Acid Rain
Definition and meaning of Acid Rain in chemistry.
Acid rain is precipitation that is significantly more acidic than normal rainwater, containing sulfuric acid (H2SO4) and nitric acid (HNO3) formed from dissolved sulfur dioxide and nitrogen oxides. These pollutants originate from fossil fuel combustion in power plants and vehicles.
In more detail
When sulfur dioxide and nitrogen oxides are released into the atmosphere, they react with water vapor to form sulfuric acid (H2SO4) and nitric acid (HNO3). Normal rainwater is naturally slightly acidic (pH ~5.6) due to dissolved carbon dioxide, but acid rain typically has a pH between 3.0 and 5.0. This increased acidity causes significant environmental damage to ecosystems, corrodes buildings and infrastructure, and depletes soil nutrients by leaching essential minerals. The phenomenon became widely recognized during the 1970s–1980s, particularly affecting forests and freshwater lakes in industrialized regions.
Key facts
| Field | General Chemistry |
|---|---|
| Typical pH range | 3.0–5.0 (normal rain is ~5.6) |
| Primary acidic compounds | H2SO4 and HNO3 |
| Main emission sources | Fossil fuel combustion, industrial processes |
In the northeastern United States during the 1980s, acid rain with pH values between 4.0 and 4.5 regularly fell on the Adirondack Mountains, significantly damaging forest ecosystems and acidifying lakes to the point that fish populations could not survive.
Frequently asked questions
What causes acid rain?
Acid rain forms when sulfur dioxide (SO2) and nitrogen oxides (NOₓ) from burning fossil fuels and industrial processes dissolve in atmospheric water vapor to form sulfuric and nitric acid.
How does acid rain harm the environment?
Acid rain damages forest soils by leaching nutrients, acidifies lakes and streams causing aquatic life to die, corrodes buildings and monuments, and reduces crop yields in agricultural areas.