Potassium dichromate

Potassium dichromate
Names
	IUPAC name Potassium dichromate(VI)
	Other names potassium bichromate; bichromate of potash; dipotassium dichromate; dichromic acid, dipotassium salt; chromic acid, dipotassium salt; lópezite;
Identifiers
CAS Number	7778-50-9 ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL1374101;
ChemSpider	22910 ;
ECHA InfoCard	100.029.005
EC Number	231-906-6;
PubChem CID	24502;
RTECS number	HX7680000;
UNII	T4423S18FM ;
UN number	3288
CompTox Dashboard (EPA)	DTXSID5025948 ;
	InChI InChI=1S/2Cr.2K.7O/q;;2+1;;;;;;2-1 Key: KMUONIBRACKNSN-UHFFFAOYSA-N ;
	SMILES [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O;
Properties
Chemical formula	K2Cr2O7
Molar mass	294.185 g/mol
Appearance	red-orange crystalline solid
Odor	odorless
Density	2.676 g/cm3, solid
Melting point	398 °C (748 °F; 671 K)
Boiling point	500 °C (932 °F; 773 K) decomposes
Solubility in water	4.9 g/100 mL (0 °C) ; 13 g/100 mL (20 °C) ; 102 g/100 mL (100 °C)
Solubility	insoluble in alcohol, acetone.
Refractive index (nD)	1.738
Structure
Crystal structure	Triclinic (α-form, <241.6 °C)
Coordination geometry	Tetrahedral (for Cr)
Thermochemistry
Heat capacity (C)	219 J/mol
Std molar; entropy (S⦵298)	291.2 J/(K·mol)
Std enthalpy of; formation (ΔfH⦵298)	−2033 kJ/mol
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	carcinogenic, corrosive
	GHS labelling:
Pictograms
NFPA 704 (fire diamond)	4 0 1 OX
Flash point	Non-flammable
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	25 mg/kg (oral, rat)
Safety data sheet (SDS)	ICSC 1371
Related compounds
Other anions	Potassium chromate; Potassium molybdate; Potassium tungstate
Other cations	Ammonium dichromate; Sodium dichromate
Related compounds	Potassium permanganate
	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

Potassium dichromate, K₂Cr₂O₇, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. As with all hexavalent chromium compounds, it is acutely and chronically harmful to health. It is a crystalline ionic solid with a very bright, red-orange color. The salt is popular in laboratories because it is not deliquescent, in contrast to the more industrially relevant salt sodium dichromate.^[6]

^ "POTASSIUM DICHROMATE LISTING" (PDF). US EPA. 2015-07-23.
^ Binnewies, M.; Milke, E. (2002). Thermochemical Data of Elements and Compounds (2 ed.). Weinheim: Wiley-VCH. p. 405. ISBN 978-3-527-30524-7.
^ Sigma-Aldrich Co., Chromium(VI) oxide. Retrieved on 2014-06-15.
^ Like all compounds of hexavalent chromium, potassium dichromate is carcinogenic
^ Chambers, Michael. "ChemIDplus - 7778-50-9 - KMUONIBRACKNSN-UHFFFAOYSA-N - Potassium dichromate - Similar structures search, synonyms, formulas, resource links, and other chemical information".
^ Gerd Anger, Jost Halstenberg, Klaus Hochgeschwender, Christoph Scherhag, Ulrich Korallus, Herbert Knopf, Peter Schmidt, Manfred Ohlinger, "Chromium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a07_067

[1] "POTASSIUM DICHROMATE LISTING" (PDF). US EPA. 2015-07-23.

[2] Binnewies, M.; Milke, E. (2002). Thermochemical Data of Elements and Compounds (2 ed.). Weinheim: Wiley-VCH. p. 405. ISBN 978-3-527-30524-7.

[sigma-3] Sigma-Aldrich Co., Chromium(VI) oxide. Retrieved on 2014-06-15.

[4] Like all compounds of hexavalent chromium, potassium dichromate is carcinogenic

[5] Chambers, Michael. "ChemIDplus - 7778-50-9 - KMUONIBRACKNSN-UHFFFAOYSA-N - Potassium dichromate - Similar structures search, synonyms, formulas, resource links, and other chemical information".

[Ullmann-6] Gerd Anger, Jost Halstenberg, Klaus Hochgeschwender, Christoph Scherhag, Ulrich Korallus, Herbert Knopf, Peter Schmidt, Manfred Ohlinger, "Chromium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a07_067

[1]

[2]

[4]

[3]

[5]

[6]

Names


IUPAC name Potassium dichromate(VI)
Other names potassium bichromate bichromate of potash dipotassium dichromate dichromic acid, dipotassium salt chromic acid, dipotassium salt lópezite^[1]
Identifiers
CAS Number	7778-50-9^Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL1374101
ChemSpider	22910^Y
ECHA InfoCard	100.029.005
EC Number	231-906-6
PubChem CID	24502
RTECS number	HX7680000
UNII	T4423S18FM^Y
UN number	3288
CompTox Dashboard (EPA)	DTXSID5025948
InChI InChI=1S/2Cr.2K.7O/q;;2+1;;;;;;2-1^Y Key: KMUONIBRACKNSN-UHFFFAOYSA-N^Y
SMILES [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O
Properties
Chemical formula	K₂Cr₂O₇
Molar mass	294.185 g/mol
Appearance	red-orange crystalline solid
Odor	odorless
Density	2.676 g/cm³, solid
Melting point	398 °C (748 °F; 671 K)
Boiling point	500 °C (932 °F; 773 K) decomposes
Solubility in water	4.9 g/100 mL (0 °C) 13 g/100 mL (20 °C) 102 g/100 mL (100 °C)
Solubility	insoluble in alcohol, acetone.
Refractive index (n_D)	1.738
Structure
Crystal structure	Triclinic (α-form, <241.6 °C)
Coordination geometry	Tetrahedral (for Cr)
Thermochemistry
Heat capacity (C)	219 J/mol^[2]
Std molar entropy (S^⦵₂₉₈)	291.2 J/(K·mol)
Std enthalpy of formation (Δ_fH^⦵₂₉₈)	−2033 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	carcinogenic,^[4] corrosive
GHS labelling:
Pictograms	^[3]
NFPA 704 (fire diamond)	4 0 1 OX
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD₅₀ (median dose)	25 mg/kg (oral, rat)^[5]
Safety data sheet (SDS)	ICSC 1371
Related compounds
Other anions	Potassium chromate Potassium molybdate Potassium tungstate
Other cations	Ammonium dichromate Sodium dichromate
Related compounds	Potassium permanganate
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