| 单词 | dissociation constant |
| 释义 | > as lemmasdissociation constant 2. Chemistry. The direct separation of compound substances into their primary elements, or into less complex compounds; decomposition, spec. by the action of heat. Hence dissociation-point, the temperature at which such decomposition takes place; dissociation constant, the product of the concentrations of the dissociated ions in a solution divided by the concentration of the undissociated molecule when equilibrium has been reached. Applied usually to the separation of a compound into its elements by the action of heat alone, without the intervention of any substance which breaks up the combination by its greater chemical affinity for one of the elements; but sometimes restricted to such a partial separation of the elements, that they reunite when the temperature is lowered below the dissociation-point. Others have used it in the wider etymological sense of direct separation of elements by any force, and applied thermolysis n. to dissociation by heat, as distinguished from electrolysis n. or decomposition by electricity. ΘΚΠ the world > matter > chemistry > chemical reactions or processes > [noun] > chemical reactions or processes (named) > separation > specific separation processes departa1626 parting1662 inquart1683 departure1741 disassociation1814 dialysis1861 dissociation1869 inquartation1881 1857 H. Ste. Claire Deville in Jrnl. de l'Institut Nov. 23 (title) De la dissociation, ou décomposition spontanée des corps, sous l'influence de la chaleur.] 1869 C. A. Joy in Scientific Opinion (article) On Dissociation. 1872–5 H. Watts Dict. Chem. VII. 636 As ‘Dissociation’ might be applied equally well to the separation of a mass into its constituent particles..by any other means, Mohr proposes to replace it by the more specific term ‘Thermolysis’. 1874 W. R. Grove On Correlation Physical Forces (ed. 6) 52 The term ‘dissociation’ has been applied..to other cases, in which heat separates the constituents of a substance without any of them combining with another body. 1880 Times 1 Dec. 10 Mr. Norman Lockyer continues his researches on dissociation, as indicated in solar outbursts. 1880 Nature 11 Mar. 445/2 [The] term dissociation-point is justified by analogy with the terms boiling-point and melting-point. 1891 Jrnl. Chem. Soc. 60 i. 257 The author..communicates his determination of the dissociation constants of some 60 organic substances of acid character. 1955 J. G. Davis Dict. Dairying (ed. 2) 418 The degree of dissociation is thus a measure of the strength of the acid or alkali, a very strong acid like hydrochloric or a very strong alkali like caustic soda being practically completely dissociated in dilute solution. The degree of dissociation is expressed in terms of the dissociation constant. < as lemmas |
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