Reaction of Concentrated sulfuric acid with metal bromide :

Again, Sulphuric acid reacts with Metal bromide to form HBr :

e.g.         KBr (s)      +    H₂SO₄ (l)  → HBr  (g)   +    KHSO₄   (s)

This is the primary reaction that would occur in every reactions of Concentrated sulfuric acid with Metal Halide.

If you have remembered from early reaction with metal chloride, HCl can’t reduces H₂SO₄ further whereas HBr can. HBr can reduces H₂SO₄ once.

This HBr then further reduces H₂SO₄ to SO₂

     (-1)                         (+6)                                     ( 0 )                                   (+4)

HBr (g) +   H₂SO₄ (l)  → Br₂ (g)  +   SO₂ (g)  + 2H₂O (l) 

Here  HBr reduces Sulphur in sulphuric acid from +6 to +4 in SO₂

Here two reactions are occurring.

Observations :

1)  Steamy / Misty fumes due to HBr gas.

2)  Red brown vapour due to Br₂ gas.

** Bromine i.e. formed here is in the gaseous state since the reaction is exothermic.