The purpose of this lab is to determine the molar concentration of a strong acid solution by titrating measured volumes with a strong base 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. A titrant, a reagent of known concentration, is used to react with a measured volume of the reactant.
In this experiment, the titrant is NaOH and the reactant is HCl. The concentration of NaOH was determined in the previous experiment. HCl is the strong acid and NaOH is a base. Acid-base reactions are neutralization reactions and the product is water. When a basic solution is added to an acidic one of known concentration, hydroxide ions from the base react with the hydronium ions fro mthe acidic solution. This creates water. The pH measures the molarity of the hydronium ions. When the number of moles of hydroxide ions added is equal to the moles of hydronium ions, the pH jumps sharply. This is when the equivalence point is reached which is this volume of NaOH that is needed to reaction with HCl in a stoichiometric ratio.
When the NaOH is titrated with HCl, the volume of NaOH needed to react with HCl in a stoichiometric ratio can be found. With that information, the number of moles of NaOH can be found. HCl and NaOH react in a 1:1 ratio so the number of moles of NaOH in the reaction is the same as the number of moles of HCl. After calculation the number of moles of HCl, the concentration can be found be found because the volume of HCl is measured out to 20.00 mL.