Question

In acid-base titration react rapidly to neutralise each other. Equivalence point is a point at which the acid and the base (or oxidising agent and reducing agent) have been added in equivalent quantities. The end point is the point at which the titration stops. Since the purpose of the indicator is to stop the titration close to the point at which the acid and base were added in equivalent quantities, it is important that the equivalent point and the end point be as close as possible. The indicator must change colour at a pH close to that of a solution of the salt of the acid and base. Significantly, the pH changes most rapidly near the equivalence point. The exact shape of a titration curve depends on $K_a$ and $K_b$ of acid and base.

The suitable indicator for the titration is

• A. Methyl orange
• B. Bromothymol
• C. Methyl red
• D. All of these

Answer 1

The correct option is D All of these

The suitable indicator for the titration is Methyl orange (pH range 3.0-4.4), Bromothymol (pH range 6 to 7.6)
and Methyl red (pH range 4.2-6.3).