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]

Contents

Preparation

Chromium(III) hydroxide is prepared by treating an aqueous solution of hydrated chromium trichloride with ammonia. [3]

It can also be prepared by treating an aqueous solution of chromium(III) nitrate with potassium hydroxide until the pH is within 7 to 8: [4] The following idealize equation suffices:

Cr(NO3)3 + 3 KOH → Cr(OH)3 + 3 KNO3

Use

It is used as a pigment, as a mordant, and as a catalyst for organic reactions. [5]

Natural occurrence

Three chromium(III) oxide hydroxide (CrO(OH)) minerals are known: bracewellite, grimaldiite and guyanaite. [6] [7] [8] [9]

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. ↑ F. Hein and S. Herzog (1963). "Chromium, Molybdenum, Tungsten, Uranium". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2. NY, NY: Academic Press. p. 1345.
  4. ↑ Papassiopi, N.; Vaxevanidou, K.; Christou, C.; Karagianni, E.; Antipas, G. S. E. (2014-01-15). "Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides". Journal of Hazardous Materials. 264: 490–497. doi:10.1016/j.jhazmat.2013.09.058. ISSN   0304-3894.
  5. ↑ 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.
  6. ↑ "Bracewellite".
  7. ↑ "Grimaldiite".
  8. ↑ "Guyanaite".
  9. ↑ "List of Minerals". 21 March 2011.
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