Potassium is chemically very like sodium, but it even more reactive. It has one natural radioactive isotope, K40, which has a half-life of 1.28 billion years. K40 decays into Ar40, an isotope of argon; the relative amounts of each are used to date ancient rocks in a technique called potassium-argon dating. The most common isotope is K39 (93.1%).
Potassium salts (see below) are essential to plant life (hence their use in fertilizers), and are important in animals for the transmission of impulses through the nervous system (see sodium-potassium pump.
Potassium saltsPotassium carbonate (K2CO3) is a hygroscopic, white or colorless, crystalline solid, produced commercially by electrolysis of potassium chloride, followed by treatment of the resulting potassium hydroxide with carbon dioxide. It is an alkali used as a fertilizer, to make glass, soap, and dyes, and in cleaning and electroplating metals.
Potassium chloride (KCl) is a white or colorless crystalline solid, extracted from lake brines and from minerals such as sylvite, kainite, and carnakkite. It is used as a fertilizer and as a raw material in the production of potassium carbonate and potassium hydroxide.
Potassium hydroxide (KOH), also called caustic potash, is a white crystalline solid prepared commercially by electrolysis of potassium chloride. It is a strongly alkaline substance used for making soaps and detergents.
Potassium (VII) manganate (KMnO4), also called potassium permanganate, is a purple, soluble, crystalline solid made from pyrolusite (manganese dioxide) and potassium hydroxide. It is used as an oxidizing agent, disinfectant, dye, and in the preparation of other chemicals. Relative density 2.70; decomposes at 240°C (464°F).
Potassium nitrate, also called saltpeter or niter, is a colorless crystalline solid, soluble in water, which decomposes to give off oxygen when heated to 400°C. It is made from sodium nitrate and potassium chloride by fractional crystallization, and is used in gunpowder, matches, fireworks, some rocket fuels, and as a fertilizer (for its nitrogen content) and food preservative.
Potassium sodium tartrate tetrahydate (Rochelle salt) KNaC4H4O6.4H2O) is a colorless, crystalline compound that can be prepared from baking soda and cream of tartar (crystallized potassium hydrogen bitartrate). It is used in baking powders and as a laxative, and also in electronics for the piezoelectric effect. It is named after La Rochelle, France, where it was first discovered.
Related category INORGANIC CHEMISTRY
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