Figure 7.1 Flowing coulometry.

1. Figure 7.1 Flowing coulometry.

2. Figure 7.2 An example of the current-voltage curve resulting from a totally polarized working electrode, in this case a gold electrode in an aqueous potassium nitrate solution. The solvent-oxidation and solvent-reduction reactions occurring at extreme potentials are shown. Between them is the “window” within which other electrode reactions may be investigated.

3. Figure 7.3 The reductive and oxidative rate constants depend exponentially on electrode potential and share a common value at the formal potential. The reductive transfer coefficients α = 0.35 and α = 0.50were chosen for the red and green curves respectively

4. Figure 7.4 The oxidative current density and the reductive current density sum to give the measured net current density. At the null potential En the two partial current densities are identical in magnitude but opposite in sign.

5. Figure 7.5 The Tafel plot. The straight line portions occur where i ≈ ird and where i ≈ iox. The graph is curved close to the null potential En, where neither approximation holds. The construction lines show how the null potential and the composite exchange current density in may be measured.

6. Figure 7.6 A chart illustrating how the determination of a rate law is used to rule out certain putative mechanisms. Here Mechanism I is unacceptable, but II and III remain possibilities.