CoCrO4

CoCrO4, cobalt(II) chromate, is an inorganic salt with the formula CoCrO4. It consists of cobalt in the +2 oxidation state and the chromate anion CrO4^2−. In solid form it is typically a yellow to orange insoluble compound. It is sparingly soluble in water and readily forms a precipitate when solutions containing Co2+ ions are treated with chromate ions.

Preparation and occurrence: CoCrO4 can be prepared by mixing aqueous solutions of cobalt(II) salts (for example cobalt(II) sulfate or cobalt(II) nitrate) with a soluble chromate source such as potassium chromate, yielding CoCrO4 as a precipitate. It is an example of a transition metal chromate and is usually encountered as a crystalline solid.

Properties and behavior: The compound is an inorganic oxide salt that is insoluble in water. It is relatively stable at ambient temperatures; upon heating, CoCrO4 decomposes to cobalt and chromium oxides, releasing oxygen.

Applications and safety: CoCrO4 has been investigated as a pigment for ceramics and glass, contributing yellow to orange hues. However, its use has been limited due to the toxicity associated with hexavalent chromium compounds and the general hazards of cobalt salts. Chromates are oxidizers and chromium(VI) compounds are hazardous; handling should follow standard inorganic chemical safety practices, including appropriate containment and personal protective equipment.

See also: cobalt chromate pigments; chromates; cobalt(II) salts; chromium(VI) compounds.