Chemical Test For Bromine 3 :

Action with starch-iodide paper :

Bromine gas also turns damp starch iodide paper deep blue / blue black coloured complex.

Just like chlorine, Bromine first reacts with KI (aq) in the starch iodide paper :

Br₂ (l)     +     2KI (aq)       →   2KBr (aq)       +                                         I₂ (aq)

                                                                           Here I₃^- Ion formed which is actually soluble in water   not I^- Ion

Then iodine that is formed will react with starch in the starch-iodine Paper  :

I₂ (aq)      +       Starch  →       blue black / deep blue coloured complex