Term: extent of reaction, \(\xi\)
https://doi.org/10.1351/goldbook.E02283

Definition:
extensive quantity describing the progress of a chemical reaction equal to the number of chemical transformations, as indicated by the reaction equation on a molecular scale, divided by the Avogadro constant (it is essentially the amount of chemical transformations). The change in the extent of reaction is given by dξ = dnB/νB, where νB is the stoichiometric number of any reaction entity B (reactant or product) and dnB is the corresponding amount.

Related Terms:
1) extensive quantity (http://doi.org/10.1351/goldbook.E02281).
2) avogadro constant (http://doi.org/10.1351/goldbook.A00543).
3) amount (http://doi.org/10.1351/goldbook.A00297).
4) stoichiometric number (http://doi.org/10.1351/goldbook.S06025).

Source: Green Book, 2nd ed., p. 43 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)

Citation: 'extent of reaction, \(\xi\)' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.E02283

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