1(x)
Assertion (A): In the Contact Process SO3 gas is not directly dissolved in water to obtain sulphuric acid.
Reason (R): Dense fog or misty droplets of sulphuric acid are formed which is difficult to condense.
- (a)Both (A) and (R) are true, and (R) is the correct explanation of (A).
- (b)Both (A) and (R) are true, and (R) is not the correct explanation of (A).
- (c)(A) is true but (R) is false.
- (d)(A) is false but (R) is true.
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Both (A) and (R) are true, and (R) is the correct explanation of (A).
Reason — When sulphur trioxide is brought into direct contact with water,
SO3(g) + H2O(l) ⟶ H2SO4(l)
the reaction is highly exothermic. The heat released vaporises some of the acid and produces a dense fog of minute H2SO4 droplets, which are difficult to condense and collect. Therefore, in the Contact Process the SO3 is first absorbed in concentrated sulphuric acid to form oleum, which is later diluted with water to give the required concentration of H2SO4.