Chromite (compound)

This article is about the chromium(III) anion and its salts. For the mineral, see chromite. For the chromium(VI) anion and its salts, see chromate.

In chemistry, a chromite refers to an anionic complex of chromium(III) or a salt containing such an anion, especially the anions [Cr(OH)₆]³⁻ and CrO−
2.^[1][2][3] Under IUPAC naming conventions, chromite is referred to as chromate(III). Other derived anions are also regarded as chromites, such as hexacyanochromite ([Cr(CN)₆]³⁻).^[1] Chromite salts such as sodium chromite may be regarded as salts of chromous acid, HCrO₂.^[4][5] They are formed by reaction of chromium(III) oxide with concentrated alkali, such as sodium hydroxide:^[6]

Cr₂O₃ + 3 H₂O + 6 NaOH 2 Na₃[Cr(OH)₆]

The equilibrium is driven to the right in strongly basic conditions and to the left in neutral conditions.

Chromites decompose in acids and hydrolyze in neutral conditions, forming the hydroxide and the chromium(III) oxide.^[2]

References

1. ^ ^{a b} Mary Eagleson, ed (1994). "Chromates". Concise encyclopedia chemistry. Walter de Gruyter. p. 220. ISBN 3110114518. 
2. ^ ^{a b} Hamilton Perkins Cady (2009). General Chemistry. BiblioBazaar, LLC. p. 446. ISBN 1113733985. 
3. ^ H. Wayne Richardson (1997). Handbook of copper compounds and applications. CRC Press. p. 82. ISBN 0824789989. 
4. ^ Meisenheimer, R.; Swalen, J. (1961). "Magnetic Properties of HCrO₂ and DCrO₂". Physical Review 123 (3): 831–834. Bibcode 1961PhRv..123..831M. doi:10.1103/PhysRev.123.831.  edit
5. ^ Hamilton, W. C.; Ibers, J. A. (1963). "Structures of HCrO₂ and DCrO₂". Acta Crystallographica 16: 1209–1212. doi:10.1107/S0365110X63003182.  edit
6. ^ Kenneth Malcolm Mackay; Rosemary Ann Mackay; W. Henderson (2002). Introduction to modern inorganic chemistry (6th ed.). CRC Press. p. 327. ISBN 0748764208.