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 Y
3D model (JSmol)	Interactive image Interactive image
ChEBI	CHEBI:33143 Y
ChemSpider	22834 Y
ECHA InfoCard	100.028.910
EC Number	231-801-5
Gmelin Reference	25982
PubChem CID	24425
UNII	SA8VOV0V7Q Y
UN number	1755 1463
CompTox Dashboard (EPA)	DTXSID8034455
InChI InChI=1S/Cr.2H2O.2O/h;2*1H2;;/q+2;;;;/p-2 Y Key: KRVSOGSZCMJSLX-UHFFFAOYSA-L Y InChI=1/Cr.2H2O.2O/h;2*1H2;;/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[clarification needed]
Odor	Odorless
Density	1.201 g/cm3[clarification needed]
Melting point	197 °C (387 °F; 470 K) [clarification needed]
Boiling point	250 °C (482 °F; 523 K) (decomposes)[clarification needed]
Solubility in water	169 g/(100 mL)[clarification needed]
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)[2]
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.005 mg/m3[1]
REL (Recommended)	TWA 0.001 mg Cr(VI)/m3[1]
IDLH (Immediate danger)	15 mg Cr(VI)/m3[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) 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.^[3]

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 oxidizing agent and a moderate carcinogen.