Consider the titration of 100.0 mL 0.1 M KOH with 1.0 M HBr. Find the pH at the following volumes of acid (Va) added: Va= 0, 1, 10 and 10.1 mL.

Answer 1

First determine the volume for the equivalence point.
For zero mL you have a solution of KOH only. Since that is a strong base and is 100% ionized, solve for OH and convert to pH.
At the equivalence point, the pH is determined by the hydrolysis of the salt.
At all points before the equivalence point, pH is due to excess OH^-.
At all point after the equivalence oint the pH is determined by the excess HBr.
For before and after the equivalence point points, remember to take into account the dilution of the KOH or HBr.