Potassium permanganate and potassium iodine are both salts that contain potassium. However, the similarities end there. Solid potassium permanganate, abbreviated KMnO4, forms small blue-black crystals. Solid potassium iodide, abbreviated KI, forms white crystals. Potassium permanganate is used in water treatment plants. Potassium iodide is used by salt manufacturers. Neither should be used by the home consumer.
Chemistry
Potassium permanganate is a strong oxidizer. It takes electrons from other molecules in an exothermic or heat-generating reaction. In small amounts, potassium permanganate oxidizes certain molecules and causes them to precipitate out of solution. In large amounts, it is an explosive. Potassium iodide is far more stable than potassium permanganate. It doesn't react with other chemicals as easily. However, the iodine atoms dissociate easily, forming elemental iodine. The addition of sugar to salt prevents this from happening prematurely.
Water Treatment
Water is treated before reaching your tap to remove offensive tastes and smells. Two culprits are iron and manganese. Potassium permanganate oxidizes iron and manganese found in water, causing them to precipitate out. In addition, potassium permanganate also acts as a mild disinfectant that kills organisms, such as juvenile Asiatic clams and zebra mussels, that can be in the water supply.
Nutrition
Salt companies add potassium iodide to table salt as a public health measure to prevent iodine deficiency. Iodine is part of various thyroid hormones. Iodine deficiency is the most common cause of preventable brain damage throughout the world, as it is associated with mental retardation, developmental abnormalities and other disorders.
Medical Uses
While potassium permanganate was used to treat gonorrhea in the past, this approach was abandoned with the discovery of antibiotics. It also has mild antiseptic properties. Potassium iodide can used to prevent radioactive poisoning, either from medical applications of radioactivity or during nuclear emergencies. Administering potassium iodine prevents the update of radioactive iodine by the thyroid.
