland: 5 μg m −3 (calculated as chromium)
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Dichromic acid is a strong biprotonic acid with the empirical formula H ₂ Cr ₂ O ₇ . It is more acidic than chromic acid . The p K _s1 value is in the negative range, the p K _s2 value (HCr ₂ O ₇^- ) is 0.07. Like chromic acid, it only exists in a dilute solution and is unknown in its pure form.

Dichromic acid is the acid on which dichromates (e.g. potassium dichromate ) are based and, like them, has a strong oxidation potential .

Both substances are mostly avoided because of the toxicity of the chromium (VI) anions they contain , but in some attempts they cannot be avoided or replaced. Use, especially by laypeople, is not recommended.

Individual evidence

↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
↑ 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): Limit values - current MAK and BAT values (search for 13530-68-2 or dichromic acid ), accessed on October 27, 2015.
^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 1568.

[NV-1] This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.

[SVHC-2] Entry in the SVHC list of the European Chemicals Agency , accessed on July 16, 2014.

[Zulassungspflicht-3] Entry in the register of substances subject to authorization of the European Chemicals Agency , accessed on July 16, 2014.

[4] Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 13530-68-2 or dichromic acid ), accessed on October 27, 2015.

[HoWi2007-5] AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 1568.