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| : "Precipitate" redirects here, for the [[Interpol (band)|Interpol]] [[EP]] see [[Precipitate (EP)]]
| | precipitate is the formation of a solid bypassing the liquid state from a gas |
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| '''Precipitation''' is the condensation of a [[solid]] from a [[solution]] during a [[chemical reaction]]. This occurs when the solution is [[supersaturated]], whereupon the solid forms from the solute phase, and usually sinks to the bottom of the solution.
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| This effect is useful in many industrial and scientific applications whereby a chemical reaction may produce a solid that can be collected from the solution by various methods (e.g. filtration, decanting, centrifuging). Precipitation from a [[solid solution]] is also a useful way to [[precipitation strengthening|strengthen]] [[alloy]]s.
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| An important stage of the precipitation process is the onset of [[nucleation]]. The creation of a hypothetical solid particle includes the formation of an interface, which requires some energy based on the relative [[surface energy]] of the solid and the solution. If this energy is not available, and no suitable nucleation surface is available, [[supersaturation]] occurs.
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| ==Cation sensitivity==
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| Precipitate formation is useful in detecting the type of [[cation]] in an unknown [[salt]]. To do this, an [[alkali]] first reacts with the unknown salt to produce a precipitate which is the hydroxide of the unknown salt.
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| To identify the cation, the colour of the precipitate and its solubility in excess are noted.
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| Similar processes are often used to separate chemically similar elements, such as the [[rare earth]] metals.
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| ==External links==
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| * http://www.hci.edu.sg/~limth/lessons/2002/qa/cations.htm
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| [[Category:Chemistry]]
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| [[de:Fällungsreaktion]]
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| [[es:Precipitado]]
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| [[ja:%E6%B2%88%E6%AE%BF]]
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| [[nl:Neerslag (scheikunde)]]
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Revision as of 06:51, 6 September 2005
precipitate is the formation of a solid bypassing the liquid state from a gas
