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how will we make sulphuric acid
Sulphuric acid is produced from sulphur, oxygen and water via the conventional contact process (DCDA) or the wet sulfuric acid process (WSA).
Contact process

In the first step, sulfur is burned to produce sulfur dioxide.
S(s) + O2(g) ? SO2(g)
This is then oxidized to sulphur trioxide using oxygen in the presence of a vanadium(V) oxide catalyst. This reaction is reversible and the formation of the sulphur trioxide is exothermic.
 2SO2(g) + O2(g) is in equilibrium with 2SO3(g)(in presence of V2O5)

The sulphur trioxide is absorbed into 97–98% H2SO4 to
form oleum (H2S2O7), also known as fuming sulphuric acid. The oleum is then diluted with water to form concentrated sulphuric acid.
H2SO4(l) + SO3(g)? H2S2O7(l)
H2S2O7(l) + H2O(l) ? 2H2SO4(l)
Note that directly dissolving SO3 in water is not practical due to the highly exothermic nature of the reaction between sulphur trioxide and water. The reaction forms a corrosive aerosol that is very difficult to separate, instead of a liquid.
SO3(g) + H2O(l) ? H2SO4(l)


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