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How do you account for the following obs...

How do you account for the following observations ?
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?

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When we add conc. `H_(2)SO_(4)` to inorganic mixture containing chloride, the less volatile acid `H_(2)SO_(4)` displaces the more volatile acid HCl. The pungent smelling gas (HCl) is obtained.
`2NaCl(s) + H_(2)SO_(4)(l) rarr 2NaHSO_(4)(s) + 2HCl(g)`
As HCl is weak reducing agent, it cannot reduce `H_(2)SO_(4) " to " SO_(2)`. If the mixture contains bromide, the more volatile acid HBr is displaced. HBr being a stronger reducing agent, reduces `H_(2)SO_(4) " to " SO_(2)`, and itself get oxidised to bromine which evolves as red vapour.
`2NaBr + H_(2)SO_(4) rarr 2NaHSO_(4) (s) + 2HBr`
`2HBr + H_(2)SO_(4) rarr SO_(2) + 2H_(2)O + underset(("Red vapour"))(Br_(2)(g))`
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