When concentrated sulphuric acid is added to an inorganic mixture containing chloride ,we get colourless pungent smelling gas HCI, but if the mixture contains bromide then we get red vapour of bromine .Why?

Explanation

When concentrated `H_(2)SO_(4)` is added to an inorganic misture containing chloride HCI .Which has a pungent smell is produced
`underset(("chloride salt"))(2MCI)+underset(("concentrated"))(H_(2)SO_(4))tounderset(("M=Na,K"))(2MHSO_(4))+2HCIuarr`
As HCI is a weak reducing agent ,it cannot reduce `H_(2)SO_(4)` and is not oxidised to `CI_(2)` .So the following reaction is not possible .
`2HCI+underset(("concentrated"))(H_(2)SO_(4))(cancelto)CI_(2)+SO_(2)+2H_(2)O`
If the concentrated `H_(2)SO_(4)` is added to an inorganic mixture containing bromide. HBr is formed intially. However Hbr being a strong reducing agent. reduces `H_(2)SO_(4)`to`SO_(2)`and itself gets oxidised to `Br_(2)` vapour ,which is red in colour.
`2MBr+H_(2)SO_(4)to2MHSO _(4)+2HBruarr`
`2HBr+H_(2)SO_(4)toBr_(2)+SO_(2)+2H_(2)O`