Chapter 9, Problem 9.5P

Interpretation Introduction

Interpretation:

Reason for indicator cresol red to change its color with change in $\text{pH}$ value has to be explained. Also, color at $\text{pH}$ 10, 8 and 6 of cresol red has to be given.

Concept Introduction:

Acid-base indicators are those that show property of both acid and base as their protonated forms have different colors at different $\text{pH}$. Indicators are generally used in titrimetric analysis. Cresol red has two transition $\text{pH}$ ranges that are $0.2-1.8$ and $7.2-8.8$. In acid, its color changes to red, and in base color becomes yellow in range $0.2-1.8$. For range from $7.2-8.8$ in acid, its color changes to yellow and in base color becomes red.