Chapter 22, Problem 101A

a.

Interpretation Introduction

Interpretation: To interpret the approximate pH of the solution.

Concept Introduction: In measuring the pH two factors play a crucial role that is as follows:

• pH meters
• Acid-base indicators

Answer to Problem 101A

The approximate pH of the solution is 7 i.e., the solution is neutral in nature.

Explanation of Solution

Acid-base indicators are important in determining the pH of the solution. The color change occurs as the acidic or basic form of the solution shows different colors. Some examples of acid-base indicators are methyl orange, methyl red, phenolphthalein, etc.

From the question, a colorless solution turns blue when tested with a bromothymol blue indicator while it remains colorless when tested with phenolphthalein.

Phenolphthalein indicators show a pink color change in solutions above pH 8 while it is colorless in an acidic medium and the bromothymol blue indicator shows a blue color change at pH ranging from 7-8.

Therefore, the approximate pH of the solution is 7 i.e., the solution is neutral in nature.

b.

Interpretation Introduction

Interpretation: To give a more accurate way of determining the pH of the solution.

Concept Introduction: In measuring the pH two factors play a crucial role that is as follows:

• pH meters
• Acid-base indicators

Answer to Problem 101A

The more accurate way of determining pH is a pH meter.

Explanation of Solution

pH meter is a more accurate way of determining the pH of the solution. It is used to make rapid as well continuous measurements of pH. It is far better to use in comparison to liquid indicators as well as pH strips. It is also easy to use in laboratories as well as industries.