Write the equations involved in the manufacture of sulphuric acid in contact process.

Explanation

In contact process `H_(2)SO_(4)` is manufactured as follows
Step 1 :- Production of `SO_(2)` : `SO_(2)` is produced by burning sulphur or iron pyrites in presence of air.
`S+O_(2)rarrSO_(2)`
`4FeS_(2)+11O_(2)rarr2Fe_(2)O_(3)+8SO_(2)`
The `SO_(2)` is purified by removing dust and other impurities like arsenic compounds.
Step 2 :- Oxidation of `SO_(2)` : The `SO_(2)` is subjected to oxidation in presence of vanadium pentaoxide `[V_(2)O_(5)]` catalyst at 720K and 2 atom pressure to form `SO_(3)`.
`2SO_(2)+O_(2)overset(V_(2)O_(3))underset("720 K. 2 atm")rarr 2SO_(2)`
Step 3 :- Absorption of sulphur trioxide :- `SO_(3)` gas is absorbed in conc. `H_(2)SO_(4)` in an absorption tower to get fuming sulphuric acid (or) oleum
`H_(2)S_(2)O_(7)+H_(2)Orarr 2H_(2)SO_(4)`.
Step 4 :- Dilution :- Oleum is diluted with calculated amount of water to get `98%` sulphuric acid called conc `H_(2)SO_(4)`.
`H_(2)S_(2)O_(7)+H_(2)Orarr2H_(2)SO_(4)`