Chromium(III) hydroxide
| Names | |
|---|---|
| IUPAC name
Chromium(3+) hydroxide | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.013.781 |
PubChem CID |
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| RTECS number |
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| UNII | |
CompTox Dashboard (EPA) |
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| 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 |
REL (Recommended) |
TWA 0.5 mg/m3 |
IDLH (Immediate danger) |
250 mg/m3 |
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.
- 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.
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.