Hydroxide

Hydroxide in chemistry is a name given to the diatomic anion OH⁻, made up of oxygen and hydrogen atoms. Most chemical compounds that contain hydroxides are bases.

A space-filling model of a hydroxide ion

An Arrhenius base is a substance that when dissolved in an aqueous solution, it produces hydroxide ions. Therefore, hydroxide ions are heavily involved in acid-base reactions.

Many useful chemical reactions or processes involve hydroxide or hydroxide ions. Sodium hydroxide is used in industry as a strong base, potassium hydroxide is used in agriculture, and iron hydroxide minerals such as goethite and limonite have been used as iron ore. The aluminium ore bauxite is made mainly out of aluminium hydroxides.

Most inorganic hydroxide salts do not dissolve in water.

Uses of hydroxides

Many useful chemicals and chemical processes involve hydroxides or hydroxide ions. Sodium hydroxide is used in factories as an alkali, potassium hydroxide is used in farming, and iron hydroxide has been used as low grade brown iron ore.

Examples of hydroxides

• Sodium hydroxide (NaOH)
• Potassium hydroxide (KOH)
• Calcium hydroxide (Ca(OH)₂)
• Ammonium hydroxide (NH₄OH)