Fill the breaker with the solution whose concentration is unknown and record the volume. Add a drop of the indicator. Fill the buret with a known solution and record the volume.
Slowly add the solution from the buret into the beaker. Carefully monitor the beaker because when the solution turns a light pink, the reaction is complete.
When the reaction is complete, calculate how much solution from the buret has been used by subtracting the amount left in the buret from the original amount.
Find the concentration of the unknown solution by multiplying the volume of the solution in the buret used times it molarity. Then divide the result by the original volume in the beaker. For example, if 3ml of 1.0 M solution was added to 6ml of the unknown concentration, multiple three times 1.0 divided by six to get a concentration of 0.5 M for the unknown solution.