What Is Potassium Permanganate?
Potassium permanganate is an inorganic chemical used for several household and industrial purposes. It is a common oxidizing reagent that can be used to remove odors and metals from water systems. Its chemical formula is KMnO4, which consists of the K+ potassium ion combined with the MnO4 manganese compound. Potassium permanganate is a very useful salt, but should be handled with care as its pure form is toxic to humans.
Potassium permanganate is a strong oxidizing compound and is usually used in water treatment plants to precipitate iron and manganese from drinking water. The ions are converted into hydroxides, which then sink to the bottom of the treatment tank. It is also used to remove musty or earth-smelling odors from drinking water, and for treating sulfur smells. Its use in the beginning stages of water treatment may reduce disinfection byproducts caused by water chlorination. Potassium permanganate can also help control invasive water mollusks, like zebra mussels and the Asiatic clam.
Common Household Uses
Potassium permanganate is a mild disinfectant. It is used to treat fungal infections like athlete's foot and is also used for other skin maladies like eczema. The salt is a preservative that florists can use as a preservative to extent the life of fresh cut flowers. It is also helpful in controlling algae blooms. Historically, potassium permanganate was used to disinfect drinking water, but now more powerful disinfectants are usually needed.
Industrial uses of potassium permanganate include metal cleaning, tanning, and bleaching. In analytical chemistry, the salt is used as an indicator in wet bench titration methods. On the other hand, organic chemistry uses potassium permanganate to recognize double or triple bonds in a molecule. The KMnO4 solution used is called Baeyer's reagent.
Potassium permanganate in its pure form is a dark purplish black crystalline solid. It will dissolve in water, sulfuric acid and acetone. It has a molecular weight of 158.03 and is commonly referred to as permanganic acid, potassium salt and Condy's crystals. The solid will melt at 240 degrees Celsius, has a specific gravity of 2.7 and a vapor density of 5.4. It is a strong oxidizer.
Pure potassium permanganate is toxic to humans. It can be fatal if swallowed, can cause burns if placed on skin, and will ignite if exposed to flame. KMnO4 crystals should not be inhaled, touched or ingested. Use gloves and protective goggles if handling the pure salt. Diluted potassium permanganate is useful for a wide variety of applications, but the concentration should be checked by a physician before applying to the skin.
- George Doyle/Stockbyte/Getty Images