Results for hydroxide
On this page:
 
Dictionary:

hydroxide

  (hī-drŏk'sīd') pronunciation
n.

A chemical compound containing the hydroxyl group.


 
 
Sci-Tech Encyclopedia: Hydroxide

A compound containing the hydroxide ion (OH−) and having the general formula M(OH)n, where M represents a metal. Hydroxides are a subset of compounds containing the hydroxyl group (OH) and range in chemical character from strongly basic, to amphoteric (having both acidic and basic characteristics), to essentially acidic. The hydroxide ion has a closed-shell electronic structure with a singlet ground state.

In the Lewis acid-base scheme, where a base is defined as an electron pair donor and an acid as an electron pair acceptor, a typical hydroxide decreases in base strength as attraction for electrons of the cation increases. For example, the hydroxides of electropositive elements such as the alkali metals and alkaline earths tend to be bases. When these ionic compounds are dissolved in water, they form metal ions and hydroxide ions, as in
1 {\rm M^+(OH^-)}_n{\rm (S)} + n{\rm H_2O}\longrightarrow {\rm M}^{n+}{\rm (aq)} + n{\rm OH}^-{\rm (aq)}
reaction (1), where S represents a solid and aq represents a water solution. The hydroxides of nonmetals (X) such as boron hydroxide [B(OH)3], where the X-O bonds are covalent, are generally acidic, as shown in reaction (2), where H3O+
2 {\rm X(OH)}_n + n{\rm H_2O}\longrightarrow {\rm XO}^{n-}_n{\rm (aq)} + n\rm H_3O^+(aq)
is the hydronium ion. The amphoteric hydroxides may dissociate by either mechanism, depending on the presence of strong acids or bases. See also Acid and base; Hydrogen ion.

The alkali metal hydroxides such as sodium hydroxide (NaOH) are extremely important as reagents in metallurgy and photography and in the manufacture of soaps and detergents. Calcium hydroxide [Ca(OH)2], known as slaked lime, is used in the preparation of mortar for brick laying. Minerals such as brucite [Mg(OH)2] and pyrochroite [Mn(OH)2] are naturally occurring hydroxides.

 
Dental Dictionary: hydroxide

n

An ionic compound that contains the OH2 ion, usually consisting of metals or the metal equivalent of the ammonium cation (NH42) that inactivates an acid.

 
Britannica Concise Encyclopedia: hydroxide

Any compound with one or more functional groups made up of one atom each of hydrogen and oxygen, bonded together and acting as the hydroxide anion (OH-). Hydroxides include the familiar alkalies of laboratory and industrial processes. Those of the alkali metals (lithium, sodium, potassium, rubidium, and cesium), the strongest bases, are the most stable and soluble; those of the alkaline earth metals (calcium, barium, and strontium), also soluble strong bases, are less stable. The hydroxides of most other metals are only slightly soluble but neutralize acids; some are "amphoteric," reacting with both acids and bases. In compounds in which OH is un-ionized and covalently bonded (e.g., in methanol, CH3OH), it is known as a hydroxyl group.

For more information on hydroxide, visit Britannica.com.

 
Columbia Encyclopedia: hydroxide
(hīdrŏk'sīd) , chemical compound that contains the hydroxyl (−OH) radical. The term refers especially to inorganic compounds. Organic compounds that have the hydroxyl radical as a functional group are called alcohols; the hydroxyl radical is also present in the carboxyl group of organic acids. Most metal hydroxides are bases—they form solutions that have an excess of OH− ions and a pH greater than 7, neutralize acids, and change the color of litmus from red to blue. Alkali metal hydroxides such as sodium hydroxide are strong bases and are very soluble in water; alkaline–earth metal hydroxides such as calcium hydroxide (slaked lime) are much less soluble in water and are not as strongly basic. Magnesium hydroxide (milk of magnesia) is only slightly basic. Some hydroxides (e.g., aluminum hydroxide) exhibit amphoterism, having either acidic or basic properties depending on the reaction in which they are involved. The hydroxides of some nonmetallic elements are acidic; the hydroxide of sulfur, S(OH)6, spontaneously loses two molecules of water to form sulfuric acid, H2SO4. Ammonium hydroxide, NH4OH, is a weak base known only in the solution that is formed when the gas ammonia, NH3, dissolves in water.

 
Veterinary Dictionary: hydroxide

The OH− anion or a compound containing the OH− ion.

 
Wikipedia: hydroxide
Hydroxide
Hydroxide_lone_pairs-2D.svg
Hydroxide-3D-vdW.png
IUPAC name hydroxide
Systematic name hydroxide
oxidanide
hydridooxygenate(1−)
Identifiers
CAS number 14280-30-9
PubChem 961
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:

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

OH−(aq) + H+(aq) → H2O(l)

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

Hydroxide ion is a kind of ligand. It donates lone pair 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


    This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

     
    Shopping: hydroxide
    Aluminum Hydroxide
     
     

    Join the WikiAnswers Q&A community. Post a question or answer questions about "hydroxide" at WikiAnswers.

     

    Copyrights:

    Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
    Sci-Tech Encyclopedia. McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.  Read more
    Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.  Read more
    Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 2006 Encyclopædia Britannica, Inc. All rights reserved.  Read more
    Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/  Read more
    Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
    Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hydroxide".  Read more

    Search for answers directly from your browser with the FREE Answers.com Toolbar!  
    Click here to download now. 

    Get Answers your way! Check out all our free tools and products.

    On this page:   E-mail   print Print  Link  

     

    Keep Reading

    Mentioned In:

     |  More >More >
     

    Do you have the answers?