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?

How do you account for the following observations ? When concentrated

1.	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?
Answer» Solution :When conc. `H_(2)SO_(4)` is added to an inorganic mixture containing chloride, the less volatile acid `H_(2)SO_(4)` displaces more volatile acid HCl and a pungent smelling gas (HCI) is obtained. <BR> `2NaCl(s)+H_(2)SO_(4)(L)to2NaHSO_(4)(s)+2HCl(g)` HCI being a weaker reducing agent is unable to reduce `H_(2)SO_(4)` to `SO_(2)`. When the mixture contains a bromide, the more volatile acid HBR is DISPLACED. HBr is a stronger reducing agent and REDUCES `H_(2)SO_(4)` to `SO_(2)`. It itself gets oxidised to bromine which evolves as red vapour. `2NaBr+H_(2)SO_(4)to2NaHSO_(4)+2HBr` `2HBr+H_(2)SO_(4)toSO_(2)+2H_(2)O+underset(("Red vapour"))(Br_(2)(g))`