Title: efflorescence
Long Title: IUPAC Gold Book - efflorescence
DOI: 10.1351/goldbook.E01909
Status: current

Definition
The reverse of deliquescence: the drying of a salt solution when the vapour pressure of water in the saturated solution of a substance is greater than the partial pressure of water in the ambient air. Also refers to the loss of water of crystallization from a solid salt such as $\ce{Na2CO3.10H2O}$ .

Related Terms
- crystallization: https://goldbook.iupac.org//terms/view/C01434
- deliquescence: https://goldbook.iupac.org//terms/view/D01582
- partial pressure: https://goldbook.iupac.org//terms/view/P04420
- salt: https://goldbook.iupac.org//terms/view/S05447
- saturated solution: https://goldbook.iupac.org//terms/view/S05471

Source
- PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2186 (https://doi.org/10.1351/pac199062112167)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/E01909/html
- json: https://goldbook.iupac.org/terms/view/E01909/json
- xml: https://goldbook.iupac.org/terms/view/E01909/xml

Citation: Citation: 'efflorescence' 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.E01909
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.
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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: 2026-05-08T23:47:56+00:00