Question

In contact process, sulphur trioxide formed is dissolved in 98% sulphuric acid and not in water.

• A. True
• B. False

Answer 1

The correct option is A

True

Sulphur trioxide formed is not dissolved in water directly as the reaction is highly exothermic and would form clouds of sulphur trioxide and water vapour. These would corrode the plant and machinery. Sulphur trioxide is absorbed by 98% sulphuric acid to produce oleum (pyrosulphuric acid).

$S{O}_3+H_{2}S{O}_4\to H_2{S}_2{O}_7$