Question

Write balanced equations for the three chemical reactions that take place during the conversion of sulphur dioxide to sulphuric acid in the contact process. Name the catalyst used in the contact process.

Answer 1

Conversion of sulphur dioxide to sulphuric acid occurs according to the following steps:

1. Catalytic oxidation of sulphur dioxide: ${\text{2SO}}_2+{\text{O}}_2\underset{{\text{2 atm, 450-500}}^{0}C}{\overset{{\text{V}}_2{O}_5}{\to }}{\text{2SO}}_3\text{+ Heat}$

2. Formation of oleum (H₂S₂O₇ ): SO₃ + H₂SO₄ → H₂S₂O₇

3. Dilution of oleum: H₂S₂O₇ + H₂O → 2H₂SO₄

Platinum or vanadium pentaoxide is commonly used as the catalyst in the contact process.