Sodium chromate

Sodium chromate (Na₂CrO₄) is a yellow, water-soluble inorganic salt containing chromium in the +6 oxidation state. It is used in chemical analysis, metal treatment, and manufacturing.

Chromate: Chromate is the tetrahedral CrO₄²⁻ oxyanion, in which chromium has the +6 oxidation state. This ion gives sodium chromate its chemical identity and characteristic yellow color.
Diphenylcarbazide test: The diphenylcarbazide test is a colorimetric method for detecting chromium(VI) in solution. Chromate can serve as a chromium(VI) source in analytical standards and sample chemistry.
Sodium: Sodium is a reactive alkali metal with atomic number 11 that commonly forms Na⁺ ions. Two sodium ions balance the charge of each chromate ion in Na₂CrO₄.
Hexavalent chromium: Hexavalent chromium comprises chromium compounds in the +6 oxidation state, many of which are toxic and carcinogenic. Sodium chromate belongs to this hazardous group and can release its soluble chromium(VI) ions.
Dichromate: Dichromate is the orange Cr₂O₇²⁻ oxyanion, also containing chromium in the +6 oxidation state. Acidic conditions shift chromate toward this differently colored, related ion.
Chromate conversion coating: A chromate conversion coating is a corrosion-resistant surface layer formed chemically on a metal. Sodium chromate has been used in treatments that deposit protective chromate films.
Chromium: Chromium is a metallic chemical element with atomic number 24 and several common oxidation states. It is the central atom in chromate and determines the compound's chromium(VI) hazards.
Chromium toxicity: Chromium toxicity is harmful biological effect caused by exposure to chromium compounds. Sodium chromate exposure can damage tissue and cause systemic poisoning.
Chromic acid: Chromic acid is the oxyacid H₂CrO₄, associated with chromium in the +6 oxidation state. Acidification of chromate solutions connects the salt to chromic-acid chemistry.
Corrosion inhibitor: A corrosion inhibitor is a substance that slows the chemical or electrochemical deterioration of a material. Chromate ions suppress corrosion on metals, though toxicity limits their use.

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