Chapter 19, Problem 82A

Interpretation Introduction

(a)

Interpretation:

The given redox reaction is to be balanced.

Concept introduction:

Oxidation number method to balance ionic equation involve:-

• Assign the oxidation number to each element.
• Check which element is oxidized and which element is reduced.
• Check the change in oxidation number for the elements which are oxidized and reduced.
• Balance the change in oxidation number by adjusting the coefficients in the equation.

Answer to Problem 82A

$3P+2H_{2}O+5HN{O}_3\to 3H_{3}P{O}_4+5NO$

Explanation of Solution

The given redox reaction is:

$P+H_{2}O+HN{O}_3\to H_{3}P{O}_4+NO$

Assigning the oxidation number-

$\stackrel{0}{P}+H_{2}O+H\stackrel{+5}{N}{O}_3\to H_3\stackrel{+5}{P}{O}_4+\stackrel{+2}{N}O$

The oxidation numbers of atoms shows that

$P$ is oxidized and $N$ is reduced.

Change in oxidation number of $P=+5$

Change in oxidation number of $N=-3$

Thus adjusting the coefficients:

$3P+H_{2}O+5HN{O}_3\to 3H_{3}P{O}_4+5NO$

Adjusting the rest atoms:

$3P+2H_{2}O+5HN{O}_3\to 3H_{3}P{O}_4+5NO$

Interpretation Introduction

(b)

Interpretation:

The given redox reaction is to be balanced.

Concept introduction:

Oxidation number method to balance ionic equation involve:-

• Assign the oxidation number to each element.
• Check which element is oxidized and which element is reduced.
• Check the change in oxidation number for the elements which are oxidized and reduced.
• Balance the change in oxidation number by adjusting the coefficients in the equation.

Answer to Problem 82A

$2KCl{O}_3+4HCl\to C{l}_2+2Cl{O}_2+2H_{2}O+2KCl$

Explanation of Solution

The given redox reaction is:

$KCl{O}_3+HCl\to C{l}_2+Cl{O}_2+H_{2}O+KCl$

Assigning the oxidation number-

$K\stackrel{+5}{Cl}{O}_3+H\stackrel{-1}{Cl}\to \stackrel{0}{C{l}_2}+\stackrel{+4}{Cl}{O}_2+H_{2}O+K\stackrel{-1}{Cl}$

The oxidation numbers of atoms shows that

$Cl$ is oxidized and $Cl$ is reduced.

Change in oxidation number of $Cl=5+1+6=12$

Change in oxidation number of $Cl=-1-5=-6$

Thus adjusting the coefficients:

$KCl{O}_3+2HCl\to \frac{1}{2}C{l}_2+Cl{O}_2+H_{2}O+KCl$

Adjusting the rest atoms:

$2KCl{O}_3+4HCl\to C{l}_2+2Cl{O}_2+2H_{2}O+2KCl$