Pre-lab 4.4 Cyclic Voltammetric Analysis of

If you are comfortable with the information in Appendix 2, continue by reviewing the plot description of the well-behaved Fe(CN)64- 3 system below. You will need to repeat this result before moving on to your AA substituted complexes (Fig. 4.6). 

Important Parameters Anodic peak current, zpa cathodic peak current, zpc anodic peak potential, /ipa, cathodic peak potential, Epc. 

Fe(CN)63- + e- Fe(CN)64-Rapid rise in current, almost instantaneous reduction at 

The above description of the redox reaction for Fe(CN)64- -/3 is a textbook example because the system nicely obeys Nemstian conditions and many cycles can be repeated without distortion of the voltammogram (we call this a reversible system) electron transfer is rapid and reversible at the electrode surface and complete concentration polarization is achieved under conditions of 1 m KNO3. We know this is a reversible system because ipa/ /pc 1. For a rigorous check on this condition, a plot of ip vs vl,/2 should be linear (where v — scan rate), equation (4.5). 

Further evidence for good reversibility is that the peak separation, A/i p, is close to 60 mV for this one electron transfer process, equation (4.6), and is independent of v. For a two-electron transfer, this separation should be 30 mV, etc. 

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