Permanganate



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 Mn 2+ + 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 KMnO4 → K2MnO4 + MnO2 + O2

Compounds

 * Potassium permanganate, KMnO4
 * Sodium permanganate, NaMnO4

See category for a bigger list.