Coulometry theory

Cyclic voltammetry has gained widespread usage as a probe of molecular redox properties. I have indicated how this technique is typically employed to study the mechanisms and rates of some electrode processes. It must be emphasized that adherence of the CV responses to the criteria diagnostic of a certain mechanism demonstrates consistency between theory and experiment, rather than proof of the mechanism, since the fit to one mechanism may not be unique. It is incumbent upon the experimenter to bring other possible experimental probes to bear on the question. These will often include coulometry, product identification, and spectroelectrochemistry. 

It is our belief that a full and detailed understanding of the electron-transfer properties of organometallic complexes can be achieved only by a combination of chemical and electrochemical studies the use of one alone can lead to erroneous conclusions. Because we have insufficient space to provide a discussion of the theory and practice of elementary electrochemical techniques we refer the reader to several excellent treatments which also include an explanation of commonly used terminology (25-30). The synthetic chemist should not be deterred from routinely using techniques such as cyclic voltametry (CV),1 voltametry at rotating metal disk electrodes, or controlled potential electrolysis (CPE), coulometry, and chronoamperometry. The proper employment of such techniques, for which instrumentation is readily available, should prove sufficient for all but the most detailed studies. 

The theory for the different reaction schemes involves ordinary (rather than partial) differential equations, because the electrolyzed solution is assumed to be essentially homogeneous (see Section 11.3.1). The concentrations are functions of t during the bulk electrolysis, but not of x. The measured responses in coulometry are the i-t curves and the apparent number of electrons app consumed per molecule of electroactive compound. From the quantity of electricity passed during the electrolysis Q t), app can be calculated as... 

Sine Wave Methods in the Study of Electrode Processes, Margaretha Sluyters-Rehbach and Jan El. Sluyters The Theory and Practice of Electrochemistry with Thin Layer Cells, A. T. Hubbard and F. C. Anson Application of Controlled Potential Coulometry to the Study of Electrode Reactions, Allen J. Bard and K. S. V. Santhanam... 

Coulometry, in the context of electroanalytical chemistry, can be taken to include the theory and practice of any analytical procedures that depend on Faraday s laws of electrochemical equivalence. Specifically, the analytical chemist is interested in the quantitative determination of chemical species by measurement of the quantity of electrical charge (in coulombs) necessary just to convert a known amount of that species from one oxidation state to another. 

In this section the theory and methodology of electro-analytical chemistry are explored. Chapter 22 provides a (general foundation for the study of subsequent chapters in this section. Terminology- and conventions of electrochemistry as well as theoretical and practical aspects of the measurement of electrochemical potentials and current s are. presented. Chapter 23 comprises the many methods and applications of potentiometry. and constant-potential coulometry and constant-current coulornetrv are discussed in Chapter 2 4. The many facets of the important and widely used technique of voltammetry are presented in ( hapter 2.5. which concludes the section. 

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