Hidroxids

Hidroxids, commonly called hydroxides, are chemical compounds that contain the hydroxide group (OH−) and are typically formed by metal cations coordinated to hydroxide. They are usually produced when metal oxides react with water or by precipitation from solutions of metal salts with bases. Inorganic hydroxides include alkali metal hydroxides such as sodium hydroxide (NaOH) and potassium hydroxide (KOH), and alkaline earth metal hydroxides such as calcium hydroxide (Ca(OH)2) and barium hydroxide (Ba(OH)2). Many hydroxides are insoluble in water, while alkali metal hydroxides and some alkaline earth hydroxides dissolve to give strongly basic solutions. Some hydroxides, such as aluminum hydroxide (Al(OH)3) and zinc hydroxide (Zn(OH)2), are amphoteric, dissolving in both acids and bases.

Preparation is commonly achieved by reacting oxides with water, by neutralizing metal salts with bases, or by hydration of oxides (for example, CaO + H2O → Ca(OH)2). Properties typically include white, crystalline solids; strong basicity for soluble hydroxides; and varying solubility. Upon heating, many hydroxides decompose to oxides and water, and some react with carbon dioxide to form carbonates, especially the more soluble hydroxides such as NaOH and KOH.

Uses are broad: alkali and alkaline earth hydroxides are essential in chemical manufacturing, paper production, cement and lime industry, water treatment, and soap making (saponification). They are also used for pH control and neutralization processes. Safety considerations reflect their caustic and corrosive nature; handling requires protective equipment and proper storage to prevent skin and eye injury.