When rain is accompanied by a thunder storm, the collected rain water will have a pH value — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

During a thunderstorm, high-temperature electrical discharges cause atmospheric nitrogen ($N_2$) and oxygen ($O_2$) to react and form nitric oxide ($NO$). This is oxidized to nitrogen dioxide ($NO_2$), which dissolves in rain water to form nitrous acid (HNO2) and nitric acid ($HNO_3$). The presence of these acids increases the hydronium ion concentration [H3O+], thereby lowering the pH compared to normal rain water.