Skip to main content

activity coefficient

activity coefficient (γ) The ratio of chemical activity (i.e. the effective concentration, a) of a component in a solution, to the actual mole fraction (X) present in solution: (γ = a/X). Values for activities are determined experimentally in a number of ways, including measuring the ratio of the vapour pressure (p) of a known concentration of the substance in solution to the vapour pressure (p*) of the pure substance: a = p/p*. In an ideal solution the activity coefficient = 1, and the activity of the component is equal to its mole fraction. In general, the greater the amount of dissolved material, the lower the activity coefficients of each of the species present.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"activity coefficient." A Dictionary of Earth Sciences. . Encyclopedia.com. 16 Nov. 2018 <https://www.encyclopedia.com>.

"activity coefficient." A Dictionary of Earth Sciences. . Encyclopedia.com. (November 16, 2018). https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/activity-coefficient

"activity coefficient." A Dictionary of Earth Sciences. . Retrieved November 16, 2018 from Encyclopedia.com: https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/activity-coefficient

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.