Kaliumkromaatti

Kaliumkromaatti, or potassium chromate, is an inorganic salt with the formula K2CrO4. It consists of two potassium ions and the chromate anion (CrO4)2-, in which chromium is in the +6 oxidation state. The compound appears as yellow crystals or powder and is readily soluble in water. In solution it forms chromate ions that impart a characteristic yellow color.

Chemically, potassium chromate is a hexavalent chromium compound and acts as an oxidizing agent under certain conditions. It is sensitive to reducing agents and can react with acids to form Cr(VI) species in solution. The salt is hazardous to handle and should be stored in a cool, dry place in a tightly closed container, away from incompatible materials such as strong reducing agents.

Uses of kaliumkromaatti are mainly historical and analytical. It has been used as a yellow pigment in paints, plastics, and coatings. In qualitative inorganic analysis it serves as a reagent to detect lead(II) ions: when chromate is added to a solution containing lead, insoluble lead chromate (PbCrO4) precipitates as a bright yellow solid. It can also appear in certain laboratory and industrial processes as an oxidizing component or as part of chromate-based treatment systems, though its use has declined due to safety concerns with hexavalent chromium.

Safety and environmental considerations are central to its handling. Potassium chromate is toxic and a confirmed carcinogen (Cr(VI)); exposure can irritate skin, eyes, and the respiratory tract. It is harmful to aquatic life. Use appropriate protective equipment, work in ventilation, and dispose of it as hazardous waste, typically via reduction of Cr(VI) to Cr(III) before disposal in accordance with local regulations.