Dissociation
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dissociation
[də‚sō·sē′ā·shən] (medicine)
Independent, uncoordinated functioning of the atria and ventricles.
(microbiology)
The appearance of a novel colony type on solid media after one or more subcultures of the microorganism in liquid media.
(physical chemistry)
Separation of a molecule into two or more fragments (atoms, ions, radicals) by collision with a second body or by the absorption of electromagnetic radiation.
(psychology)
The segregation of ideas from their affects or feelings, resulting in independent functioning of these components of a person's mental processes.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
Dissociation
the process by which molecules break up into a number of simpler particles—molecules, radicals, atoms, or ions. Three types of dissociation are generally distinguished: thermal dissociation, which takes place at elevated temperature (for example, N2O4 ⇄ 2NO2); electrolytic dissociation, which occurs when electrolytes are dissolved (the splitting of the molecules of electrolytes into ions, for example, KOH ⇄ K+ + OH-); and photochemical dissociation, which is observed under the action of light (for example, Cl2 + hγ → 2Cl, where hy is a quantum of light). A quantitative characteristic of dissociation is the degree of dissociation, which is the ratio of the number of molecules that have broken up to the total number of molecules.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.