The more reactive halogen displaces the less reactive halogen from its compound in aqueous solution.Of chlorine, bromine and iodine, chlorine is the most reactive because it is the smallest atom so the incoming electron gets closest to the nucleus and experiences the strongest nuclear attraction.Any reaction is indicated by a colour change.
Cl2 + 2 NaBr → Br2 + 2 NaClcolour changes from colourless to orange/red
Cl2 + 2 NaBr → Br2 + 2 NaClcolour changes from colourless to orange/red
Colours of Halogens
Halogens are more soluble in organic solvents such as cyclohexane than water. If cyclohexane is added to an aqueous solution of halogen, the halogen dissolves in the upper organic layer so the colours can more clearly be seen.