Title: extent of reaction
Long Title: IUPAC Gold Book - extent of reaction
DOI: 10.1351/goldbook.E02283
Status: current
Index: quantity

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 \(\mathrm{d}\xi =\frac{\mathrm{d}n_{\rm{B}}}{\nu _{\rm{B}}}\), where \(\nu _{\rm{B}}\) is the stoichiometric number of any reaction entity B (reactant or product) and \(\mathrm{d}n_{\rm{B}}\) is the corresponding amount.

Related Terms
- Avogadro constant: https://goldbook.iupac.org//terms/view/A00543
- Extensive quantity: https://goldbook.iupac.org//terms/view/E02281
- amount: https://goldbook.iupac.org//terms/view/A00297
- stoichiometric number: https://goldbook.iupac.org//terms/view/S06025

Sources
- Green Book, 2nd ed., p. 43 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)
- PAC, 1992, 64, 1569. 'Quantities and units for metabolic processes as a function of time (IUPAC Recommendations 1992)' on page 1572 (https://doi.org/10.1351/pac199264101569)
- PAC, 1993, 65, 2291. 'Nomenclature of kinetic methods of analysis (IUPAC Recommendations 1993)' on page 2295 (https://doi.org/10.1351/pac199365102291)
- PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 165 (https://doi.org/10.1351/pac199668010149)
- PAC, 1996, 68, 957. 'Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)' on page 973 (https://doi.org/10.1351/pac199668040957)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/E02283/html
- json: https://goldbook.iupac.org/terms/view/E02283/json
- xml: https://goldbook.iupac.org/terms/view/E02283/xml

Citation: Citation: 'extent of reaction' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.E02283
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Accessed: 2026-05-01T10:04:26+00:00