Ammonium hydroxide
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2008-07-05T07:16:32Z
Puppy8800
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{{main|ammonia}}
'''Ammonium hydroxide'''(NH<sub>3</sub>[aq]), also known as '''ammonia water''', '''aqua ammonia''', or '''aqueous ammonia''', is a solution of [[ammonia]] in water. Technically, the use of the term "ammonium hydroxide" is incorrect because such a chemical compound can not be isolated. However, this term does give a fair description of how an ammonia solution behaves, and is commonly used even by scientists and engineers.
==Chemistry==
In aqueous solution, ammonia deprotonates some small fraction of the water to give [[ammonium]] and [[hydroxide]] according to the following [[chemical equilibrium|equilibrium]]:
:NH<sub>3</sub> + H<sub>2</sub>O <math>\rightleftharpoons</math> NH<sub>4</sub><sup>+</sup> + OH<sup>−</sup>
With a base ionization constant (''K''<sub>b</sub>) of 1.8×10<sup>−5</sup>, in a 1M [[ammonia]] solution about 0.42% of the ammonia will gain protons to become [[ammonium]] ions (equivalent to a pH of 11.63).
Aqueous ammonia is used in traditional qualitative inorganic analysis. Like many amines, it gives a deep blue coloration with copper(II) solutions. Ammonia solution can dissolve silver residues, such as that formed from [[Tollens' reagent]].
Solutions of ammonium can also dissolve reactive metals such as zinc, with the liberation of hydrogen gas. When ammonium hydroxide is mixed with dilute [[hydrogen peroxide]] in the presence of a metal ion, such as Cu<sup>2+</sup>, the peroxide will undergo rapid decomposition.
==See also==
* [[Common chemicals]]
* [[Conjugate acid]]
==External links==
*[http://www.airgasspecialtyproducts.com/UserFiles/laroche/PDF/AAPhysical.pdf Ammonium hydroxide physical properties]
[[Category:Ammonium compounds]]
[[Category:Bases]]
[[da:Ammoniakvand]]
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[[es:Hidróxido de amonio]]
[[fr:Ammoniaque]]
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[[pl:Woda amoniakalna]]
[[pt:Hidróxido de amônio]]
[[ru:Гидроксид аммония]]
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