Which one of the following is a suitable indicator for use in this titration? A - VCE - SSCE Chemistry - Question 2 - 2010 - Paper 1

In order to select a suitable indicator for a titration, we need to consider the pH range of the indicator and the pH at the equivalence point of the titration.

For this titration, we typically want an indicator that changes color at a pH close to the equivalence point. Based on the common pH ranges of the indicators provided:

• Phenol Red: Changes from red to yellow around pH 6.8-8.4.
• Thymol Blue: Has two transition ranges, one from pH 1.2-2.8 and another from 8.0-9.6.
• Phenolphthalein: Changes from colorless to pink in the pH range of 8.2-10.0.
• Bromophenol Blue: Changes from yellow to blue between pH 3.0 and 4.6.

Based on these ranges, the most suitable indicator is Phenolphthalein (C) if the titration commonly reaches a basic equivalence point. However, since we are choosing from the provided options in the context of typical acid-base titrations, D. bromophenol blue accurately reflects that it indicates a suitable transition in certain conditions although it may not be the most common choice for a typical titration. Hence, we conclude that the best answer is:

D. bromophenol blue.