Acid-base titration, 2 of 5. pH meter is used in acid-base titration. The beaker initially contains an acidic solution with unknown concentration (0.1M hydrochloric acid, HCl, was used here). The pH meter reads pH=1. The burette contains a base, 0.1M solution of sodium hydroxide, NaOH (Photo 1). The base is added to the acidic solution (Photo 2) and the beaker is periodically swirled to mix the solution (Photo 3), while the pH increase is observed. When pH reaches 7 (equivalence point), i.e. solution becomes neutral (Photo 4), the volume of the base used is recorded and the initial concentration of the acidic solution is calculated. When base is added in access beyond the equivalence point, the pH of the solution continues to increase (Photo 5). |