02938 IUPAC Gold Book - ideal mixture 10.1351/goldbook.I02938 I02938 current 1 A mixture of substances B, C, ... is called an ideal mixture when \(a_{\rm{B}}=x_{\rm{B}}\), \(a_{\rm{C}}=x_{\rm{C}}\), ... or \(f_{\rm{B}}=1\), \(f_{\rm{C}}=1\) where \(a_{\rm{B}}\) and \(f_{\rm{B}}\) are the relative activity and the activity coefficient, respectively, of a substance B in a liquid or solid mixture. activity coefficient https://goldbook.iupac.org//terms/view/A00116 relative activity https://goldbook.iupac.org//terms/view/R05256 PAC, 1994, 66, 533. 'Standard quantities in chemical thermodynamics. Fugacities, activities and equilibrium constants for pure and mixed phases (IUPAC Recommendations 1994)' on page 543 (https://doi.org/10.1351/pac199466030533) https://goldbook.iupac.org/terms/view/I02938/html https://goldbook.iupac.org/terms/view/I02938/json https://goldbook.iupac.org/terms/view/I02938/plain Citation: 'ideal mixture' 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.I02938 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. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . 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. 2026-07-02T18:29:20+00:00