Question

Balance the following equation.

$Zn+HN{O}_3\to 4Zn(N{O}_3{)}_2+N_{2}O+H_{2}O$

• A. $4Zn+10HN{O}_3\to 4Zn(N{O}_3{)}_2+N_{2}O+5H_{2}O$
• B. $4Zn+5HN{O}_3\to 4Zn(N{O}_3{)}_2+3N_{2}O+5H_{2}O$
• C. $4Zn+15HN{O}_3\to 4Zn(N{O}_3{)}_2+2N_{2}O+5H_{2}O$
• D. None of these

Answer 1

Answer: (A)

$4Zn+10HN{O}_3\to 4Zn(N{O}_3{)}_2+N_{2}O+5H_{2}O$

The unbalanced redox equation is as follows:

$Zn+HN{O}_3\to 4Zn(N{O}_3{)}_2+N_{2}O+H_{2}O$

Balance all atoms other than $H$ and $O.$

$4Zn+10HN{O}_3\to 4Zn(N{O}_3{)}_2+N_{2}O+H_{2}O$

The oxidation number of $Zn$ changes from 0 to +2. The change in the oxidation number of one $Zn$ atom is +2. For 4 $Zn$ atoms, the total change in the oxidation number is 8.

The oxidation number of N changes from +5 to +1. The change in the oxidation number of one N atom is 4. For 2 N atoms, the total change in the oxidation number is 8.

The increase in the oxidation number is balanced with a decrease in the oxidation number $O$ atoms are balanced adding 4 water molecules on RHS.

$4Zn+10HN{O}_3\to 4Zn(N{O}_3{)}_2+N_{2}O+5H_{2}O$

Hydrogen atoms are balanced.

This is the balanced chemical equation.