pH titration curves:

• Through inspection, the end point could be situated from the inflection point of the titration curve.
• That is the end point which corresponds to maximum rate of change of pH per unit volume of titrant added (0.05 cm³ or 0.1 cm³).
• The distinction of the end point rise as the reaction included becomes more nearly quantitative.
• Once the pH has been built for a given titration, it could be used to indicate subsequent end points for the same chemical reaction.
• The equivalence point could be more precisely situated from the 1st and 2nd derivative curves as described in Figure (b) and (c). Solutions more dilute than 10-3 M generally do not give satisfactory end points. This is limitation of pH metry and potentiometric titrations.

Figure: pH titration curves; (a) Normal curve; (b) First derivative curve; and (c) second derivative curve