What is a key chemical reaction that leads to acid rain?

The formation of acid rain is primarily driven by the chemical reactions that occur when sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) are released into the atmosphere, often from the burning of fossil fuels. These compounds can react with water vapor, oxygen, and other chemicals present in the atmosphere. Specifically, sulfur dioxide can react with water to form sulfurous acid (H₂SO₃), which can further oxidize to sulfuric acid (H₂SO₄). Similarly, nitrogen oxides can react with water to form nitric acid (HNO₃).

These resulting acids are then deposited back to Earth as acid rain, which can have harmful effects on aquatic ecosystems, soil, and infrastructure. The process highlights the significant impact of human activities on natural systems and demonstrates the importance of controlling emissions to mitigate environmental damage.