When Cl₂ water is added to an aqueous solution of potassium halide in the presence of chloroform, a violet color is obtained. On adding more of Cl₂ water, the violet color disappears and a colorless solution is obtained. This test confirms the presence of the following in aqueous solution

Cl₂ is a strong oxidizing agent than I₂ because of its high electronegativity. When, Cl₂ reacts with KI in the presence of CCl₄, it forms I₂ and the color of the solution becomes pink.

${\mathrm{Cl}}_2+2\mathrm{KI}\to 2\mathrm{KCl}+\underset{\mathrm{Voilet} \mathrm{color}}{{\mathrm{I}}_2}$

If more Cl₂ is added, then I₂ further oxidized to HIO₃.Therefore, color of solution becomes colorless.

$\underset{\mathrm{Voilet}}{{\mathrm{I}}_2}+5{\mathrm{Cl}}_2\stackrel{6{\mathrm{H}}_2\mathrm{O}}{\to }\underset{\mathrm{Colorless}}{2{\mathrm{HIO}}_3}+10\mathrm{HCl}$

This test shows the presence of iodide in the solution.