Chapter 19, Problem 99A

Interpretation Introduction

Interpretation : The accuracy of the statement is to be evaluated.

Concept Introduction : An indicator is a chemical substance that changes color when an acid or base is present.

Answer to Problem 99A

The statement is not accurate since indicator changes its color according to the pH.

Explanation of Solution

An indicator is a chemical substance that changes color when an acid or base is present.

The titration's end point occurs when the indicator's color changes.

The indicator changes its color depending on the pH of the solution.

They are not precise since they keep changing according to the pH.

Methyl red changes color when exposed to acid.

Interpretation Introduction

Interpretation : The accuracy of the statement is to be evaluated.

Concept Introduction : Acids are used to produce hydrogen ions by ionization. Bases are used to produce hydroxide ions by ionization.

Answer to Problem 99A

The statement is not accurate since ammonia is a base according to Bronsted Lowry’s theory.

Explanation of Solution

Acids, according to Arrhenius, are substances that contain hydrogen and ionize to produce hydrogen ions $\left({\text{H}}^{\text{+}}\right)$ in an aqueous solution.

Bases are substances that ionize in aqueous solutions to produce hydroxide ions $\left({\text{OH}}^{-}\right)$ .

The statement is not accurate.

Ammonia is not a base according to Arrhenius’s definition as it does not dissociate to give hydroxide ions.

Ammonia is a base according to Bronsted Lowry’s theory.

Interpretation Introduction

Interpretation : The accuracy of the statement is to be evaluated.

Concept Introduction : Acids are used to produce hydrogen ions by ionization. Bases are used to produce hydroxide ions by ionization.

Answer to Problem 99A

The statement is not accurate since concentration and strength are two different terms.

Explanation of Solution

The strength of the solution deals with the dissociative nature of the acid or base in the solution.

The concentration of the solution deals with the amount of acid or base present.

The strength is entirely different from the concentration of the solution.

So, they are not related to each other.

The statement is not accurate.