potassium hydroxide

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potassium hydroxide,

chemical compound with formula KOH. Pure potassium hydroxide forms white, deliquescent crystals. For commercial and laboratory use it is usually in the form of white pellets. A strong base, it dissolves readily in water, giving off much heat and forming a strongly alkaline, caustic solution (see acids and basesacids and bases,
two related classes of chemicals; the members of each class have a number of common properties when dissolved in a solvent, usually water. Properties
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). It is commonly called caustic potash. It closely resembles sodium hydroxide in its chemical properties and has similar uses, e.g., in making soap, in bleaching, and in manufacturing chemicals, but is less widely used because of its higher cost. It is prepared chiefly by electrolysis of potassium chloride; commercial grades of it sometimes contain the chloride as well as other impurities.

Potassium Hydroxide


caustic potash, KOH, a strong alkali; colorless crystals. Density, 2.12 g/cm3 (25°C); melting point, 380°C.

Potassium hydroxide is readily soluble in water (97 g per 100 g H2O at 0°C; 112 g at 20°C), liberating a considerable amount of heat. Potassium hydroxide is produced commercially in the form of an opaque solid white mass containing 90–92 percent KOH (representing a mixture of KOH and KOH·H2O). In the air, potassium hydroxide absorbs H2O and C02 and deliquesces, gradually converting to potassium carbonate K2C03. Potassium hydroxide has a destructive effect on skin, paper, wool, silk, and other organic materials; it causes severe burns on human skin and is particularly dangerous to the eyes. Safety goggles and rubber gloves must be worn when working with it. Potassium hydroxide is obtained by the electrolysis of calcium chloride solutions. Potassium hydroxide is used in the manufacture of liquid soaps, as a source material in the preparation of potassium salts, in alkaline batteries, and as a laboratory reagent.

potassium hydroxide

[pə′tas·ē·əm hī′dräk‚sīd]
(inorganic chemistry)
KOH Toxic, corrosive, water-soluble, white solid, melting at 360°C; used to make soap and matches, and as an analytical reagent and chemical intermediate. Also known as caustic potash; potassium hydrate.