Divanadium trioxide

Divanadium trioxide combusts spontaneously in air. For some authors this behaviour is observed at ambient temperature, for others, heating is necessary. 

Divanadium trioxide is entirely basic and dissolves in acids to give solutions of the V111 aqua ion or its complexes. From these solutions addition of OH- gives the hydrous oxide, which is very easily oxidized in air. 

The catalyst used is divanadium pentoxide, V2C>5, at a temperature of450°C to 600°C. Sulfur trioxide is an acidic oxide that reacts with water to form sulfuric acid. 

Li03Re, Lithium rhenium trioxide, 24 205 LiOsV2, Lithium divanadium pentaoxide, 24 202... 

The equilibrium constant for this reaction is 1.7 X 10 , which indicates that for all practical purposes the reaction should go almost completely to products. Yet when sulfur is burned in air or oxygen, it forms predominantly SO2 and very little SO3. Oxidation of SO2 to SO3 is simply too slow to give a significant amount of product. However, the rate of the reaction is appreciable in the presence of a platinum or divanadium pentoxide catalyst. The oxidation of SO2 in the presence of a catalyst is the main step in the contact process for the industrial production of sulfuric acid, H2SO4. Sulfur trioxide reacts with water to form sulfuric acid. (In the industrial process, SO3 is dissolved in concentrated H2SO4, which is then diluted.) ... 

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