With the help of equations, give an outline for the manufacture of sulphuric acid by the contact process.

Explanation

`S+ O_2 rarr underset(underset("dioxide")("Sulphur"))(SO_2)`
`underset(underset("dioxide")("Sulphur"))(SO_2) + O_2 underset(450^@C)overset(V_2O_5)to underset(underset("trioxide")("Sulphur"))(2SO_3)`
`SO_3 + underset("(Conc.)")(H_2SO_4) rarr underset("Oleum")(H_2S_2O_7)`
`H_2S_2O_7+ H_2O rarr underset("Sulphuric acid")(2H_2SO_4)`