Question

A solution is tested with the four indicator solutions shown in the attached colour chart. The following results are obtained: Thymol blue turns yellow. Methyl orange turns yellow. Methyl red turns yellow. Bromothymol blue turns green,What is the estimated pH of the solution?4.3 7.32.85.3

Answer 1

Acid and bases - Indicators

And acid-base indicator is a substance that displays displays different colors when in the presence of an acid or a base.

Answer:

In order to answer we have to see the results for each indicator.

1. For Thymol blue: turns yellow, so we know the pH of the solution must be between 2,8 and 8.

2. For Methyl orange: turns yellow, so we know it must be between 4.6 and 8 (according to the previuos result).

3. For Methyl red: turns yellow, so it must be between 6.3 and 8 (according to the previous results)

4. For Bromothymol blue: turns green, so it must be between 6.3 and 7.8 (according to the previous results).

As we can see the only pH that matches the result is 7.3, 1.