Permanganate
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2008-06-30T13:00:50Z
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[[Image:Permanganate-anion-2D.png|thumb|right|200px|The structure of the manganate(VII) anion]]
A permanganate is the general name for a [[chemical compound]] containing the '''manganate(VII)''' [[ion]], (MnO<sub>4</sub><sup>−</sup>). Because manganese is in the +7 [[oxidation state]], the manganate(VII) ion is a strong oxidizer.
In an [[acid]]ic solution, manganate(VII) is reduced to the colourless +2 oxidation state of the [[Manganese|Manganese(II)]] (Mn<sup>2+</sup>) ion.
:16 [[hydronium|H<sub>3</sub>O<sup> + </sup>]] + 2 MnO<sub>4</sub><sup>−</sup> + 10 [[chloride|Cl<sup>−</sup>]] → 2 [[manganese|Mn<sup>2+</sup>]] + 5 [[chlorine|Cl<sub>2</sub>]] + 24 H<sub>2</sub>O <br>
:6 [[hydronium|H<sup>+</sup>]] + 2 MnO<sub>4</sub><sup>−</sup> + 5 HCOOH → 8 H<sub>2</sub>O + 2 [[manganese|Mn<sup>2+</sub>]] + 5 [[carbon dioxide|CO<sub>2</sub>]]
In a [[base (chemistry)|bas]]ic solution, manganate(VII) is either reduced to the brown +4 oxidation state of MnO<sub>2</sub> or to the green +6 oxidation state of MnO<sub>4</sub><sup>2−</sup>.
:4 [[hydroxide|OH<sup>−</sup>]] + 2 MnO<sub>4</sub><sup>−</sup> + 3 [[oxalate|C<sub>2</sub>O<sub>4</sub><sup>2−</sup>]] → 2 [[manganese(IV) oxide|MnO<sub>2</sub>]] + 6 [[carbonate|CO<sub>3</sub><sup>2−</sup>]] + 2 H<sub>2</sub>O
:3 [[hydroxide|OH<sup>−</sup>]] + 2 MnO<sub>4</sub><sup>−</sup> + [[bisulfite|HSO<sub>3</sub><sup>−</sup>]] → 2 [[manganate|MnO<sub>4</sub><sup>2−</sup>]] + [[sulfate|SO<sub>4</sub><sup>2−</sup>]] + 2 H<sub>2</sub>O
==Production==
Permanganates may be produced by oxidation of [[manganese]] compounds by strong oxidizing agents, for instance, [[sodium hypochlorite]] or [[lead dioxide]]:
:2 [[manganese chloride|MnCl<sub>2</sub>]] + 5 [[sodium hypochlorite|NaClO]] + 6 [[sodium hydroxide|NaOH]] → 2 [[sodium permanganate|NaMnO<sub>4</sub>]] + 9 NaCl+ 3 H<sub>2</sub>O <br>
:2 [[manganese sulfate|MnSO<sub>4</sub>]] + 5 [[lead dioxide|PbO<sub>2</sub>]]+ 3 [[sulfuric acid|H<sub>2</sub>SO<sub>4</sub>]] → 2 HMnO<sub>4</sub>+ 5 PbSO<sub>4</sub> + 2 H<sub>2</sub>O
Or by [[dismutation]] of [[manganate]]s:
:3 Na<sub>2</sub>MnO<sub>4</sub> + 2 H<sub>2</sub>O → 2 [[sodium permanganate|NaMnO<sub>4</sub>]] + [[manganese dioxide|MnO<sub>2</sub>]] + 4 NaOH
==Properties==
Manganates(VII) are [[salt]]s of [[permanganic acid]]. Manganate(VII) is a strong [[oxidizer]], and similar to [[perchlorate]]. It is therefore in common use in qualitative analysis that involves redox reactions(permanganometry).Besides this, it is stable.
It is a useful reagent, though with organic compounds, it may just destroy them entirely.
Manganates(VII) are not very thermically stable. For instance, [[potassium permanganate]] decomposes at 230 °C:
:2 [[potassium permanganate|KMnO<sub>4</sub>]] → [[potassium manganate|K<sub>2</sub>MnO<sub>4</sub>]] + [[manganese dioxide|MnO<sub>2</sub>]] + [[oxygen|O<sub>2</sub>]]
==Compounds==
* [[Calcium permanganate]], Ca(MnO<sub>4</sub>)<sub>2</sub>
* [[Potassium permanganate]], KMnO<sub>4</sub>
* [[Sodium permanganate]], NaMnO<sub>4</sub>
See [[:Category:Permanganates|category]] for a bigger list.
==External links==
*[http://www.npi.gov.au/database/substance-info/profiles/52.html National Pollutant Inventory - Manganese and compounds Fact Sheet]
*Companies that use permanganate to remediate hazardous chemicals:[http://www.orinrt.com ORIN]
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