Question

An indicator is weak acid (or base) having a conjugate base (or acid) with a significantly different colour. For the titration of a weak base, how would you choose an appropriate indicator?

1)Choose an indicator that has a pK_b close to pK_b of the base

2)Choose an indicator which changes colour anywhere in the pH range 0-7

3)Choose an indicator that has a pK_a close to pK_b of the base

4)Choose an indicator with a pK_b close to the pH of the titration at equivalence

5)Choose an indicator with a pK_a close to the pH of the titration at equivalence

Answer 1

Acid-base indicators, the Substances such as phenolphthalein, which can be used to determine the pH of a solution.