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## Activity coefficient
An ## Additional recommended knowledgeThese examples can be understood by considering the chemical potential of each substance in the mixture. The chemical potential, μ where is the chemical potential in the standard state and x This is generalised to include non-ideal behaviour by writing when *a*_{B}=*x*_{B}γ_{B}
where γ Modifying mole fractions or concentrations by activity coefficients gives the Knowledge of activity coefficients is particularly important in the context of electrochemistry since the behaviour of electrolyte solutions is often far from ideal, due the effects of the ionic atmosphere. ## Measurement and prediction of activity coefficientsActivity coefficients may be measured experimentally or calculated theoretically, using the Debye-Hückel equation or extensions such as Davies equation For uncharged species, the activity coefficient γ - log
_{10}(γ_{0}) =*b**I*
This simple model predicts activities of many species (dissolved undissociated gases such as CO For water, the activity coefficient γ where ν is the number of ions produced from the dissociation of one molecule of the dissolved salt, ## References**^**Gold Book definition**^**C.W. Davies,*Ion Association*,Butterworths, 1962**^**I. Grenthe and H. Wanner,*Guidelines for the extrapolation to zero ionic strength*, http://www.nea.fr/html/dbtdb/guidelines/tdb2.pdf**^**SIT theory**^**J.N. Butler, "Ionic Equilibrium", John Wiley and Sons, Inc., 1998.**^**A.J. Elis and R.M. Golding, Am. J. Sci, 162, p 47-60, 1963.**^**S.D.Malinin, Geokhimiya, 3, p. 235-245, 1959.
Categories: Thermodynamics | Electrochemistry |
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Activity_coefficient". A list of authors is available in Wikipedia. |