Chromium(III) hydroxide

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Chromium(III) hydroxide
Chromium(III) hydroxide.svg
Chromium(III) hydroxide.jpg
Names
IUPAC name
Chromium(3+) hydroxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.013.781 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
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
Appearancegreen, 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).

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.[ citation needed ]

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. 1 2 3 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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