Permanganate

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File:Permanganate-anion-2D.png
The structure of the manganate(VII) anion

A manganate(VII) is a chemical compound that contains the manganate(VII) ion (MnO4). Because manganese is in the +7 oxidation state, the manganate(VII) ion is a strong oxidizer.

In an acidic solution, manganate(VII) will reduce to the colourless +2 oxidation state of the Manganese(II) (Mn2+) ion.

16 H3O + + 2 MnO4 + 10 Cl → 2 Mn2+ + 5 Cl2 + 24 H2O
6 H+ + 2 MnO4 + 5 HCOOH → 8 H2O + 2 Mn2+</sub> + 5 CO2

In a basic solution, manganate(VII) will either reduce to the brown +4 oxidation state of MnO2 or to the green +6 oxidation state of MnO42−.

4 OH + 2 MnO4 + 3 C2O42− → 2 MnO2 + 6 CO32− + 2 H2O
3 OH + 2 MnO4 + HSO3 → 2 MnO42− + SO42− + 2 H2O

Production

Permanganates may be produced by oxidization of manganese compounds by strong oxidizing agents, for instance, sodium hypochlorite or lead dioxide:

2 MnCl2 + 5 NaClO + 6 NaOH → 2 NaMnO4 + 9 NaCl+ 3 H2O
2 MnSO4 + 5 PbO2+ 3 H2SO4 → 2 HMnO4+ 5 PbSO4 + 2 H2O

Or by dismutation of manganates:

3 Na2MnO4 + 2 H2O → 2 NaMnO4 + MnO2 + 4 NaOH

Properties

Manganates(VII) are salts of permanganic acid. Manganate(VII) is a strong oxidizer, and similar to perchlorate. Being a strong oxidiser it is in common use in qualitative analysis experiments involving 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 KMnO4K2MnO4 + MnO2 + O2

Compounds

See category for a bigger list.

External links

de:Permanganateit:Permanganatonl:Permanganaat

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