30.0 mL of KOH will have been added after six titrations. Therefore, the equivalence point will be reached during the sixth titration.
(4) What is the pH at the equivalence point?
The pH at the equivalence point should be 7, since the titration is between a strong acid and a strong base. At the equivalence point, the concentration of the hydronium ions from the acid is so small that the autoionization of water must be considered when calculating pH. In fact, the concentration of hydronium ions from the acid is negligible compared to the concentration from the water autoionization. Therefore, the pH value comes from the water autoionization, yielding a value of 7.
(5) What indicator would be appropriate for this titration?
An appropriate indicator for this titration is one that has a color change around pH=7, such as bromothymol blue.
