Mandatory Experiment: Redox Reactions of the Halogens

Chemistry Page

Equipment:

Test tubes
Chlorine solution
Bromide solution
Bromine solution
Iodide solution

(i) Reactions with Halides

1. Add 2cm³ chlorine solution and 2cm³ sodium bromide solution to seperate test tubes and mix.
2. Add 2cm³ chlorine solution and 2cm³ potassium iodide solution to seperate test tubes and mix.
3. Add 2cm³ bromine solution and a potassium iodide solution to separate test tubes and mix.

Results

1. An orange colour forms. This shows that bromine has been formed (released from its salt)
2. A brown colour forms. This shows that iodine has been formed (released from its salt)
3. A brown colour forms. This shows that iodine has been formed (released from its salt)

(ii) Reactions with Iron(ii) salts with sulfites

Equipment:

Chlorine solution
Iron (II) Sulfate solution
Sodium Hydroxide solution
Bromine Solution
Iodine Solution
Sodium Sulfite solution
Barium Chloride solution
Dilute Hydrochloric acid

1. Add 2cm³ chlorine solution and 2cm³ iron(ii) sulfate solution to seperate test tubes and mix.
   
2. Add 10 drops sodium hydroxide solution.
3. Repeat using bromine solution instead of chlorine solution.
4. Repeat using iodine solution instead of chlorine solution.
5. Add 2cm³ chlorine solution and 2cm³ sodium sulfite solution to separate test tubes and mix. Add a few drops barium chloride solution and 2cm³ dilute hydrochloric acid.
6. Repeat using bromine solution instead of chlorine solution.
7. Repeat using iodine solution instead of chlorine solution.

Results:

1. A greenish-brown precipitate is formed, indicating the presence of Fe3+ ions (released from its salt)
2. A greenish-brown precipitate is formed, indicating the presence of Fe3+ ions (released from its salt)
3. A greenish-brown precipitate is formed, indicating the presence of Fe3+ ions (released from its salt)
4. A white precipitate insoluble in HCl is formed, indicating sulfate ions (released from its salt)
5. A white precipitate insoluble in HCl is formed, indicating sulfate ions (released from its salt)
6. A white precipitate insoluble in HCl is formed, indicating sulfate ions (released from its salt)