Title: free ion
Long Title: IUPAC Gold Book - free ion
DOI: 10.1351/goldbook.15402
Status: current

Definition
Ion whose behavior is independent of the influence of a counterion.

Notes
1) A free ion is a distinct kinetic entity, and its reactivity is usually different from that of an ion pair.
2) The behavior of a free ion may still be influenced by neighboring atoms or molecules.

Source
- PAC, 2008, 80, 2163. 'Glossary of terms related to kinetics, thermodynamics, and mechanisms of polymerization (IUPAC Recommendations 2008)' on page 2175 (https://doi.org/10.1351/pac200880102163)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/15402/html
- json: https://goldbook.iupac.org/terms/view/15402/json
- xml: https://goldbook.iupac.org/terms/view/15402/xml

Citation: Citation: 'free ion' 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.15402
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Accessed: 2026-04-18T06:51:11+00:00