To use all functions of this page, please activate cookies in your browser.
With an accout for my.chemeurope.com you can always see everything at a glance – and you can configure your own website and individual newsletter.
- My watch list
- My saved searches
- My saved topics
- My newsletter
In electrochemistry, the Cottrell equation describes the change in electric current with respect to time in a controlled potential experiment, such as chronoamperometry. For a simple redox event, such as the ferrocene/ferrocenium couple, the current measured depends on the rate at which the analyte diffuses to the electrode. That is, the current is said to be "diffusion controlled." The Cottrell equation describes the case for an electrode that is planar.
Additional recommended knowledge
i = nFAcoO(DO)1/2/π1/2t1/2
Deviations from linearity in the plot of i vs t-1/2 sometimes indicate that the redox event is associated with other processes, such as assocition of a ligand, dissociation of a ligand, or a change in geometry.
In practice, the Cottrell equation simplifies to
Furthermore, (scan rate)1/2 is used in place of t-1/2. Typical scan rates are in the range 20 to 2000 mV/s.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Cottrell_equation". A list of authors is available in Wikipedia.|