In the Contact Process for manufacturing sulphuric acid, Sulphur trioxide (SO3) is not absorbed in water because:

Explanation

In the Contact Process, sulphur trioxide (SO3) is produced by the oxidation of sulphur dioxide (SO2) in the presence of a vanadium(V) oxide catalyst. The reaction is highly exothermic and produces a lot of heat. This means that if SO3 were to come into contact with water, it would react vigorously with it, releasing a large amount of heat and forming sulphuric acid (H2SO4) through the following reaction:SO3(g) + H2O(l) → H2SO4(l) (exothermic)This reaction is highly exothermic and can cause the mixture to boil and even explode due to the sudden release ofheat. Therefore, in the Contact Process, SO3 is not allowed to come into contact with water and is instead absorbed in concentrated sulphuric acid to form oleum, which can be further diluted with water to produce sulphuric acid.