Question

What is the "Layer Test" to identify Br and I anions?​

Answer 1

A Layer test to identify I anions is that they show Violet color and Br anions is that they show orange-yellow color.

• Layer test involves redox reactions among halides and it is used to find the presence of Iodide and Bromide ion in solution.

• The order of reactivity decreases down the halide group: Iodide, Bromide, chloride, Flouride.

• When Iodide is oxidized by chlorine to form iodine.  The Chloroform layer shows a violet color due to the presence of iodine.

                2I- + Cl2 -> I2+ 2Cl-

• To aqueous layer of bromide ion add chlorine which then oxidises to give bromine. The Chloroform layer shows a yellow-orange color due to the presence of bromine.

               2Br- + Cl2 -> Br2 + 2Cl-