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Hexavalent chromium (chromium(VI), Cr(VI), chromium 6) is any chemical compound that contains the element chromium in the +6 oxidation state (thus hexavalent). [1] It has been identified as carcinogenic, which is of concern since approximately 136,000 tonnes (150,000 tons) of hexavalent chromium were produced in 1985. [ 2 ]
Chromium(IV) oxide is used to manufacture magnetic tape used in high-performance audio tape and standard audio cassettes. [93] Chromium(III) oxide (Cr 2 O 3) is a metal polish known as green rouge. [94] [95] Chromic acid is a powerful oxidizing agent and is a useful compound for cleaning laboratory glassware of any trace of organic compounds. [96]
Chromium compounds are compounds containing the element chromium (Cr). Chromium is a member of group 6 of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium are rare, but do nevertheless occasionally exist. [3] [4]
PG&E used chromium 6, or hexavalent chromium (a cheap and efficient rust suppressor), in its compressor station for natural-gas transmission pipelines. [1] [3] Hexavalent-chromium compounds are genotoxic carcinogens. In 1993, legal clerk Erin Brockovich began an investigation into the health impacts of the contamination. A class-action lawsuit ...
The primary chromium ore is the mixed metal oxide chromite, FeCr 2 O 4, found as brittle metallic black crystals or granules. Chromite ore is heated with a mixture of calcium carbonate and sodium carbonate in the presence of air. The chromium is oxidized to the hexavalent form, while the iron forms iron(III) oxide, Fe 2 O 3:
Hexavalent chromium is a toxic metal, known to cause several health problems and is a carcinogen. Exposure to hexavalent chromium can cause irritation and problems in the respiratory tract, stomach, and small intestine. It is linked to several cancers, such as lung cancer, oral cancer, and intestinal cancer. [11]
Chromium(III) oxide is amphoteric. Although insoluble in water, it reacts with acid to produce salts of hydrated chromium ions such as [Cr(H 2 O) 6] 3+. [11] It is also attacked by concentrated alkali to yield salts of [Cr(OH) 6] 3−. When heated with finely divided carbon or aluminium, it is reduced to chromium metal: Cr 2 O 3 + 2 Al → 2 Cr ...
Soluble hexavalent chromium is the most common type of chromium in oceans, where over 70% of dissolved chromium in the ocean is found in oxyanions such as chromate (CrO 2− 4). Soluble trivalent chromium is also found in the oceans where complexation with organic ligands occurs. Chromium is estimated to have a residence time of