1. Topic 3 revision: Electrolytic Processes

2. What is electrolysis?
Breaking down an ionic substance using electricity.
Metals have a positive charge and non metals have a negative charge.
Hydrogen is an exception (it is a non metal with a positive charge.

3. Anode
Cathode
= bromide ion
= lead ion

4. What happens at the electrodes?
Use the electrolysis of lead bromide as an example.
The ions discharge and elements re-form.
So, at the anode bromine forms and at the cathode lead forms.

5. Ionic half equations Electrolysis of CuCl2 Anode: 2Cl-  Cl2 + 2e-
Cathode: Cu e-  Cu
Electrolyse these:
CaF2
AlBr3

6. Electrolyus 2H+ + 2e-  H2 2Cl-  Cl2 + 2e-
Na+ and OH- are left behind to create NaOH in the solution.
Only the least reactive element will form at the electrode.
This is not needed but you may wish to share this with G+T.

7. At the anode
anode
anode e- Cu
Cu2+ e- Cu
Cu2+
Cu  Cu2+ + 2e-

8. At the cathode Cu2+ + 2e-  Cu cathode Cu2+ cathode cathode e- Cu e-
Pure
Copper
Cu2+ + 2e-  Cu

9. What about the impurities
anode
anode
As the anode dissolves
The impurities are released
They sink to the bottom
As anode slime Pt Ag Au
Valuable stuff
Anode Slime

10. Refining copper At the positive anode
Copper atoms lose electrons and become copper ions.
The positive ions drift away from the anode
Cu  Cu2+ + 2e-
The anode dissolves
At the negative cathode
Positive copper ions drift to the cathode.
They gain electrons and become copper atoms
Cu2+ + 2e-  Cu
The cathode is electroplated

11. Electroplating Two uses: To galvanise metals (to stop corrosion)
To make things more attractive.