The aim of this lab is to determine the concentration of a potassium hydrogen phthalate solution (HKC8O4H4) using acid‐base titration.
Introduction: Titration is a technique that chemists use to determine the unknown concentration of a known solution (we know what chemical is dissolved, but not how much in a solution). Because we know what the chemical is, we know how it will react with other chemicals and we can use that reaction to determine the concentration of the solution by measuring the formation of product(s). In the case of an unknown concentration of acid, we can use a known concentration of hydroxide base. This type of reaction is a neutralization reaction, where salt and water are products of the reaction:
Acid + Base Salt +
…show more content…
These calculations are outlined below. You may want to refer to your notes from lecture for additional examples. Determination of moles of base delivered: After each titration, you will need to determine the number of moles of sodium hydroxide used. First, you will need to know the molarity of the solution (the solution has been previously standardized, meaning it has a very accurate molarity that has been experimentally determined). Write this down when you start the titration. Next, you must determine the volume of the solution delivered to reach the equivalence point. Next, you will find the moles of base used in the titration:
*Note that the volume of base is in L, not in mL
Determine number of moles of HCl in flask: If you write the balanced reaction for the neutralization of sodium hydroxide and hydrochloric acid, you will see that the reaction proceeds in a 1:1 fashion. That is, for every hydroxide (OH‐) ion added, it can neutralize exactly one hydronium (H+) ion. This is not always the case for neutralization reactions, and is thus not always the case for acid‐base titrations. The general formula is below, where the determined moles of base from the equation above are multiplied by the stoichiometric ratio found by looking at the balanced