Title: pressure
Long Title: IUPAC Gold Book - pressure
DOI: 10.1351/goldbook.P04819
Status: current
Index: quantity

Definition
Normal force acting on a surface divided by the area of that surface. For a mixture of gases the contribution by each constituent is called the 'partial pressure' \(p_{i} = x_{i} p\), where \(x_{i}\) is the amount fraction of the \(i\)th constituent and \(p\) is the total pressure.

Related Terms
- amount fraction: https://goldbook.iupac.org//terms/view/A00296
- constituent: https://goldbook.iupac.org//terms/view/C01281

Sources
- Green Book, 2nd ed., p. 12 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)
- PAC, 1996, 68, 957. 'Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)' on page 987 (https://doi.org/10.1351/pac199668040957)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/P04819/html
- json: https://goldbook.iupac.org/terms/view/P04819/json
- xml: https://goldbook.iupac.org/terms/view/P04819/xml

Citation: Citation: 'pressure' 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.P04819
License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.
Collection: If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .
Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-04-18T05:33:02+00:00