Term: alkalinity
https://doi.org/10.1351/goldbook.09034

Definition:
Measure of the capacity of aqueous media to react with hydrogen ions.

Notes:
1) Alkalinity is used to assess the buffering capacity of natural waters and is measured by titration using methyl red (pH 4.5, total alkalinity) or phenolphthalein (pH 8.3, composite alkalinity).
2) Alkalinity is often expressed as an equivalent mass concentration of calcium carbonate, for example "alkalinity equals \(\pu{3.2 mg L-1}\) as \(\ce{CaCO3}\)."

Link: 
Related Term: composite alkalinity (http://doi.org/10.1351/goldbook.09038).

Source: PAC, 2025, 97, 137. 'Glossary of terms for mass and volume in analytical chemistry (IUPAC Recommendations 2024)' on page 2 (https://doi.org/10.1515/pac-2023-0903)

Citation: 'alkalinity' 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.09034

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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