sufur Oxides

There are many different stable sulfur oxides, but the two that are commonly found are sulfur dioxide and sulfur trioxide. Sulfur dioxide is a commonly found oxide of sulfur. It is a colorless, pungent, and nonflammable gas. It has a density of 2.8 kg/m³ and a melting point of -72.5 ^oC. Because organic materials are more soluble in SO2 than in water, the liquid form is a good solvent. SO2 is primarily used to produce SO3. The direct combustion of sulfur and the roasting of metal sulfides yield SO2 via the contact process:

Sulfur trioxide is another one of the commonly found oxides of sulfur. It is a colorless liquid with a melting point of 16.9 ^oC and a density of kg/m³. SO3

is used to produce sulfuric acid. SO2 is used in the synthesis of SO3:

This reaction needs a catalyst to be completed in a reasonable amount of time with V2O5 is the catalyst most commonly used.