Describe the manufacture of `H_(2)SO_(4)` by contact process.

Explanation

Manufacture of `H_(2)SO_(4)` by contact process :
Manufacturing of `H_(2)SO_(4)` involves three main steps.
Step - I
`SO_(2)` production : The required `SO_(2)` for this process is obtained by burning S(or) Iron pyrites in oxygen.
`S+O_(2)toSO_(2)`
`4FeS_(2)+15O_(2)to2Fe_(2)O_(3)+8SO_(3)`
Step - 2
`SO_(3)` formation : `SO_(2)` isd oxidised in presence of catalyst with atmosphric air to form `SO_(3)`
`2SO_(2(g))+O_(2(g))underset(Delta)overset("catalyst")iff2SO_(3(g))`
Step - 3
Formation of `H_(2)SO_(4)` : `SO_(3)` formed in the above step absorbed in `98% H_(2)SO_(4)` to get oleum `(H_(2)S_(2)O_(7))`. This oleum is diluted to get desired concentration of `H_(2)SO_(4)`.
`SO_(3)+H_(2)SO_(4)toH_(2)S_(2)O_(7)`
`H_(2)S_(2)O_(7)+H_(2)O to2H_(2)SO_(4)`