Natriumdichromaat

Natriumdichromaat, or sodium dichromate, is an inorganic compound with the formula Na2Cr2O7. It appears as bright orange to orange-red crystals that are highly soluble in water and hygroscopic. In aqueous solution, it contains hexavalent chromium and forms chromate-dichromate equilibria; under acidic conditions it can generate chromic acid. It is a strong oxidizing agent and reacts readily with reducing agents and many organic materials.

Uses and applications include oxidation in chemical synthesis, and historic uses in chrome plating and metal finishing, wood preservation, and textile dyeing. It has also served in analytical chemistry as a standard oxidant and in certain photographic processes. Due to safety and environmental concerns, many applications have declined or been replaced with less hazardous alternatives.

Safety and handling are important due to its toxicity and chromium(VI) content. Sodium dichromate is highly toxic and considered a human carcinogen; exposure can irritate the skin, eyes, and respiratory tract, and ingestion can be fatal. It is corrosive and should be handled with appropriate personal protective equipment in a well-ventilated area, with measures to prevent environmental release. Storage should be in tightly closed containers, away from organic materials and incompatible acids or reducing agents.

Regulatory and environmental aspects note that sodium dichromate poses hazards to aquatic life and can persist in the environment. Regulatory restrictions on chromium(VI) compounds limit its use in several jurisdictions, and there is a trend toward substituting it with chromate- or dichromate-free alternatives in many sectors.