Halogen / halide displacement reactions

IGCSE Chemistry - Halogen / halide ion displacement reactions experiment

The chemicals used were as follows;

Halide ion solutions:
Potassium chloride, 0.1M
Potassium bromide, 0.1M
Potassium iodide, 0.1M

Halogens:
Chlorine water, unknown concentration
Bromine water, unknown concentration
Aqueous iodine, unknown concentration

Method:
1. Approximately 20ml potassium chloride was put into three 100ml conical flasks.

2. 20ml potassium bromide was put into three 100ml conical flasks.

3. 20ml potassium iodide was put into three 100ml conical flasks.

4. A few millilitres of aqueous iodine was added to one flask of potassium chloride, one flask of potassium bromide and one flask of potassium iodide and swirled.

5. Step 4 was repeated with bromine water and chlorine water as shown in the movie clip.

Colour changes due to displacement reactions were observed (are clearly visible in the movie clip).

Discusion:
Chlorine displaces both bromide and iodide ions from solution.
Bromine displaces iodide ions from solution.

This follows the reactivity trend for group 7 Halogens; any halogen will displace halide ions from aqueous solution of any members of the group below it in the Periodic Table.