Chromium(III) hydroxide is a gelatinous green inorganic compound with the chemical formula . It is a polymer with an undefined structure and low solubility. It is amphoteric, dissolving in both strong alkalis and strong acids.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.
Preparation Chromium(III) hydroxide is prepared by treating an aqueous solution of hydrated chromium trichloride with ammonia.
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: The following idealized equation suffices:
Use It is used as a pigment, as a mordant, and as a catalyst for organic reactions.
Natural occurrence Three chromium(III) oxide hydroxide (CrO(OH)) minerals are known: bracewellite, grimaldiite and guyanaite.
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