Final answer:
Sulfur dioxide and nitrogen oxides react with water in the atmosphere to create sulfuric and nitric acids, resulting in acid rain. These reactions also contribute to the formation of smog, especially photochemical smog from car emissions.
Step-by-step explanation:
When sulfur dioxide (SO2) and nitrogen oxides combine with water in the atmosphere, they undergo chemical reactions to form sulfuric acid (H2SO4) and nitric acid (HNO3). This process occurs when emissions from power plants, automobiles, and industrial activities release these gases into the atmosphere, where they can be carried over long distances by prevailing winds. When these acidic compounds fall back to earth with precipitation, they create acid rain, which has a pH lower than 5.
Sulfur dioxide reacts with water to form sulfurous acid (H2SO3), which can further react to form sulfuric acid. At the same time, nitrogen dioxide (NO2) reacts with water to produce a combination of nitrous acid (HNO2) and nitric acid (HNO3). These reactions are harmful to the environment, contributing to the formation of acid rain, which can cause widespread damage to ecosystems, buildings, and even human health due to the creation of fine particulate matter.
The formation of smog is also related to nitrogen oxides and occurs when these gases are emitted, particularly from car engines, and undergo chemical reactions in the presence of sunlight to produce a mixture of air pollutants, including ozone. This type of smog is known as photochemical smog and has serious health implications.