LAQ : Write the principle of the manufacture of H2SO4

Question

Write the principle of the manufacture of H₂SO₄. 

Answer

The principle of the manufacture of H₂SO₄ by the Contact Process involves the following steps:

1. Preparation of sulfur dioxide (SO₂) by burning sulfur or by roasting metal sulfides.
   S + O₂ = SO₂ (4FeS₂ + 11O₂ = 2Fe₂O₃ + 8SO₂)
2. Conversion of SO₂ to sulfur trioxide (SO₃) by catalytic oxidation with oxygen using a vanadium pentoxide catalyst at a temperature of around 450-500°C.
   2SO₂ + O₂ = 2SO₃ + Heat
3. Absorption of SO₃ in 98% sulfuric acid to produce oleum (a mixture of H₂SO₄ and SO₃).
   H₂SO₄ + SO₃ = H₂S₂O₇
4. Dilution of oleum with water to obtain the desired concentration of sulfuric acid (typically 98% or 96%).
   H₂S₂O₇ + H₂O = 2H₂SO₄
5. Recycling of unreacted SO₂ and excess oxygen to the oxidation step.