This Demonstration shows the process of titration of a solution with an unknown concentration of with . Titration is based on the reaction: . The titration curve is used to find the unknown concentration of .

Adding a volume of to the solution of at an unknown initial concentration for the reaction gives:

Here (in mL) is the volume of the solution of , (in mol/L) is the unknown concentration of that needs to be found, (in mol/L) is the known concentration of , and (in mL) is the volume of used to reach equilibrium with .

When , the potential depends on the species and : .

When , the species determines the potential: .

The potential change at the equivalence point could be used to determine the volume , so the unknown concentration of can be calculated using the relation: .