Question

Nitric acid is a component of acid rain that forms when gaseous nitrogen dioxide pollutant reacts with gaseous oxygen and liquid water to form aqueous nitric acid.

Answer 1

Initial formation of nitric acid
\[2NO_2 + H_2O \rightarrow HNO_2 + HNO_3\]

Decomposition of nitrous acid
\[3HNO_3 \rightarrow HNO_3 + 2 NO + H_2O\]

Nitric oxide also reacts in atmosphere
\[4NO + 3O_2 + 2H_2O \rightarrow 4HNO_3\]


You can balance these to get an overall reaction of;
\[2NO + 2NO_2 + 2HNO_2 + 2H_2O + 3O_2 \rightarrow 6HNO_3 \]