Explain the chemistry principle for acid rain
The correct answer and explanation is:
Correct Answer:
The chemistry principle behind acid rain involves the reaction of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) with water, oxygen, and other chemicals in the atmosphere to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃), which then fall to the ground in precipitation.
Explanation:
Acid rain is the result of chemical reactions that occur when sulfur dioxide and nitrogen oxides are released into the atmosphere. These gases primarily come from burning fossil fuels such as coal, oil, and gas in power plants, factories, and vehicles. Once released, sulfur dioxide and nitrogen oxides rise into the atmosphere, where they interact with water vapor, oxygen, and other atmospheric chemicals.
The key chemical reactions begin when sulfur dioxide reacts with water and oxygen to form sulfurous acid (H₂SO₃) and then further oxidizes to become sulfuric acid (H₂SO₄). Similarly, nitrogen oxides react with water to form nitric acid (HNO₃). These acids dissolve in cloud water and result in acidic precipitation. The main reactions can be summarized as follows:
- SO₂ + H₂O → H₂SO₃
- 2SO₂ + O₂ → 2SO₃
- SO₃ + H₂O → H₂SO₄
- 2NO₂ + H₂O → HNO₃ + HNO₂
The acids formed lower the pH of rainwater. Normal rainwater has a slightly acidic pH of about 5.6 due to dissolved carbon dioxide forming carbonic acid. Acid rain has a pH lower than this, often around 4.0 or even lower.
These chemical reactions illustrate how pollution from human activities directly alters atmospheric chemistry. Once acid rain falls to Earth, it can cause damage to soils, water bodies, plants, buildings, and even human health. Understanding these reactions is essential to managing emissions and reducing environmental harm.