Hydroxide
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| Hydroxide | |
|---|---|
| Image:Hydroxide lone pairs-2D.svg | |
| Image:Hydroxide-3D-vdW.png | |
| IUPAC name | hydroxide |
| Systematic name | hydroxide oxidanide hydridooxygenate(1−) |
| Identifiers | |
| CAS number | |
| PubChem | |
| SMILES | [OH-] |
| InChI | InChI=1/H2O/h1H2/ p-1/fHO/h1h/q-1 |
| Properties | |
| Molecular formula | OH− |
| Molar mass | 17.00274 (7) g/mol |
| Acidity (pKa) | ~22 |
| Basicity (pKb) | -1.74 15.74 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references | |
In chemistry, hydroxide is the most common name for the diatomic anion OH−, consisting of oxygen and hydrogen atoms, usually derived from the dissociation of a 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)2)
- Ammonium hydroxide (NH4OH)
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, NH3:
NH3(g) + H2O(l) ⇌ NH4+(aq) + OH−(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 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
by omitting spectator ions.
Solubility
Most inorganic hydroxide salts are insoluble in water, except for those with cations from Group I, NH4+, Ba2+, Sr2+, Ca2+ (little) or Tl+.
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 pairs of electrons, behaving as a Lewis base. Examples of complexes containing such a ligand include the aluminate ion [Al(OH)4]− and aurate ion [Au(OH)4]−.
See also
Notes
ca:Grup hidroxil cs:Hydroxid da:Hydroxid de:Hydroxidioneo:Hidroksila grupo fr:Groupement hydroxyle hr:Hidroksidi id:Hidroksida is:Hýdroxýl it:Idrossido he:הידרוקסיל la:Hydroxydatum lt:Hidroksidas mk:Хидроксид nl:Hydroxylgroep ja:水酸化物sk:Hydroxid sr:Хидроксид fi:Hydroksidi sv:Hydroxidjon tl:Hydroxide uk:Гідроксид vi:Hiđrôxít
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
