Chromium(III) hydroxide

Chromium(III) hydroxide
Names
IUPAC name
Chromium(3+) hydroxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.013.781
RTECS number
  • GB2670000
UNII
  • InChI=1S/Cr.3H2O/h;3*1H2
    Key: LXMQZGGLHVSEBA-UHFFFAOYSA-N
  • ionic form: [OH-].[OH-].[OH-].[Cr+++]
  • coordination form: O[Cr](O)O
Properties
Cr(OH)3
Molar mass 103.017 g·mol−1
Appearance green, gelatinous precipitate
Density 3.11 g/cm3
insoluble
Hazards
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1 mg/m3[1]
REL (Recommended)
 TWA 0.5 mg/m3[1]
IDLH (Immediate danger)
 250 mg/m3[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Chromium(III) hydroxide is a gelatinous green inorganic compound with the chemical formula Cr(OH)3. It is a polymer with an undefined structure and low solubility. It is amphoteric, dissolving in both strong alkalis and strong acids.[2]

In alkali: Cr(OH)3 + OH− → CrO−2 + 2 H2O
In acid: Cr(OH)3(OH2)3 + 3 H+ → [Cr(OH2)6]3+

It is used as a pigment, as a mordant, and as a catalyst for organic reactions.[3]

It is manufactured by adding a solution of ammonium hydroxide to a solution of chromium salt.

Pure Cr(OH)3 is as yet (2020) unknown among the mineral species. However, three natural polymorphs of the chromium(III) oxide hydroxide, CrO(OH), are known: bracewellite, grimaldiite and guyanaite.[4][5][6][7]

References

  1. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0141". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ Rai, Dhanpat; Sass, Bruce M.; Moore, Dean A. "Chromium(III) hydrolysis constants and solubility of chromium(III) hydroxide" Inorganic Chemistry 1987, volume 26, pp. 345-9. doi:10.1021/ic00250a002
  3. ^ Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Chromium". Lehrbuch der Anorganischen Chemie (in German) (91–100 ed.). Walter de Gruyter. pp. 1081–1095. ISBN 3-11-007511-3.
  4. ^ "Bracewellite".
  5. ^ "Grimaldiite".
  6. ^ "Guyanaite".
  7. ^ "List of Minerals". 21 March 2011.
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