Acid rain is primarily caused by the emission of sulfur dioxide SO2 and nitrogen oxides NOx into the atmosphere. These gases are released from various sources, such as burning fossil fuels, industrial processes, and vehicle emissions. Once in the atmosphere, SO2 and NOx undergo a series of chemical reactions with water, oxygen, and other compounds to form sulfuric acid H2SO4 and nitric acid HNO3 , which then fall to the ground as acid rain.The main chemical reactions contributing to the formation of acid rain are:1. Oxidation of sulfur dioxide SO2 to form sulfur trioxide SO3 : 2SO2 + O2 2SO32. Formation of sulfuric acid H2SO4 from sulfur trioxide SO3 and water H2O : SO3 + H2O H2SO43. Oxidation of nitrogen monoxide NO to form nitrogen dioxide NO2 : 2NO + O2 2NO24. Formation of nitric acid HNO3 from nitrogen dioxide NO2 and water H2O : 2NO2 + H2O HNO3 + HNO25. Further oxidation of nitrous acid HNO2 to form nitric acid HNO3 : 2HNO2 + O2 2HNO3When acid rain falls on the ground, it can have several negative effects on soil pH and water quality in affected areas:1. Lowering soil pH: Acid rain increases the acidity of the soil, which can lead to a decrease in soil pH. This can harm plants and other organisms that are sensitive to changes in pH, as well as affect the availability of essential nutrients in the soil.2. Leaching of nutrients: Acid rain can cause essential nutrients, such as calcium, magnesium, and potassium, to be leached from the soil. This can lead to nutrient deficiencies in plants and reduced agricultural productivity.3. Mobilization of toxic metals: Acid rain can cause toxic metals, such as aluminum, to be mobilized from soil particles and enter the soil solution. These toxic metals can be taken up by plants, potentially harming their growth and making them toxic to animals that consume them.4. Acidification of water bodies: Acid rain can cause the pH of lakes, rivers, and streams to decrease, leading to the acidification of these water bodies. This can harm aquatic life, particularly fish and other organisms that are sensitive to changes in pH.5. Eutrophication: The increased presence of nitrates from nitric acid in acid rain can contribute to eutrophication, a process where excessive nutrients in water bodies lead to algal blooms and oxygen depletion. This can have severe consequences for aquatic ecosystems, including fish kills and loss of biodiversity.In summary, the chemical reactions that contribute to the formation of acid rain involve the oxidation of sulfur dioxide and nitrogen oxides to form sulfuric acid and nitric acid. These acids can negatively impact soil pH, water quality, and overall ecosystem health in affected areas.