Potassium dichromate

Not to be confused with Potassium chromate.
Potassium dichromate
Potassium dichromate
Unit cell of 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[1]
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.029.005 Edit this at Wikidata
EC Number
  • 231-906-6
RTECS number
  • HX7680000
UNII
UN number 3288
  • InChI=1S/2Cr.2K.7O/q;;2*+1;;;;;;2*-1 checkY
    Key: KMUONIBRACKNSN-UHFFFAOYSA-N checkY
  • [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O
Properties
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
4.9 g/100 mL (0 °C)
13 g/100 mL (20 °C)
102 g/100 mL (100 °C)
Solubility insoluble in alcohol, acetone.
1.738
Structure
Triclinic (α-form, <241.6 °C)
Tetrahedral (for Cr)
Thermochemistry
219 J/mol[2]
291.2 J/(K·mol)
−2033 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 carcinogenic,[4] corrosive
GHS labelling:
GHS03: OxidizingGHS05: CorrosiveGHS06: ToxicGHS08: Health hazardGHS09: Environmental hazard[3]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
4
0
1
OX
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
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).
checkY verify (what is checkY☒N ?)

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]

  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.
  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".
  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