Chemistry:Chromium(III) hydroxide
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Short description: Chemical compound (Cr(OH)3)
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| IUPAC name
Chromium(3+) hydroxide
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| Properties | |
| Cr(OH) 3 | |
| Molar mass | 103.02 g/mol |
| Appearance | green, gelatinous precipitate |
| Density | 3.11 g/cm3 |
| insoluble | |
| Hazards | |
| NIOSH (US health exposure limits): | |
PEL (Permissible)
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TWA 1 mg/m3[1] |
REL (Recommended)
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TWA 0.5 mg/m3[1] |
IDLH (Immediate danger)
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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 | |
Tracking categories (test):
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: [math]\ce{ Cr(OH)3 + OH- -> CrO2- + 2 H2O }[/math]
- In acid: [math]\ce{ Cr(OH)3(OH2)3 + 3 H+ -> Cr(OH2)6^3+ }[/math]
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 oxyhydroxide, CrO(OH), are known: bracewellite, grimaldiite and guyanaite.[4][5][6][7]
References
- ↑ 1.0 1.1 1.2 NIOSH Pocket Guide to Chemical Hazards. "#0141". National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/npg/npgd0141.html.
- ↑ 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
- ↑ Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Chromium" (in German). Lehrbuch der Anorganischen Chemie (91–100 ed.). Walter de Gruyter. pp. 1081–1095. ISBN 3-11-007511-3.
- ↑ "Bracewellite". https://www.mindat.org/min-748.html.
- ↑ "Grimaldiite". https://www.mindat.org/min-1750.html.
- ↑ "Guyanaite". https://www.mindat.org/min-1783.html.
- ↑ "List of Minerals". 21 March 2011. https://www.ima-mineralogy.org/Minlist.htm.
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