Two layer mixtures change color.
name: Halogens displace each other from compounds according to their activity.
Wear eye protection goggles. Care with chlorine and bromine solutions. Perform experiment in well ventilated room.
Always follow general safety
recommendations. Please note that conducting chemistry
experiments you must comply with the relevant legal procedures in
In this experiment the displacement halogen reactions are demonstrated. The halogen’s activity and ability to displace each other from compounds changes according to their position in periodic table. Reactivity decreases down Group 7. On atomic level it means that the larger the radius of the halogen atom the less activity it possess. Fluorine is the most reactive halogen. Chlorine is less reactive than fluorine but more reactive than bromine. Iodine is the least active. Thus in the first part of the experiment chlorine dissolved in water displaces bromine and iodine ions and has no impact on potassium fluoride solution. Bromine and iodine move out of the compound and come to the top layer, since halogens are more soluble in cyclohexane than in water. Small concentration of bromine turns the solution yellow as well as small concentration of iodine makes the solution violet.
In the second part of the experiment bromine water is tested for the halogen displacement reactions. Similarly to the case of chlorine water and potassium fluoride, bromine could not displace fluorine and chlorine ions from their compounds. Reaction is possible only in the case of the least active iodine.