Question

Describe the principle and process for the manufractured of sulphuric acid witha a well labeled diagram by contact process.

Answer 1

The steps involved in the manufacture of sulphuric acid by contact process:

(1) Sulphur (or iron pyrites) are burnt in air to form sulphur dioxide.

  S+O2→SO24FeS2+11O2→2Fe2O3+8SO2

(2) Catalytic oxidation of sulphur dioxide to sulphur trioxide.

  2SO2+O2V2O52SO3ΔrHo=−196.6kJ

The reaction is reversible and exothermic.

(3) Sulphur trioxide is dissolved in 98% sulphuric acid to form oleum (fuming sulphuric acid). 

  SO3+H2SO4→H2S2O7

(4) Oleum is diluted with water to form sulphuric acid of desired concentration.

    H2S2O7+H2O→2H2SO4

            and

Manufacture of H2SO4 by contact process involves three steps:

1. Burning of sulphur in air to generate SO2.

2. Conversion of SO2 to SO3 by oxidation with air in the presence of