Argentometry

In analytical chemistry, argentometry is a type of titration involving the silver(I) ion.

Calcium acetate "fixes" free chlorine, precipitates carbonates, and neutralizes the resultant solution.

Past the equivalence point, excess silver(I) ions adsorb on the AgCl surface, imparting a positive charge.

Anionic dyes such as dichlorofluorescein are attracted to the particles, and undergo a colour change upon adsorption, representing the end-point.

Eosin (tetrabromofluorescein) is suitable for titrating against bromide, iodide, and thiocyanate anions, giving a sharper end-point than dichlorofluorescein.

Determining chlorides in water by the Mohr method. Potassium chromate is added as indicator in an Erlenmeyer flask and the end of the reaction is determined by the slight red color given by the silver chromate.