Question

how does observed pH from the indicator differ from the one obtained from the first derivative for acetic acid? which method is more accurate?

Answer 1

The equivalence volume can be located roughly using your titration curve; a better estimate can be made using the first derivative plot of this same curve . The derivative is simply the slope of the line (∆V/∆pH) at each point on the curve). The volume of base added at the equivalence point will correspond to the maximum derivative value.

There are two plots that are available as shown above. From the first graph you may not say the exact area where the sudden change is happening(Ph change) . but from the second graph, you need not to bother about that. it will appear as default.

Thank you and good luck .