Question

The indicator chlorophenol red is yellow below pH 5.2 and red above pH 6.8. When a drop of chlorophenol red is added to a solution of 0.12 M HClO4, what color will it turn?

Answer 1

The indicator chlorophenol red is yellow below pH 5.2 and red above pH 6.8. When a drop of chlorophenol red is added to a solution of 0.12 M HClO4, what color will it turn

First we calculate the pH of the as follows:

HClO4 -----> H+ + ClO4-

HClO4 is a very strong acid and dissociates or ionizes 100%.
thus 0.12 M HClO4 gives 0.12 M H+

And pH = -log [H+]

pH = -log (0.12) = 0.921

Given that The indicator chlorophenol red is yellow below pH 5.2 and red above pH 6.8. here the pH of the solution is 0.921 which is below pH 5.2 thus the color is yellow of solution