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Absorption _chemistry_


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									Absorption (chemistry)
From Wikipedia, the free encyclopedia

   Other senses: for the amalgamation of gold into mercury, see absorption of gold into mercury. For the absorption of light,
   see Absorption (electromagnetic radiation).
In chemistry, absorption is a physical or chemical phenomenon or a process
in which atoms, molecules, or ions enter some bulk phase – gas, liquid, or
solid material. This is a different process from adsorption, since molecules
undergoing absorption are taken up by the volume, not by the surface (as in
the case for adsorption). A more general term is sorption, which covers
absorption, adsorption, and ion exchange. Absorption is a condition in which
something takes in another substance.[1]
If absorption is a physical process not accompanied by any other physical or
chemical process, it usually follows the Nernst partition law:
   "the ratio of concentrations of some solute species in two bulk phases in
   contact is constant for a given solute and bulk phases" [citation needed] :

The value of constant KN depends on temperature and is called partition
coefficient. This equation is valid if concentrations are not too large and if the
species "x" does not change its form in any of the two phases "1" or "2". If
such molecule undergoes association or dissociation then this equation still
describes the equilibrium between "x" in both phases, but only for the same
form – concentrations of all remaining forms must be calculated by taking into           Laboratory absorber. 1a): CO 2 inlet; 1b): H2 O
account all the other equilibria.[1]                                                       inlet; 2): outlet; 3): absorption column; 4):
In the case of gas absorption, one may calculate its concentration by using,
e.g., the Ideal gas law, c = p/RT. In alternative fashion, one may use partial
pressures instead of concentrations.
In many processes important in technology, the chemical absorption is used in place of the physical process, e.g., absorption
of carbon dioxide by sodium hydroxide – such acid-base processes do not follow the Nernst partition law.
For some examples of this effect, see liquid-liquid extraction. It is possible to extract from one liquid phase to another a solute
without a chemical reaction. Examples of such solutes are noble gases and osmium tetroxide.[1]

   1. ^ a b c McMurry, John (2003). Fundamentals of Organic               534-39573-2.
      Chemistry (Fifth ed.). Agnus McDonald. pp. 409. ISBN 0-

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