Chapter 19.2, Problem 17PP

Interpretation Introduction

Interpretation:

The given redox reaction is to be balanced using oxidation number method.

Concept introduction:

Oxidation number method 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.
• Then balance the other elements.

Answer to Problem 17PP

$8N{H}_3+6N{O}_2\to 7N_2+12H_{2}O$

Explanation of Solution

The given redox reaction is:

$N{H}_3+N{O}_2\to N_2+H_{2}O$

Assigning the oxidation number-

$\stackrel{-3}{N}{\stackrel{+1}{H}}_3+\stackrel{+4}{N}{\stackrel{-2}{O}}_2\to {\stackrel{0}{N}}_2+{\stackrel{+1}{H}}_2\stackrel{-2}{O}$

The oxidation numbers of atoms shows that

$NofN{H}_3$ is oxidized and $NofN{O}_2$ is reduced.

Change in oxidation number of $N=+3$

Change in oxidation number of $N=-4$

Thus adjusting the coefficients:

$4N{H}_3+3N{O}_2\to N_2+H_{2}O$

After readjustment:

$8N{H}_3+6N{O}_2\to 7N_2+12H_{2}O$

Conclusion

Thus the balanced redox equation is:

$8N{H}_3+6N{O}_2\to 7N_2+12H_{2}O$