1. Do Now
How many possible reactions are there when Group 1 and 2 elements react with Group 7?
Which reaction would be the most reactive of them all?
Which reaction would be the least reactive of them all?
4. a) What would be produced when lithium reacts with chlorine?
b) What is being oxidised in this reaction?
c) What is being reduced in this reaction?
5. a) What would be produced when barium reacts with bromine?
c) What is being reduced in this reaction>

2. Experiment

3. What did we discover?
Question 1: a) No b) Iodide ion yes but chloride ion no c) Yes Question 2: Cl2(aq) + 2Br-(aq)  2Cl-(aq) + Br2(aq) Cl2(aq) + 2I-(aq)  2Cl-(aq) + I2(aq) Br2(aq) + 2I-(aq)  2Br-(aq) + I2(aq)

4. Colours when cyclohexane added
Chlorine  pale green colour does not change much
Bromine  orange colour looks a bit darker
Iodine  changes to purple/violet colour

5. 1 2 3 Chlorine water Bromine water Iodine solution Initial colour
Pale yellow-green to colourless 
Yellow-orange to colourless 
Yellow 1
Colour after shaking with KI solution
Colour of each layer after shaking with hexane
Upper
Purple
Lower
Brown
Orange/Brown
Conclusion – Iodine less reactive 2
Colour after shaking with KBr solution
Orange
Conclusion – Bromine is less than chlorine, more than iodine 3
Colour after shaking with KCl solution
Conclusion – Chlorine is more reactive

6. Cl2(aq) Br2(aq) I2(aq) Cl–(aq) Br–(aq) I–(aq)
© AS Jul-12

7. Stays yellow solution (no reaction)
Cl2(aq)
Br2(aq)
I2(aq)
Cl–(aq)
Stays yellow solution (no reaction)
Br–(aq)
I–(aq)
© AS Jul-12

8. Stays yellow solution (no reaction) Stays brown solution (no reaction)
Cl2(aq)
Br2(aq)
I2(aq)
Cl–(aq)
Stays yellow solution (no reaction)
Stays brown solution (no reaction)
Br–(aq)
I–(aq)
© AS Jul-12

9. Stays yellow solution (no reaction) Stays brown solution (no reaction)
Cl2(aq)
Br2(aq)
I2(aq)
Cl–(aq)
Stays yellow solution (no reaction)
Stays brown solution (no reaction)
Br–(aq)
Yellow solution forms (Br2 forms)
Cl2 + 2 Br-→ 2 Cl- + Br2
I–(aq)
© AS Jul-12

10. Stays yellow solution (no reaction) Stays brown solution (no reaction)
Cl2(aq)
Br2(aq)
I2(aq)
Cl–(aq)
Stays yellow solution (no reaction)
Stays brown solution (no reaction)
Br–(aq)
Yellow solution forms (Br2 forms)
Cl2 + 2 Br-→ 2 Cl- + Br2
I–(aq)
© AS Jul-12

11. Stays yellow solution (no reaction) Stays brown solution (no reaction)
Cl2(aq)
Br2(aq)
I2(aq)
Cl–(aq)
Stays yellow solution (no reaction)
Stays brown solution (no reaction)
Br–(aq)
Yellow solution forms (Br2 forms)
Cl2 + 2 Br-→ 2 Cl- + Br2
I–(aq)
Brown solution forms (I2 forms)
Cl2 + 2 I- → 2 Cl- + I2
© AS Jul-12

12. Stays yellow solution (no reaction) Stays brown solution (no reaction)
Cl2(aq)
Br2(aq)
I2(aq)
Cl–(aq)
Stays yellow solution (no reaction)
Stays brown solution (no reaction)
Br–(aq)
Yellow solution forms (Br2 forms)
Cl2 + 2 Br-→ 2 Cl- + Br2
I–(aq)
Brown solution forms (I2 forms)
Cl2 + 2 I- → 2 Cl- + I2
Br2 + 2 I- → 2 Br- + I2
© AS Jul-12

13. What is an oxidising agent?

14. Cl2(aq) + 2KBr(aq) → Br2(aq) + 2KCl(aq)
Displacement Reactions and Oxidising Power of Halogens
Cl2(aq) + 2KBr(aq) → Br2(aq) + 2KCl(aq)
Write down oxidation states under equation. Get rid of spectator ions and explain why chlorine is the oxidising agent using ½ equations.
Follow this with chemsheets halogen displacement experiment.

15. Oxidising power trend: Cl2 > Br2 > I2
When a halogen acts as an oxidising agent, it gains electrons (taken from the oxidised species).
X e- → 2 X- Cl Br I
Down the group it becomes harder to gain an electron because:
atoms are larger & there is more shielding (due to extra electron shell)

16. Explain why chlorine can displace both bromine and iodine
Chlorine has the strongest oxidising power. The increased shielding of extra shells reduces the effect of the increasing nuclear charge down the group. Since the chlorine has the smallest atomic radius it can accept electrons easier as they can get closer to the nucleus.

17. Finisher for 10!

19. Disproportionation reactions of chlorine
One element undergoes both oxidation and reduction at the same time.
Cl2 + H2O  HCl + HClO
HCl  hydrochloric acid
HClO  chloric(I) acid
Both colourless solutions

20. Disproportionation reactions of chlorine
One element undergoes both oxidation and reduction at the same time.
Chlorine with cold alkali
Cl2 + 2NaOH  NaCl + NaClO + H2O
NaClO  sodium chlorate(I)

21. Disproportionation reactions of chlorine
One element undergoes both oxidation and reduction at the same time.
Chlorine with hot concentrated alkali
3Cl2 + 6NaOH  5NaCl + NaClO3 + 3H2O
NaClO3  sodium chlorate (V)

22. Summary Questions
Write equation and name the products of the reactions between bromine and:
Cold dilute aqueous sodium hydroxide
Hot concentrated sodium hydroxide solution

23. Summary Questions
Write equation and name the products of the reactions between bromine and:
Br2 + 2NaOH  NaBr + NaBrO + H2O
3Br2 + 6NaOH  5NaBr + NaBrO3 + 3H2O