Inorganic compound, any soluble hydroxide ( 2015; OH) of the alkali metals : lithium , sodium , potassium , rubidium, and cesium .
More broadly, ammonium hydroxide (see ammonia ) and soluble hydroxides of the alkaline earth metals are also called alkalies. Strong bases that turn litmus paper blue, they react with acids to yield salts , are caustic, and in concentrated form corrode tissues. Sodium hydroxide ( caustic soda ) and potassium hydroxide (caustic potash) are very important industrial chemicals, used in the manufacture of soaps, glass, and many other products. The mineral trona, a compound of sodium carbonate and bicarbonate, is one naturally occurring alkali. It may be mined or recovered from dry lake beds.