Is SO2 Polar or Nonpolar?

Answer: SO2 is a polar molecule because the lone pair of electrons on the central sulfur atom cause electron-electron repulsion that forces a bent structure leading to an unequal distribution of charge throughout the molecule. 

Due to the molecules relatively strong dipole, the compound a melting point of -72˚C and a boiling point of -10˚C. This means that SO2 is a gas at standard temperature and pressure. The gas is found at low concentrations in earths atmosphere at less than 1 ppm. It features more prominently on the atmospheres of other plants. For example, Venus has an atmospheric concentration of 150 ppm SO2. It can be produced from constituent elements or sulfites. The molecule is said to have a pungent smell- similar to a just-struck match. 


SO2 Ball and Stick
SO2 Ball and Stick Diagram (one of two resonance structures). Made with Avagadro.
How is SO2 utilized in the real world?

Sulfur dioxide is most commonly utilized as an intermediate in the production of sulfuric acid. It can be used as a preservative for dried fruits and it has played an important role ini wine-making for millennia. On a chemical note it serves as an excellent reducing agent in many reactions and biochemical systems. At lower temperatures it is also utilized as a solvent. It is a major air pollutant.

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