AskDefine | Define permanganate

Dictionary Definition

permanganate n : a dark purple salt of permanganic acid; in water solution it is used as a disinfectant and antiseptic

User Contributed Dictionary

English

Noun

permanganate
  1. any salt of permanganic acid, they are purple crystalline solids, mostly soluble in water; they are strong oxidizing agents
  2. potassium permanganate

Translations

salt of permanganic acid
potassium permanganate

Extensive Definition

A permanganate is the general name for a chemical compound containing 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) is reduced 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+ + 5 CO2
In a basic solution, manganate(VII) is either reduced 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 oxidation 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
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. 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 KMnO4K2MnO4 + MnO2 + O2

Compounds

See category for a bigger list.

External links

permanganate in German: Permanganate
permanganate in Spanish: Permanganato
permanganate in French: Permanganate
permanganate in Italian: Permanganato
permanganate in Japanese: 過マンガン酸塩
permanganate in Dutch: Permanganaat
permanganate in Portuguese: Permanganato
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