Introduction and Background

      The purpose of this lab was to determine the concentration of a sodium hydroxide solution by titrating it with a standard solution of known concentration. Titration is a common technique that is used to determine the quantity of one reactant when the quantity of the other reactant is known. Once the solutions react in stoichiometric ratios the equivalence point is reached. The equivalence point tells the experimenters the volume of the unknown concentration of the reactant that is needed for the two solutions to react in a stoichiometric ratio. With this information and the number of moles in the known solution, the concentration of the unknown solution can be found.

     In this experiment the solution with the unknown concentration is NaOH. NaOH is hygroscopic and it readily absorbs moisture from the air. Because of this the exact concentration of the NaOH cannot be determined based on the mass. To determine the exact concentration, NaOH is titrated with a solution of known concentration and moles, KHP. When the volume of NaOH  added is stoichiometrically required there will be a large jump in the pH. That shows that the equivalence point has been reached.