Chrome hexavalentvignette| Un composé de chrome hexavalent : l'oxyde de chrome(VI). Le chrome hexavalent, chrome(VI), Cr ou chrome 6 est le du chrome. Les produits qui en contiennent sont le plus souvent extrêmement toxiques. Presque tout le minerai de chrome est traité en passant par le stade « chrome hexavalent », en particulier le dichromate de sodium salé. Le chrome hexavalent est la clé de tous les matériaux fabriqués à partir de chrome.
Chromate and dichromateChromate salts contain the chromate anion, CrO42−. Dichromate salts contain the dichromate anion, Cr2O72−. They are oxyanions of chromium in the +6 oxidation state and are moderately strong oxidizing agents. In an aqueous solution, chromate and dichromate ions can be interconvertible. Potassium-chromate-sample.jpg|[[potassium chromate]] Potassium-dichromate-sample.jpg|[[potassium dichromate]] Chromates react with hydrogen peroxide, giving products in which peroxide, O22−, replaces one or more oxygen atoms.
Galvanic corrosionGalvanic corrosion (also called bimetallic corrosion or dissimilar metal corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte. A similar galvanic reaction is exploited in primary cells to generate a useful electrical voltage to power portable devices. This phenomenon is named after Italian physician Luigi Galvani (1737-1798).
