What is precipitation titration?
Precipitation titration is the process of forming a precipitate during titration.
Suppose we want to standardize a solution of silver nitrate by titrating against a standard solution of KCl. The silver electrode was used as an indicator electrode for the titration. Ag+, Ag potential of half-cell is measured by connecting it with the calomel electrode.
Silver nitrate solution titrated against a standard solution of KCl strength of this solution is about ten times higher. As the reaction starts, the Ag+ ion slowly precipitates as silver chloride.
The concentration of Ag+ ions decreases, and the potential of the Ag+, Ag electrode given by the Nernst equation,
The electrode potential will change slowly by adding KCl and more rapidly at the endpoint. The endpoint concentration of Ag+ ions is minimal, and the change in electrode potential is maximum at the endpoint.
After the endpoint, if the addition of KCl is continued does not affect the concentration of Ag+ ions. Only a small change in the electrode potential.
The precipitation titration curve was obtained similarly to an acid-base titration curve, see figures (a) & (b)
Figure (a) Potentiometric titration curve obtained in precipitation titration.
Figure (b) Determination of endpoint in precipitation titration.
