Final answer:
Acid rain is caused by sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions that react with water and other substances in the atmosphere, producing sulfuric acid and nitric acid, leading to rain with a pH lower than 5.
Step-by-step explanation:
Acid Rain Formation and Chemical Formulas
Acid rain is formed when emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) from natural and man-made sources, such as volcanoes, decaying vegetation, fossil fuel combustion, and industrial processes, react in the atmosphere with water, oxygen, and other chemicals to produce sulfuric acid and nitric acid.
These reactions create a mixture of wet and dry deposition with higher concentrations of these acids than what is found normally in precipitation.
The chemical reactions that lead to the formation of acid rain can be summarized as follows:
Normal rainwater has a pH between 5 and 6 due to the presence of dissolved CO2, forming carbonic acid (H2CO3).
However, acid rain has a pH lower than 5 as a result of these acidic compounds, which are more prevalent because of human activity.