Chromium(III) hydroxide

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]

Chromium(III) hydroxide

Names
IUPAC name Chromium(3+) hydroxide
Identifiers
CAS Number	1308-14-1 Y
3D model (JSmol)	ionic form: Interactive image coordination form: Interactive image
ChemSpider	145861
ECHA InfoCard	100.013.781
PubChem CID	166720
RTECS number	GB2670000
UNII	DX3N9U5Q97 Y
CompTox Dashboard (EPA)	DTXSID0051651
InChI InChI=1S/Cr.3H2O/h;3*1H2 Key: LXMQZGGLHVSEBA-UHFFFAOYSA-N
SMILES ionic form: [OH-].[OH-].[OH-].[Cr+++] coordination form: O[Cr](O)O
Properties
Chemical formula	Cr(OH)3
Molar mass	103.017 g·mol−1
Appearance	green, gelatinous precipitate
Density	3.11 g/cm3
Solubility in water	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

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]