What is the chemical composition of acid rain?

Question

Josephine Allen · Accepted Answer

Sulfuric acid (#H_2SO_4#), nitric acid (#HNO_3#), and carbonic acid (#H_2CO_3#) are the major components of acid rain.

These chemicals are released into the atmosphere naturally however prior to industrialization and the advent of factories and reliance on hydrocarbons (coal, gasoline, crude oil, et cetera) acid rain was a rare event. In recent decades acid rain has become an increasingly common event.

Wikipedia has a good general summary of the movement of these chemicals:

Roman Acosta · Answer

undefined The chemical composition of acid rain primarily consists of sulfuric acid (H2SO4) and nitric acid (HNO3), which are formed when sulfur dioxide (SO2) and nitrogen oxides (NOx) emitted from burning fossil fuels react with water vapor in the atmosphere. Additionally, acid rain may contain other acidic compounds such as hydrochloric acid (HCl) and carbonic acid (H2CO3) derived from natural sources or industrial emissions.

Emilia Aguirre · Answer

undefined The chemical composition of acid rain primarily consists of sulfuric acid (H2SO4) and nitric acid (HNO3). These acids form when sulfur dioxide (SO2) and nitrogen oxides (NOx), primarily emitted from burning fossil fuels, react with water, oxygen, and other chemicals in the atmosphere.

Sulfur dioxide (SO2) is produced by the combustion of fossil fuels containing sulfur impurities, such as coal and oil. When released into the atmosphere, sulfur dioxide reacts with oxygen and water to form sulfuric acid (H2SO4):

$$ SO2 + O2 + H2O → H2SO4 $$

Similarly, nitrogen oxides (NOx), including nitric oxide (NO) and nitrogen dioxide (NO2), are produced during combustion processes, such as those in vehicles and power plants. In the atmosphere, nitrogen oxides react with oxygen and water to form nitric acid (HNO3):

$$ 2NO2 + H2O + 1/2O2 → 2HNO3 $$

These acids dissolve in atmospheric moisture, forming acidic solutions that fall to the Earth's surface as acid rain. In addition to sulfuric acid and nitric acid, acid rain may also contain other acidic compounds, such as hydrochloric acid (HCl) and carbonic acid (H2CO3), depending on the sources of pollution and atmospheric conditions. However, sulfuric acid and nitric acid are the primary contributors to the acidity of acid rain.