SO2

Definition

Sulfur dioxide (SO2) is a colorless, toxic gas with a pungent odor. It is a major air pollutant that is produced from the combustion of fossil fuels containing sulfur, such as coal and oil. SO2 is an important chemical species that is closely tied to the concepts of molecular structure and polarity.

5 Must Know Facts For Your Next Test

1. The sulfur atom in SO2 has an oxidation state of +4, and the molecule has a bent, trigonal planar molecular geometry.
2. The oxygen atoms in SO2 are more electronegative than the sulfur atom, resulting in a polar covalent bond and a net dipole moment.
3. The presence of two lone pairs of electrons on the sulfur atom contributes to the bent shape of the SO2 molecule, as predicted by VSEPR theory.
4. SO2 is a major contributor to acid rain, as it can react with water in the atmosphere to form sulfuric acid (H2SO4).
5. Exposure to high levels of SO2 can be harmful to human health, causing respiratory issues and aggravating conditions like asthma.

Review Questions

• Explain the molecular geometry of the SO2 molecule and how it is determined by the VSEPR theory.
  • The SO2 molecule has a bent, trigonal planar molecular geometry. This is because the sulfur atom has four electron pairs in its valence shell: two bonding pairs with the oxygen atoms and two lone pairs. According to the VSEPR theory, the arrangement of these electron pairs around the central sulfur atom results in a bent shape, with the bond angle between the oxygen atoms being less than 120 degrees. The presence of the two lone pairs on the sulfur atom contributes to the overall bent geometry of the molecule.
• Describe the polarity of the SO2 molecule and how it is related to the electronegativity difference between the sulfur and oxygen atoms.
  • The SO2 molecule is a polar molecule due to the difference in electronegativity between the sulfur and oxygen atoms. Oxygen is more electronegative than sulfur, meaning it has a greater ability to attract shared electrons in the covalent bonds. This unequal sharing of electrons results in a separation of charge, with the oxygen atoms bearing a partial negative charge and the sulfur atom bearing a partial positive charge. This charge separation creates a net dipole moment in the molecule, making SO2 a polar compound.
• Discuss the environmental and health implications of the chemical properties of SO2, specifically its role in acid rain formation and its impact on respiratory health.
  • The chemical properties of SO2 have significant environmental and health consequences. As a major air pollutant, SO2 can react with water in the atmosphere to form sulfuric acid, contributing to the formation of acid rain. Acid rain can have detrimental effects on ecosystems, damaging plants and aquatic life. Additionally, exposure to high levels of SO2 can be harmful to human health, particularly for individuals with respiratory conditions like asthma. SO2 can irritate the lungs and airways, exacerbating respiratory symptoms and potentially leading to more severe health problems. Understanding the molecular structure and polarity of SO2 is crucial in addressing these environmental and public health concerns.

Related terms

Molecular Geometry:

The three-dimensional arrangement of atoms in a molecule, which determines its overall shape and properties.

Dipole Moment:

A measure of the separation of positive and negative electrical charges within a molecule, which determines its polarity.

Valence Shell Electron Pair Repulsion (VSEPR) Theory:

A model used to predict the molecular geometry of a compound based on the number of bonding and non-bonding electron pairs surrounding the central atom.