09160 IUPAC Gold Book - direct coulometry at controlled current 10.1351/goldbook.09160 09160 current 1 Coulometry at an imposed, constant electric current in the electrochemical cell. Direct coulometry at controlled current is usually carried out in convective mass transfer mode. The end-point of the electrolysis, at which the current is stopped, must be determined either from the inflection point in the \(E{-}t\) curve or by using visual or objective end-point indication, similar to volumetric methods. The total electric charge is calculated as the product of the constant current and time of electrolysis or can be measured directly using a coulometer. The advantage of this method is that the electric charge consumed during the electrode reaction is directly proportional to the electrolysis time. Care must be taken to avoid the potential region where another electrode reaction may occur. Coulometry https://goldbook.iupac.org//terms/view/09159 coulometer https://goldbook.iupac.org//terms/view/09157 electrochemical cell https://goldbook.iupac.org//terms/view/09058 PAC, 2020, 92, 641. 'Terminology of Electrochemical Methods of Analysis (IUPAC Recommendations 2019)' on page 683 (https://doi.org/10.1515/pac-2018-0109) https://goldbook.iupac.org/terms/view/09160/html https://goldbook.iupac.org/terms/view/09160/json https://goldbook.iupac.org/terms/view/09160/plain Citation: 'direct coulometry at controlled current' 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.09160 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. 2026-08-05T12:04:51+00:00