Chapter 13, Problem 29QP

(a)

Interpretation Introduction

Interpretation:

Whether ${\text{H}}_2{\text{SO}}_4\left(aq\right)$ is a strong acid, weak acid, strong base or a weak base is to be identified and an equation that describes its reaction with water is to be written.

Explanation of Solution

From the table $13.1$ (from the book), ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ is a strong acid. ${\text{H}}_2{\text{SO}}_4\left(aq\right)$ dissociates completely into $\left({\text{H}}_3{\text{O}}^{+}\right)$ and $\left({\text{HSO}}_4^{-}\right)$ ions in the aqueous solution. Due to this, the aqueous solution becomes more acidic. Hence, ${\text{H}}_2{\text{SO}}_4$ is a strong acid. The reaction of ${\text{H}}_2{\text{SO}}_4$ with water is shown below.

${\text{H}}_2{\text{SO}}_4\left(aq\right)+{\text{H}}_2\text{O}\left(l\right)\to {\text{H}}_3{\text{O}}^{+}\left(aq\right)+{\text{HSO}}_4^{-}\left(aq\right)$

(b)

Interpretation Introduction

Interpretation:

Whether $\text{Ca}{\left(\text{OH}\right)}_2\left(aq\right)$ is a strong acid, weak acid, strong base or a weak base is to be identified and an equation that describes its reaction with water is to be written.

Explanation of Solution

According to table $13.2$ (from the book), $\text{Ca}{\left(\text{OH}\right)}_2$ is a strong base. $\text{Ca}{\left(\text{OH}\right)}_2\left(aq\right)$ is ionic. It ionizes completely into calcium ions $\left({\text{Ca}}^{2+}\right)$ and hydroxide ions $\left({\text{OH}}^{-}\right)$ , which indicates that it is a strong base. The ionization of calcium hydroxide in water is given as shown below.

$\text{Ca}{\left(\text{OH}\right)}_2\left(aq\right)\to {\text{Ca}}^{2+}\left(aq\right)+2{\text{OH}}^{-}\left(aq\right)$

(c)

Interpretation Introduction

Interpretation:

Whether ${\text{Na}}_2{\text{CO}}_3\left(aq\right)$ is a strong acid, strong base, weak acid or a weak base is to be identified and an equation that describes its reaction with water is to be written.

Explanation of Solution

The conjugate base of a weak acid is strong. Since ${\text{Na}}_{\text{2}}{\text{CO}}_3$ is a salt of a weak acid and a strong base, ${\text{Na}}_{\text{2}}{\text{CO}}_3$ is a strong base. The reaction of ${\text{Na}}_{\text{2}}{\text{CO}}_3$ with water results in the formation of sodium hydroxide and water. The reaction is given as shown below.

${\text{Na}}_{\text{2}}{\text{CO}}_{\text{3}}\to 2\text{NaOH}+{\text{CO}}_2$

(d)

Interpretation Introduction

Interpretation:

Whether ${\text{H}}_3{\text{C}}_6{\text{H}}_5{\text{O}}_7\left(aq\right)$ is a strong acid, weak acid, strong base or a weak base is to be identified and an equation that describes its reaction with water is to be written.

Explanation of Solution

The formula $\left({\text{H}}_3{\text{C}}_6{\text{H}}_5{\text{O}}_7\right)$ is the salt of citric acid. Since citric acid is a weak acid, the conjugate base of a weak acid is strong. Therefore, $\left({\text{H}}_3{\text{C}}_6{\text{H}}_5{\text{O}}_7\right)$ is a strong base. The reaction of ${\text{H}}_3{\text{C}}_6{\text{H}}_5{\text{O}}_7\left(aq\right)$ with water is given as shown below.

${\text{H}}_3{\text{C}}_6{\text{H}}_5{\text{O}}_7\left(aq\right)+{\text{H}}_2\text{O}\left(l\right)\rightleftharpoons {\text{H}}_3{\text{O}}^{+}\left(aq\right)+{\text{H}}_2{\text{C}}_6{\text{H}}_5{\text{O}}_7^{-}\left(aq\right)$

(e)

Interpretation Introduction

Interpretation:

Whether ${\text{C}}_6{\text{H}}_5{\text{NH}}_2\left(aq\right)$ is a strong acid, weak acid, strong base or a weak base and an equation that describes its reaction with water is to be written.

Explanation of Solution

${\text{C}}_6{\text{H}}_5{\text{NH}}_2\left(aq\right)$ dissociates partially in water and hence, is a weak base. The reaction of ${\text{C}}_6{\text{H}}_5{\text{NH}}_2$ with water is given below.

${\text{C}}_6{\text{H}}_5{\text{NH}}_2\left(aq\right)+{\text{H}}_2\text{O}\left(l\right)\to {\text{C}}_6{\text{H}}_5{\text{NH}}_3^{+}\left(aq\right)+{\text{OH}}^{-}\left(aq\right)$