Acid-Base Titration
Virtual Lab Bench
Observations
pH Curve
The Chemistry
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
In an acid-base titration, the base (NaOH) is slowly added to the acid from a burette. The pH is monitored as the reaction proceeds. At the equivalence point, stoichiometric amounts of acid and base have reacted. The indicator changes colour to signal this point.
About Acid-Base Titrations
A titration is a quantitative analytical technique used to determine the concentration of a solution by reacting it with a solution of known concentration. In an acid-base titration, a base is gradually added to an acid (or vice versa) until the equivalence point is reached, where stoichiometric amounts have reacted.
The shape of the pH curve differs for strong acid/strong base titrations compared to weak acid/strong base titrations. Strong acid titrations show a sharp jump at pH 7, while weak acid titrations show a more gradual change with the equivalence point above pH 7 due to hydrolysis of the conjugate base. Choosing the correct indicator is important as its colour change range must overlap with the steep region of the pH curve.