Environmental Impact and Health Effects of Potassium
Environmental Impact and Health Effects of Potassium
With symbol K (from Latin kalium, “alkali”) and atomic number 19, Potassium is a chemically reactive and extremely soft metallic elements placed in group 1 of the periodic table. The element’s name comes from the English word potash, a potassium compound originally obtained by soaking wood ash in a pot of water and allowing the water to evaporate. Most potassium occurs in the Earth’s crust as minerals, such as feldspars and clays. Potassium is leached from these by weathering, which explains why there is quite a lot of this element in the sea (0.75 g/liter). Minerals mined for their potassium are pinkish and sylvite, carnallite and alunite. The main mining area used to be Germany, which had a monopoly of potassium before the First World War. Today most potassium minerals come from Canada, USA and Chile. The world production of potassium ores is about 50 million tonnes, and reserves are vast.
The metal is silvery white and can be cut with a knife but oxidizes rapidly in air and tarnishes within minutes, so it is generally stored under oil or grease. It is light enough to float onto water with which it reacts instantly to release hydrogen that burns with a lilac flame. Potassium exists in three natural isotopic forms, with mass numbers 39, 40, and 41. Potassium-40 is radioactive and has a half-life of 1.26 billion years. The most abundant isotope is potassium-39. Several radioactive isotopes have been artificially prepared. Potassium melts at about 63°C (about 145°F), boils at about 760°C (about 1400°F), and has a specific gravity of 0.86; the atomic weight of potassium is 39.098.The chemistry of potassium is almost entirely that of its ion, K+.
Potassium metal is prepared by the electrolysis of fused potassium hydroxide or of a mixture of potassium chloride and potassium fluoride. The metal oxidizes as soon as it is exposed to air and reacts violently with water, yielding potassium hydroxide and hydrogen gas. Potassium is found in nature in large quantities, ranking eighth in order of abundance of the elements in Earth’s crust, in various minerals. Potassium is a constituent of all plant and animal tissue as well as a vital constituent of fertile soil.
Potassium forms many compounds resembling corresponding sodium compounds, based on a valence of 1. A few of the element’s most important compounds are: Potassium bromide (KBr), a white solid formed by the reaction of potassium hydroxide and bromine; Potassium chromate (K2CrO4), a yellow crystalline solid, and potassium bichromate, or potassium dichromate (K2Cr2O7), a red crystalline solid, are powerful oxidizing agents used for many industrial purposes; Potassium iodide (KI), a white crystalline compound that is very soluble in water, is used in photography for preparing gelatin emulsions and in medicine for the treatment of rheumatism and over activity of the thyroid gland; Potassium nitrate (KNO3), a white
