Explain why CO2 is non polar molecule whereas SO2 is polar molecule
The Correct Answer and Explanation is:
Correct Answer:
Carbon dioxide (CO₂) is a non-polar molecule, while sulfur dioxide (SO₂) is a polar molecule because of differences in their molecular geometry and symmetry, even though both contain polar bonds.
Detailed Explanation
The polarity of a molecule depends on two main factors. These are the polarity of the individual bonds and the shape or geometry of the molecule which determines whether the bond dipoles cancel each other.
In the case of carbon dioxide (CO₂), the molecule has a linear shape with an angle of 180 degrees between the oxygen atoms. Each carbon-oxygen bond is polar because oxygen is more electronegative than carbon. However, the two bond dipoles point in exactly opposite directions and have equal magnitude. As a result, they cancel each other out completely, making the overall molecule non-polar despite having polar bonds.
In contrast, sulfur dioxide (SO₂) has a bent or V-shaped molecular geometry with a bond angle of approximately 119 degrees due to the presence of a lone pair of electrons on the sulfur atom. Like in CO₂, each sulfur-oxygen bond in SO₂ is polar because of the difference in electronegativity between sulfur and oxygen. However, because the molecule is bent, the bond dipoles do not oppose each other directly. Instead, they combine to create a net dipole moment pointing in a specific direction, which results in the whole molecule being polar.
Therefore, the key reason CO₂ is non-polar is because its linear structure allows for complete cancellation of the bond dipoles. On the other hand, SO₂ has a bent structure that prevents such cancellation, giving the molecule an overall polarity.
This difference is significant in determining their physical and chemical properties. For example, polar molecules like SO₂ dissolve well in polar solvents and interact strongly through dipole forces, while non-polar molecules like CO₂ dissolve better in non-polar environments.
