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💏intro to chemistry review

Sulfur Dioxide

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Sulfur dioxide (SO2) is a colorless, pungent gas that is formed by the combustion of fossil fuels containing sulfur. It is a major air pollutant that can have significant impacts on the environment and human health when present in high concentrations.

5 Must Know Facts For Your Next Test

  1. Sulfur dioxide is produced primarily from the combustion of fossil fuels, such as coal and oil, in power plants, factories, and vehicles.
  2. Exposure to high levels of sulfur dioxide can cause respiratory problems, particularly in individuals with pre-existing lung conditions like asthma.
  3. Sulfur dioxide can undergo further oxidation in the atmosphere to form sulfate particles, which contribute to the formation of particulate matter (PM) pollution.
  4. Sulfur dioxide can dissolve in water to form sulfurous acid (H2SO3), which is the primary cause of acid rain and its associated environmental effects.
  5. The hybridization of sulfur dioxide's central sulfur atom is $\text{sp}^3$, resulting in a bent molecular geometry with a bond angle of approximately 120 degrees.

Review Questions

  • Explain the role of hybrid atomic orbitals in the structure and bonding of sulfur dioxide (SO2) molecules.
    • The central sulfur atom in the sulfur dioxide (SO2) molecule undergoes $\text{sp}^3$ hybridization, forming four hybrid orbitals. Two of these hybrid orbitals are used to form the double bonds with the oxygen atoms, while the remaining two hybrid orbitals accommodate the lone pairs of electrons on the sulfur atom. This hybridization pattern results in a bent molecular geometry with a bond angle of approximately 120 degrees, which is a characteristic feature of the sulfur dioxide molecule.
  • Describe the oxidation-reduction reactions involving sulfur dioxide and how they contribute to environmental issues such as acid rain.
    • Sulfur dioxide can participate in various oxidation-reduction (redox) reactions in the atmosphere. When sulfur dioxide reacts with oxygen, it can be further oxidized to form sulfur trioxide (SO3), which then reacts with water to produce sulfuric acid (H2SO4). This sulfuric acid can dissolve in atmospheric water droplets, leading to the formation of acid rain. Acid rain can have detrimental effects on ecosystems, including the acidification of lakes and streams, damage to vegetation, and the corrosion of buildings and infrastructure.
  • Analyze the potential environmental and health impacts of high concentrations of sulfur dioxide in the atmosphere, and discuss strategies for mitigating these issues.
    • Elevated levels of sulfur dioxide in the atmosphere can have significant environmental and health consequences. Environmentally, sulfur dioxide can contribute to the formation of particulate matter (PM) pollution, which can reduce visibility and have adverse effects on ecosystems. Additionally, the conversion of sulfur dioxide to sulfuric acid leads to acid rain, which can damage vegetation, contaminate water sources, and corrode infrastructure. From a health perspective, exposure to high concentrations of sulfur dioxide can cause respiratory problems, particularly in individuals with pre-existing lung conditions like asthma. To mitigate these issues, strategies such as the use of cleaner energy sources, the implementation of emission control technologies, and the development of more efficient industrial processes can help reduce the release of sulfur dioxide into the atmosphere.