Chlorine + Iron
3Cl2 + 2Fe → 2FeCl3
Observation
The iron wool burns vigorously with a bright flame, forming a brown solid after the reaction.
Discussion
- Chlorine reacts with iron to form brown iron(III) chloride.
- The reaction of potassium with concentrated hydrochloric acid produces chlorine gas.
2KMnO4 + 16HCl → 2KCl + 2MnCl2 + 5Cl2 + 8H2O
Bromine + Iron
3Br2 + 2Fe → 2FeBr3
Observation
The iron wool glows brightly but less vigorously. A brown solid is formed.
Discussion
Bromine reacts with iron to form brown iron(III) bromide.
Iodine + Iron
3I2 + 2Fe → 2FeI3
Observation
The iron wool glows slowly with dim light. A brown solid is formed after the reaction.
Discussion
Iodine reacts with iron to form brown iron(III) iodide.
Important Note
- Halogen is a reactive non-metal. It forms a salt when reacting with metals.
- The reactivity decreases down the group.
- Chlorine gas is poisonous. Excess chlorine gas is absorbed by the soda lime (sodium hydroxide) so that it does not escape to the surrounding.
- Iron wool rather than the iron piece is used to increase the rate of reaction.