How does potassium permanganate
Potassium permanganate is a dark purple, almost black crystals. When dissolved in water, depending on the concentration, it gives the solution from pale pink to deep purple hue. In hot water KMnO4 dissolves better. Crystals substances or highly concentrated solution in contact with the skin or mucous membranes may cause burns.
Chemical properties of potassium permanganate
Potassium permanganate – oxygen-containing potassium salt. As the cation K(+) corresponds to the strong base KOH, and the anion MnO4(-) – manganese strong acid HMnO4, salt KMnO4 is not hydrolyzed.
KMnO4 is a strong oxidizer. It easily oxidizes many inorganic and organic substances. Restoration products of potassium permanganate depend on the conditions in which the reaction proceeds. So, in an acidic medium it is restored to Mn(2+), in neutral – to MnO2 in alkaline – to MnO4(2-).
For example, if you add K2SO3 potassium sulfite to the acidified purple potassium permanganate solution, it is colorless because it is made of salt of Mn(II):
2KMnO4+5K2SO3+3H2SO4=2MnSO4+6K2SO4+3H2O.
This is qualitative reaction on the ion MnO4(-).
How to recognize manganese oxide(IV) MnO2
Oxide manganese(IV) MnO2 is one of the most important compounds of this metal. It's a brown-black oxide, insoluble in water, the main component of the pyrolusite. In the same way as KMnO4, MnO2 is a strong oxidant that is used, for example, upon receipt of chlorine:
MnO2+4HCl=MnCl2+Cl2↑+2H2O.
The brown precipitate MnO2 falls under the action of potassium sulfite K2SO3 in a neutral permanganate solution. The oxidation state of manganese changes from +7 to +4:
2KMnO4+3K2SO3+H2O=2MnO2↓+3K2SO4+2KOH.
The restoration of the permanganate to manganate in an alkaline environment
In a strongly alkaline medium, if the concentration of alkali, potassium permanganate is reduced by potassium sulfite to manganate K2MnO4:
2KMnO4+K2SO3+2KOH=2K2MnO4+K2SO4+H2O.
The purple color of the solution changes to green. Manganate potassium – manganese compound, stable in alkaline medium.
The use of potassium permanganate
Potassium permanganate is widely used as oxidant in chemical laboratories and industry. 0.1% solution is used in medicine and in the home for disinfecting, rinsing, treatment of burns, removal of toxins.
