Chromic acid

Chromic acid
Dichromic acid
	; Dichromic acid (left) and chromic acid (right)
Names
	IUPAC names Chromic acid; Dichromic acid
	Systematic IUPAC name Dihydroxidodioxidochromium
	Other names Chromic(VI) acid; Tetraoxochromic acid
Identifiers
CAS Number	7738-94-5 ;
3D model (JSmol)	Interactive image; Interactive image;
ChEBI	CHEBI:33143 ;
ChemSpider	22834 ;
ECHA InfoCard	100.028.910
EC Number	231-801-5;
Gmelin Reference	25982
PubChem CID	24425;
UNII	SA8VOV0V7Q ;
UN number	1755 1463
CompTox Dashboard (EPA)	DTXSID8034455 ;
	InChI InChI=1S/Cr.2H2O.2O/h;21H2;;/q+2;;;;/p-2 Key: KRVSOGSZCMJSLX-UHFFFAOYSA-L ; InChI=1/Cr.2H2O.2O/h;21H2;;/q+2;;;;/p-2/rCrH2O4/c2-1(3,4)5/h2-3H Key: KRVSOGSZCMJSLX-OOUCQFSRAZ;
	SMILES O[Cr](O)(=O)=O; O=[Cr](=O)(O)O;
Properties
Chemical formula	H2CrO4 (chromic acid); H2Cr2O7 (dichromic acid)
Molar mass	118.008 g/mol (chromic acid); 218.001 g/mol (dichromic acid)
Appearance	Dark purplish-red sand-like crystalline solid or powder
Odor	Odorless
Density	1.201 g/cm3
Melting point	197 °C (387 °F; 470 K)
Boiling point	250 °C (482 °F; 523 K) (decomposes)
Solubility in water	169 g/(100 mL)
Acidity (pKa)	−0.8 to 1.6 (chromic acid)
Conjugate base	Chromate and dichromate
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	highly toxic, carcinogen, corrosive
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H271, H300+H310+H330, H301, H314, H317, H334, H340, H341, H350, H361, H372, H410
Precautionary statements	P201, P202, P210, P220, P221, P260, P261, P262, P264, P270, P271, P272, P273, P280, P281, P283, P284, P285, P301+P310, P301+P330+P331, P302+P350, P302+P352, P303+P361+P353, P304+P340, P304+P341, P305+P351+P338, P306+P360, P308+P313, P310, P314, P320, P321, P322, P330, P333+P313, P342+P311, P361, P363, P370+P378, P371+P380+P375, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)	4 0 1 COR
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	51.9 mg/kg (H2CrO4·2Na, rat, oral)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.005 mg/m3
REL (Recommended)	TWA 0.001 mg Cr(VI)/m3
IDLH (Immediate danger)	15 mg Cr(VI)/m3
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Chromic acid is jargon for a solution formed by the addition of sulfuric acid to aqueous solutions of dichromate. It consists at least in part of chromium trioxide.

The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixture for glass. Chromic acid may also refer to the molecular species, H₂CrO₄ of which the trioxide is the anhydride. Chromic acid features chromium in an oxidation state of +6 (and a valence of VI or 6). It is a strong and corrosive oxidising agent and a moderate carcinogen.

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