CaCrO4

CaCrO4, commonly known as calcium chromate, is an inorganic salt composed of calcium ions (Ca2+) and chromate ions (CrO4^2−). The compound typically forms as a pale yellow solid and is encountered in hydrated forms in commercial materials. In water it dissociates to yield Ca2+ and CrO4^2− ions, with chromium in the Cr(VI) oxidation state.

Chemically, chromate can interconvert with dichromate (Cr2O7^2−) under changes in pH, particularly toward acidic conditions. Calcium chromate is an oxidizing agent and should be handled with care. As a chromate salt, it is used as a pigment and as a corrosion inhibitor, especially in coatings designed to protect steel and reinforced concrete from corrosion.

Industrial uses of calcium chromate include serving as a yellow pigment in paints and coatings and acting as a corrosion-inhibiting additive in concrete and metal surfaces. It also appears as a reagent in some chemical syntheses and can serve as a precursor to other chromium compounds.

Preparation and handling typically involve precipitation from solutions containing calcium ions and chromate ions, such as mixing calcium salts with soluble chromate salts or by neutralizing chromic acid. Safety considerations are important: Cr(VI) compounds are toxic and carcinogenic, and calcium chromate is an oxidizer. Handling requires appropriate protective equipment and waste disposal in accordance with hazardous-wac regulations to minimize environmental and health risks.