Chemistry in the Environment: Acid Rain

• Acid rain occurs when rainwater mixes with air pollutants—such as NO, NO2, and SO2—that form acids.
• NO and NO2, primarily from vehicular emission, combine with water to form HNO3(aq).
• SO2, primarily from coal-powered electricity generation, combines with water and oxygen in air to form H2SO4(aq).
• HNO3(aq) and H2SO4(aq) both cause rainwater to become acidic.
• When acid rain flows into lakes and streams, some species of aquatic animals cannot tolerate the increased acidity and die.
• Acid rain weakens trees by dissolving nutrients in the soil and by damaging their leaves.
• Acid rain also damages building materials.