Potassium permanganate is an inorganic compound with the chemical formula KMnO4 and composed of K+ and MnO−4. It is a purplish-black crystalline salt, that dissolves in water to give intensely pink or purple.
Potassium permanganate is used extensively in the water treatment industry. It is used as a regeneration chemical to remove iron and hydrogen sulfide (rotten egg smell) from well water. It currently finds application in the control of nuisance organisms such as zebra mussels in fresh water collection and treatment systems
A solution of KMnO4 in water, in a volumetric flask
A major application of KMnO4 is as a reagent for the synthesis of organic compounds. Significant amounts are required for the synthesis of ascorbic acid, chloramphenicol, saccharin, isonicotinic acid, and pyrazinoic acid.
Potassium permanganate can be used to quantitatively determine the total oxidizable organic material in an aqueous sample. The value determined is known as the permanganate value. In analytical chemistry, a standardized aqueous solution of KMnO4 is sometimes used as an oxidizing titrant for redox titrations (permanganometry). As potassium permanganate is titrated, the solution becomes a light shade of magenta, which darkens as excess of the titrant is added to the solution. In a related way, it is used as a reagent to determine the Kappa number of wood pulp. For the standardization of KMnO4 solutions, reduction by oxalic acid is often used.
Aqueous, acidic solutions of KMnO4 are used to collect gaseous mercury in flue gas during stationary source emissions testing.
In histology, potassium permanganate was used as a bleaching agent.
Ethylene absorbents extend storage time of bananas even at high temperatures. This effect can be exploited by packing bananas in polyethylene together with potassium permanganate. By removing ethylene by oxidation, the permanganate delays the ripening, increasing the fruit's shelf life up to 4 weeks without the need for refrigeration
Potassium permanganate is sometimes included in survival kits: as a hypergolic fire starter (when mixed with glycerol antifreeze from a car radiator; as a water sterilizer - and for creating distress signals on snow.
Potassium permanganate is added to "plastic sphere dispensers" to create backfires, burnouts, and controlled burns. Polymer spheres resembling ping-pong balls containing small amounts of permanganate are injected with ethylene glycol and projected towards the area where ignition is desired, where they spontaneously ignite seconds later. Both handheld[and helicopter or boat-mounted plastic sphere dispensers are used.
Potassium permanganate is one of the principal chemicals used in the film and television industries to "age" props and set dressings. Its ready conversion to brown MnO2 creates "hundred-year-old" or "ancient" looks on Hessian cloth (burlap), ropes, timber, and glass.
In agricultural chemistry, it is used for estimation of available nitrogen in soil.