02805 IUPAC Gold Book - heterogeneous diffusion rate constant 10.1351/goldbook.H02805 H02805 current 1 Defined by the equation: \[k_{\rm{d}}=\frac{I_{\rm{l}}}{n\ F\ c\ A}\] where the limiting current \(I_{\rm{l}}\) is assumed to be due to the diffusion species of concentration \(c\) and of diffusion coefficient \(D\). \(n\) is the charge number of the cell reaction written so that the stoichiometric coefficient of this species is unity. \(A\) is usually taken as the geometric area of the electrode, and \(F\) is the Faraday constant. Faraday constant https://goldbook.iupac.org//terms/view/F02325 charge number of the cell reaction https://goldbook.iupac.org//terms/view/C00995 coefficient https://goldbook.iupac.org//terms/view/C01124 diffusion https://goldbook.iupac.org//terms/view/D01716 diffusion coefficient https://goldbook.iupac.org//terms/view/D01719 limiting current https://goldbook.iupac.org//terms/view/L03532 stoichiometric https://goldbook.iupac.org//terms/view/S06021 PAC, 1974, 37, 499. 'Electrochemical nomenclature' on page 513 (https://doi.org/10.1351/pac197437040499) https://goldbook.iupac.org/terms/view/H02805/html https://goldbook.iupac.org/terms/view/H02805/json https://goldbook.iupac.org/terms/view/H02805/plain Citation: 'heterogeneous diffusion rate constant' 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.H02805 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. 2026-07-24T02:26:23+00:00