Question

To produce sulphuric acid by contact process they use h2so4 instead of water why?

Answer 1

The 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 pyrosulphuric acid or oleum.