Question

Balance the following equations by oxidation number method.
$HgS+HI+HN{O}_3\to H_{2}Hg{I}_4+NO+S+H_{2}O$

Answer 1

Rules for balancing a chemical equation [oxidation number method] :-

1. Write an unbalanced equation.

2. Assign oxidation number for each atom.

3. Identify redox reactions and write separately as half reactions.

4. Balance all other atoms except $H$ and $O$ in each half reaction.

5. Balance the hydrogen by $H^{+}$ or $O{H}^{-}$ .

6. Balance the oxygen atoms by adding $H_{2}O$.

7. Make electron gain equivalent to electron loss in the half reactions by multiplying them with the respective numbers.

8. Add and simplify the half reactions together.

9. Check that the elements and charges are balanced.

We get,

$3HgS+12HI+2HN{O}_3⟶3H_{2}Hg{I}_4+2NO+3S+4H_{2}O$ .