What is the function of an indicator in a titration

Explanation:

Titration is a procedure that uses the properties of the acid - base reactions to determine the mole concentration of an unknown solution from the known mole concentraion of other solution. One of the solution is the base and the other is the acid.

At the equivalence point, where the number of H⁺ ions is equal to the number of OH⁻ ions, there is a drastic change of the acidity (or alkalinity) of the solution.

Then, the chemical indicators are substances that change color at the equivalence point, telling the chemist that the equivalence point has been reached and the titration has finished.