Hydroxide 13711 221908146 2008-06-26T17:06:45Z Rifleman 82 1255637 restore images [[Image:Hydroxide lone pairs-2D.svg|thumb]] [[Image:Hydroxide-3D-vdW.png|thumb]] In [[chemistry]], '''hydroxide''' is the most common name for the [[Diatomic molecule|diatomic]] [[anion]] OH<sup>−</sup>, consisting of [[oxygen]] and [[hydrogen]] [[atom]]s, usually derived from the [[Dissociation (chemistry)|dissociation]] of a [[base (chemistry)|base]]. It is one of the simplest diatomic ions known. [[Inorganic]] compounds that contain the [[hydroxyl]] group are referred to as hydroxides. Common hydroxides include: *[[Sodium hydroxide]] (NaOH) *[[Potassium hydroxide]] (KOH) *[[Calcium hydroxide]] (Ca(OH)<sub>2</sub>) ==Hydroxide as a base== Most compounds containing hydroxide are bases. An [[Arrhenius base]] is a substance that produces hydroxide ions when dissolved in [[aqueous solution]]. One example would be [[ammonia]], NH<sub>3</sub>: NH<sub>3</sub>(g) + H<sub>2</sub>O(l) {{unicode|⇌}} [[ammonium|NH<sub>4</sub><sup>+</sup>]](aq) + OH<sup>−</sup>(aq) Thus, hydroxide ions are heavily involved in [[acid-base]] reactions as well as the special double displacement reaction called [[neutralization]]. Salts containing hydroxide are called [[Strong salts|base salts]]. Base salts will dissociate into a cation and one or more hydroxide ions in water, making the solution basic. Base salts will undergo [[neutralisation reactions]] with [[acids]]. In general [[acid-alkali reactions]] can be simplified to :OH<sup>−</sup>[[Aqueous|(aq)]] + [[hydronium|H<sup>+</sup>]](aq) → [[water (molecule)|H<sub>2</sub>O]][[liquid|(l)]] by omitting [[spectator ion]]s. ==Solubility== Most inorganic hydroxide salts are [[insoluble]] in water, except for those with cations from [[Alkaline metal|Group I]], [[Ammonium|NH<sub>4</sub><sup>+</sup>]], [[Barium|Ba<sup>2+</sup>]], [[Strontium|Sr<sup>2+</sup>]], [[Calcium|Ca<sup>2+</sup>]] (little) or [[Thallium|Tl<sup>+</sup>]]. ==Applications== Hydroxides and hydroxide ions are relatively common. Many useful chemicals and chemical processes involve hydroxides or hydroxide ions. [[Sodium hydroxide]] (lye) 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 low grade ''brown'' [[iron ore]]. The [[aluminium]] ore [[bauxite]] is composed largely of aluminium hydroxides. ==Ligand== The hydroxide ion is a kind of [[ligand]]. It donates [[lone pair]]s of electrons, behaving as a [[Lewis base]]. Examples of complexes containing such a ligand include the aluminate ion [Al(OH)<sub>4</sub>]<sup>−</sup> and aurate ion [Au(OH)<sub>4</sub>]<sup>−</sup>. ==See also== {{Wiktionary}} *[[Hydronium]] *[[Oxide]] *[[Hydroxyl]] *[[Hydroxy]] ==Notes== * [http://pubs3.acs.org/acs/journals/doilookup?in_doi=10.1021/j100016a003 Solvation and Transport of H<sub>3</sub>O<sup>+</sup> and OH<sup>−</sup> Ions in Water (JCP 99, 5749 (1995)] <references/> [[Category:Hydroxides| ]] [[Category:Bases]] [[Category:Oxoanions]] [[Category:Water chemistry]] [[ar:هيدروكسيد]] [[cs:Hydroxid]] [[da:Hydroxid]] [[de:Hydroxidion]] [[es:Hidróxido]] [[hr:Hidroksidi]] [[id:Hidroksida]] [[it:Idrossido]] [[la:Hydroxidum]] [[lt:Hidroksidas]] [[mk:Хидроксид]] [[nl:Hydroxylgroep]] [[ja:水酸化物]] [[pl:Jon wodorotlenowy]] [[ru:Гидроксиды]] [[sk:Hydroxid]] [[sr:Хидроксид]] [[fi:Hydroksidi]] [[sv:Hydroxidjon]] [[tl:Hydroxide]] [[vi:Hiđrôxít]] [[uk:Гідроксид]] [[zh:氢氧根]]