Redox titration potential change required

Alternately, it is possible to strip the metal off by applying a constant anodic current through the electrode. The potential of the electrode, when monitored as a function of time, gives an experimental curve, analogous to a normal redox titration curve (Fig. 24.4), which contains the quantitative and qualitative information. A sudden change in the potential occurs when all the metal deposited in the electrode has been depleted from the surface. The time required to... 

For titrations of reductants with oxidants, a redox indicator is required to indicate when the potential of the solution has reached that at equivalence (B in Figure 1). For an observer to see that an indicator has fully changed color, it is generally taken that the ratio [Indred]/[Indox] needs to change from 1 10 to 10 1. Application of the Nernst equation shows that this involves a change of potential of 0.12/ i d V, that is 120 mV for a one-electron indicator or 60 mV for a two-electron indicator at room temperature. 

---