Sodium dichromate
Sodium dichromate is an inorganic chromium(VI) salt with formula Na₂Cr₂O₇. It is a strong oxidizing agent and a source of hexavalent chromium.
Dichromate ion: The polyatomic ion Cr₂O₇²⁻, in which two chromium(VI) centers are joined through an oxygen atom. This anion carries sodium dichromate’s chromium(VI) and is reduced during oxidation reactions.
Ionic compound: A substance composed of positively and negatively charged ions held together by electrostatic attraction. Sodium dichromate is an ionic solid built from sodium cations and dichromate anions.
Chromic acid: An aqueous chromium(VI) oxidizing species, commonly represented by H₂CrO₄ and related ions. Sodium dichromate can generate chromic acid mixtures used for oxidation and surface treatment.
Sodium chromate: The yellow sodium salt of the chromate ion, Na₂CrO₄, containing chromium in the +6 oxidation state. It is a closely related chromium(VI) salt whose chromate ion predominates under less acidic conditions.
Hexavalent chromium: Chromium present in the +6 oxidation state, a class of compounds associated with severe health and environmental hazards. Sodium dichromate releases soluble chromium(VI), the source of its principal toxicological risks.
Redox reaction: A chemical reaction involving transfer of electrons and changes in oxidation states. Sodium dichromate oxidizes other substances by accepting electrons in redox reactions.
Sodium ion: The positively charged monatomic ion Na⁺, formed when a sodium atom loses one electron. Two sodium ions balance the charge of each dichromate ion in the formula.
Leather tanning: The processing of animal hides into durable leather through chemical stabilization of collagen. Dichromate has served as a chromium source in tanning, though safer chromium(III) processes are preferred.
Potassium dichromate: The orange chromium(VI) salt K₂Cr₂O₇, widely used as an oxidizing agent and analytical reagent. It supplies the same dichromate ion but differs in counterion, solubility, and common laboratory use.
Carcinogenicity of chromium(VI): The cancer-causing potential of certain chromium(VI) compounds, especially when inhaled occupationally. Exposure to sodium dichromate can contribute to chromium(VI)-related cancer risk.