Question

Describe the manufacture of H₂SO₄ by contact process?

Answer 1

Sulphuric acid is manufactured by the contact process. It involves the following steps:

Step (i):

Sulphur or sulphide ores are burnt in air to form SO₂.

Step (ii):

By a reaction with oxygen, SO₂ is converted into SO₃ in the presence of V₂O₅ as a catalyst.

2SO_2(g) + O_2(g)  2SO_3(g)

Step (iii):

SO₃ produced is absorbed on H₂SO₄ to give H₂S₂O₇ (oleum).

`SO_3+H_2SO_4 -> H_2S_2O_7`

This oleum is then diluted to obtain H₂SO₄ of the desired concentration.

In practice, the plant is operated at 2 bar (pressure) and 720 K (temperature). The sulphuric acid thus obtained is 96-98% pure

 

Answer 2

Preparation of sulphuric acid:By Contact Process: Burning of sulphur or sulphide ores in presence of oxygen to produce SO₂. Catalytic oxidation of SO₂ with O₂to give SO₃ in the presence of V₂O₅.

2SO₂(g) + O₂(g)  2SO₃(g)

Then SO₃ made to react with sulphuric acid of suitable normality to obtain a thick oily liquid called oleum.

`SO_3(g) + H_2SO_4(l) -> H_2S_2O_7(l)`

Then oleum is diluted to obtain sulphuric acid of desired concentration

`H_2S_2O_7(l) + H_2O(l) -> 2H_2SO_4(l)`

The sulphuric acid obtained by contact process is 96-98% pure