Question

Write the conditions to maximize the yield of H₂SO₄ by Contact process.

Answer 1

Manufacture of sulphuric acid by Contact process involves three steps.
1. Burning of ores to form SO₂
2. Conversion of SO₂ to SO₃ by the reaction of the former with O₂ (V₂O₅ is used in this process as a catalyst.)
3. Absorption of SO₃ in H₂SO₄ to give oleum (H₂S₂O7)
The key step in this process is the second step. In this step, two moles of gaseous reactants combine to give one mole of gaseous product. Also, this reaction is exothermic. Thus, in accordance with Le Chatelier’s principle, to obtain the maximum amount of SO₃ gas, temperature should be low and pressure should be high.