Potassium permanganate (KMnO₄) is an inorganic chemical compound composed of potassium (K⁺) and permanganate (MnO₄^-) ions. Its IUPAC name is potassium manganate(VII) because its manganese (Mn) atom is in the +7 oxidation state. It is also known as "permanganate of potash" and "Condy's crystals". The permanganate acts as a strong oxidizing agent. The molecular weight of potassium permanganate is 158.04 g/mol. As a solid, it forms deep purple prisms. It is purple when dissolved in an aqueous solution. It has a sweet taste and is odorless.

History

Potassium permanganate was discovered in 1659.

Early photographers used it as a component of flash powder.

Uses

Potassium permanganate is used as an oxidizing agent in many different kinds of chemical reactions in a laboratory and in industry. It is also used as a disinfectant and in deodorizers and dyes. It is used to treat some parasitic diseases of fish, and used in treatment of drinking water, as well as an antidote in phosphorus poisoning. It can be used as a reagent for the synthesis of many different kinds of chemical compounds. For example, a dilute solution of KMnO₄ can convert an organic compound with a carbon-carbon double bond into a diol (glycol) compound. It has also been used to make cocaine 100% pure. In analytical chemistry, a standardized solution of KMnO₄ is sometimes used as an oxidizing titrant for redox titrations due to its deep purple color. Reduced manganese solutions can turn light pink.

In a diluted solution, it can be used as a mouthwash (1/4%), or to disinfect the hands (1%).

When mixed with water, it is can also be used as a catalyst with T-Stoff for rocket propulsion. In this usage, it is known as Z-Stoff.

It is used as a reagent to determine the Kappa number of wood pulp.

Cautions

Solid KMnO₄ is a very strong oxidizer, which when mixed with pure glycerine, will cause a highly exothermic chemical reaction to take place. This reaction would turn red hot as a spontaneous "combustion" which would melt a glass or other container holding the reacting contents and could ignite anything flammable nearby. A reaction of this sort could take place when solid KMnO₄ is mixed with many kinds of organic materials. Aqueous solutions of KMnO₄ are much less dangerous, especially when diluted. Mixing solid KMnO₄ with concentrated sulfuric acid causes an explosion.

Potassium permanganate stains the hand and clothing and should be handled with care. Clothing stains may be washed away using acetic acid or hydrochloric acid. Skin stains go off within 48 hours. It causes corrosive burns on the skin, while swallowing it may lead to gastroenteritis. In addition, mixing solid KMnO₄ with concentrated hydrochloric acid generates lethal chlorine gas [1].

The DEA has restricted its use and sale.