Acid - Base Titration

What is a Titration? A titration is a procedure used in chemistry to determine the concentration of an unknown acid or base. A titration uses a neutralization reaction and stoichiometry to calculate the concentration of the unknown solution.

Titration An example: A chemist titrates 25.0 mL of H 2 SO 4 with a solution of 1.25M NaOH. The end point is reached when 33.8mL of the NaOH is added.

Titration Identify the following components of the titration: NaOH H 2 SO 4

Titration Identify the following components of the titration: NaOH The “titrant” - this is the solution with the known concentration. It is also called the “standard” H 2 SO 4

Titration Identify the following components of this titration: NaOH The “titrant” - this is the solution with the known concentration. It is also called the “standard”. H 2 SO 4 The “unknown” - this is the solution with the unknown concentration. We determine this solution concentration by stoichiometry.

Titration What is the reaction equation? 2NaOH (aq) + 1H 2 SO 4(aq)  2H 2 O (l) + 1Na 2 SO 4(aq) This is a neutralization reaction. We reach the neutral point (also known as the equivalence point) when the moles of H + = moles of OH -.

Titration How do you know when the equivalence point is reached? You use an indicator solution that changes colour near the pH of the neutral point.