Apparatus for potentiometric titration:

The titrant is added in huge increments at the outset. As the end-point is approaching (as indicated by larger potential changes per addition), the increments are made smaller. Sufficient time must be allowed for the attainment of equilibrium after each addition of reagent. The Precipitation reactions might need various minutes for equilibration, particularly in the vicinity of the equivalence points. A closed approach to equilibrium is indicated when the measured protential ceases to drift by more than a few millivolts. Excellent stirring is frequently effective in hastening the achievements of equilibrium.

Figure: Typical apparatus for potentiometric titration

Number of commercial "potentiometric titration units" are available which comprise an electrode system (frequently a selection of electrode is offered) together with a special stand providing supports for the electrodes, and one or two burette holders.

The base of the stand incorporates in magnetic stirrer and in some cases a hot plate, so that if necessary the solution to be titrated may be heated. A separate unit embodies a potentiometer and a compact galvanometer or if the potentiometer is designed for the portion from the a.c. mains, a balance point indicator might be 'magic eye' electronic indicates similar to that used in mains operated conductivity bridges.