Difference between revisions of "Hexavalent chromium"

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(Created page with "{{Stub}} '''Hexavalent chromium''' ('''chromium(VI)''', '''Cr(VI)''' or '''chromium 6''') refers to chemical compounds that contain the element chromium in the +6 oxidation st...")
 
(Neutralization)
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===Neutralization===
 
===Neutralization===
Chromium(VI) compounds can be converted to the less harmful Cr(III) using reducing agents. [[Ascorbic acid]], sodium/potassium/ammonium sulfite/thiosulfate/metabisulfite are very effective, and being readily available and cheap, are excellent neutralization agents.
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Chromium(VI) compounds can be converted to the less harmful Cr(III) using reducing agents. [[Ascorbic acid]], sodium/potassium/ammonium sulfite/thiosulfate/metabisulfite are very effective, and being readily available and cheap, are excellent neutralization agents. [[Sugar]]s, like [[glucose]] and [[fructose]], can also be used, and they're even cheaper.<ref>https://www.technologyreview.com/s/407647/neutralizing-toxic-chromium-with-sugar/</ref>
  
Chromic acid should first be diluted in lots of water, before neutralization, to limit splashing an aerosolization.
+
Chromic acid, and chromium trioxide should first be diluted in a large volume of water, before neutralization, to limit splashing and aerosolization of Cr(VI). Chromium(VI) pentoxide is very unstable and will rapidly break down, though it's best to add some reducing agent to the solution to remove any potential traces of Cr(VI).
  
 
==References==
 
==References==

Revision as of 15:17, 17 March 2018

Hexavalent chromium (chromium(VI), Cr(VI) or chromium 6) refers to chemical compounds that contain the element chromium in the +6 oxidation state (thus hexavalent).

Properties

Hexavalent chromium compounds are brightly colored, yellow, orange or red. They are soluble in water, though chromium trioxide and chromyl chloride will react with water. They are powerful oxidizers, though chromates and dichromates will need an acid to initiate the reaction.

Notable compounds

Preparation

Cr(VI) compounds like dichromates can be prepared by oxidizing an aqueous mixture of chromium(III) hydroxide with hypochlorite or hydrogen peroxide.

Uses

Safety

Hexavalent chromium is recognized as a human genotoxic carcinogen. Exposure to hexavalent chromium increases the risk of developing lung cancer, asthma, or damage to the nasal epithelia and skin.

Within the European Union, the use of hexavalent chromium in most applications is regulated by the Restriction of Hazardous Substances Directive.

Neutralization

Chromium(VI) compounds can be converted to the less harmful Cr(III) using reducing agents. Ascorbic acid, sodium/potassium/ammonium sulfite/thiosulfate/metabisulfite are very effective, and being readily available and cheap, are excellent neutralization agents. Sugars, like glucose and fructose, can also be used, and they're even cheaper.[1]

Chromic acid, and chromium trioxide should first be diluted in a large volume of water, before neutralization, to limit splashing and aerosolization of Cr(VI). Chromium(VI) pentoxide is very unstable and will rapidly break down, though it's best to add some reducing agent to the solution to remove any potential traces of Cr(VI).

References

  1. https://www.technologyreview.com/s/407647/neutralizing-toxic-chromium-with-sugar/

Relevant Sciencemadness threads