![]() ![]() Caustic potash is also used for preparing many potassium salts, such as potassium carbonate (K 2CO 3), a water-absorbing substance used in making glass and textile dyes and for cleaning and electroplating metals. Electrolysis of potassium chloride yields potassium hydroxide, also called caustic potash, a water-absorbing substance used in making soaps and detergents. Potassium chloride (KCl) is used in preparing other potassium compounds and in fertilizers. Potassium compounds have many commercial uses. Most potassium is present in insoluble minerals, making it difficult to obtain, but it can be prepared commercially by electrolysis from some refinable minerals. They are frequently found as dry mineral deposits and as brines. Water-soluble potassium compounds are economically recovered. The major commercial source is salt deposits, but a small fraction is obtained from plant and animal sources. It is the seventh most-abundant element in the Earth’s crust and occurs in many silicate rocks and minerals. Potassium was discovered in 1807 by the English chemist Humphry Davy, who obtained it from molten potassium hydroxide, and was the first metal to be isolated by electrolysis. It is never found alone and is difficult to isolate from its compounds. Because of its high reactivity, potassium is stored submerged in mineral oil. Potassium reacts violently with water, yielding potassium hydroxide (KOH) and hydrogen gas (which ignites). Potassium reacts readily with the oxygen in air, producing a lavender flame and forming an oxide compound. The chemical properties of potassium are similar to those of sodium. The boiling point of potassium is (1,400 ☏, or 760 ☌). Its physical properties are similar to those of the other alkali metals-it is highly malleable and ductile and a good conductor of both heat and electricity, with a low melting point (145.90 ☏, or 63.28 ☌). It is a soft, white metal with a silvery luster. Potassium belongs to the family of elements known as the alkali metals, which constitute Group 1 (Ia) of the periodic table. ![]()
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