1. 1.5c Learning Outcomes
carry out an experiment to demonstrate the displacement reactions of metals (Zn with Cu2+, Mg with Cu2+)
explain what happens at each electrode during the electrolysis of:
copper sulfate solution with copper electrodes
acidified water with inert electrodes
(half equations only required)

2. Learning Outcomes
describe and account for the observations of what happens at each electrode during the electrolysis of (teacher demo):
-aqueous sodium sulfate (using universal indicator)
-aqueous potassium iodide (using phenolphthalein indicator) with inert electrodes (half equations only required)

3. Learning Outcomes
describe the extraction of copper by displacements using scrap iron
describe and explain ionic movement as observed during teacher demonstration 
describe the following electrolytic processes: chrome and nickel plating. Give one everyday application of chrome and nickel plating e.g. cutlery

4. Learning Outcomes Use of scrap iron to extract copper.
Electroplating. Purification of copper.
Chrome and nickel plating. Cutlery.

5. Displacement
More reactive Reducing Agent metal displaces less reactive from a solution
Mg + CuSO4 = MgSO4 + Cu
Mg + Cu+2  Mg+2 + Cu
Mg loses electrons (Oxidised => Red Agent)
Cu+2 gains electrons (Reduced => displaced)

6. 1. To Show the Displacement of Copper using Zinc
Method:
Place Zinc in copper sulfate solution
Leave for a few minutes
Result: Solution turns from Blue to Colourless because copper sulfate has become zinc sulfate [copper displaced out by zinc]. Copper powder forms at the bottom of the beaker

7. 2. To Show the Displacement of Copper using Magnesium
Method:
Place Magnesium in copper sulfate solution
Leave for a few minutes
Result: Solution turns from Blue to Colourless because copper sulfate has become magnesium sulfate [copper displaced by magnesium]. Copper powder forms at the bottom of the beaker

8. Electrolysis Discovered by H Davy
Used it to extract reactive group I and group II elements e.g. Na and K
Extraction of Al

9. Definitions
Electrolysis: Chemical reaction caused by the passage of an electric current through a liquid known as the electrolyte.
Electrolyte: liquid in which electrolysis takes place. Usually an ionic solution but it can also be a fused [melted] ionic compound
Anode: positive electrode. Positive because the battery sucks electrons out of it
Cathode: Negative electrode. Negative because the battery pumps electrons into it.

10. Anion: negative ion. Called anion because it is attracted to the opposite charge of the anode
Cation: positive ion. Called cation because it is attracted to the opposite charge of the cathode.
Inert Electrodes: do not react with the electrolyte. Graphite and Pt
Active electrodes: react with electrolyte e.g. Copper and iron
Reduction: gain of electrons - occurs at cathode
Oxidation: loss of electrons – occurs at anode
OIL RIG: oxidation is loss – reduction is gain

11. Electrolysis Reactions
Copper sulphate using active electrodes [Cu] {Purification of Copper}
Water using Pt electrodes [inert] [dilute H2SO4 – catalyst]
Potassium iodide using inert electrodes [Pt]
Sodium sulphate using inert electrodes [Pt]

12. 1. CuSO4 using Cu electrodes (active electrodes)

13. - CuSO4 with copper electrodes Cathode reaction
Cu deposited on cathode is 99.9% pure
Battery e- pump - + e-
Cu2+ ions attracted by opposite charge of cathode
e-s are replaced immediately e- e- e- e-
Cu2+(aq) + 2e- = Cu(s) e- e- e- e- e-
Cu2+(aq) make the solution blue e-
Cathode is negative because battery pumps e- into it

14. - CuSO4 with copper electrodes Battery e- pump Anode reaction e- +
Cu2+ ions are
Smaller than the atom
Soluble in water
Repelled by similar charge of anode e-
Cu2+ e- e-
Cu(s) - 2e- = Cu2+(aq) e- e- e- e- e- e- e- e-
Anode is positive because battery pumps e- out of it
Impurities e.g. Ag, Au, Pt fall to the bottom

15. CuSO4 using copper electrodes [active]
Anode reaction [+ battery sucks electrons out]
Cu(s) – 2e- = Cu2+(aq) or Cu(s) = Cu2+(aq) + 2e-
Cu is oxidised - Loss of electrons
Anode loses mass as copper dissolves off
Impurities fall to bottom
Cathode reaction
Cu2+(aq) + 2e- = Cu(s)
Cu2+ is reduced - Gain of electrons
Cathode gains mass as Cu is deposited on it
Cu is 99.9% pure

16. 2. H2O using Pt electrodes

17. Acidified water using Hoffman’s voltameter

18. H2(g) is formed when two H atoms meet
Cathode
e- rich e- e-
OH- e- e- e-
OH- makes solution alkaline which turns phenolphthalein pink e- e- H2 H e- e- e-
H2(g) is formed when two H atoms meet e- e- H e- e- e- e- e-
OH- e-
2 H2O + 2 e- = H2 + 2 OH- e-

19. Anode removes 2e- from H2O forming 2 H+ and an O atom
O atoms react forming O2 which escapes as oxygen gas
H+ makes the solution acidic which turns litmus red H+ e- H+
Anode (+ve)
Because battery pulls e-s from it
2 H2O – 4e- = 4H+ + O2

20. Dilute sulphuric acid (H2SO4) acts as a catalyst
Hydrogen produced at cathode
2 H2O + 2 e- = H2 + 2 OH-
Burns with a sqeeky pop
Oxygen produced at anode
2 H2O – 4e- = 4H+ + O2
2 H2O = 4H+ + O2 + 4e-
Relights a glowing splint
Volumes 2 H2 : 1O2

21. 3. Na2SO4 using Pt electrodes

22. Anode removes 2e- from H2O forming 2 H+ and an O atom
O atoms react forming O2 which escapes as oxygen gas
H+ makes the solution acidic which turns litmus red H+ e- H+
Anode (+ve)
Because battery pulls e-s from it
2 H2O – 4e- = 4H+ + O2

23. H2(g) is formed when two H atoms meet
Cathode
e- rich e- e-
OH- e- e- e-
OH- makes solution alkaline which turns phenolphthalein pink e- e- H2 H e- e- e-
H2(g) is formed when two H atoms meet e- e- H e- e- e- e- e-
OH- e-
2 H2O + 2 e- = H2 + 2 OH- e-

24. Na2SO4 using inert electrodes [Pt]
Anode
2 H2O = 4 H+ + O e-
Litmus goes red
Cathode
2 H2O + 2 e- = H2 + 2 OH-
Litmus goes blue

25. 4. KI using Pt electrodes

26. H2(g) is formed when two H atoms meet
Cathode
e- rich e- e-
OH- e- e- e-
OH- makes solution alkaline which turns phenolphthalein pink e- e- H2 H e- e- e-
H2(g) is formed when two H atoms meet e- e- H e- e- e- e- e-
OH-
2 H2O + 2 e- = H2 + 2 OH- e- e-

27. Colourless negative are ions attracted by opposite charge of anode
Two iodine atoms react to form brown iodine molecules I2 I I- e-
An electron is stripped off each ion forming two iodine atoms
Anode (+ve)
Because battery pulls e-s from it
2 I e- = I2

28. KI using inert electrodes [Pt]
Anode reaction
2 I- = I2 + 2 e-
Solution goes brown as Iodine forms
I- is oxidised – loss of e-
Cathode reaction
2 H2O + 2 e- = H2 + 2 OH-
Phenolphthalein goes pink
Due to OH- being formed

29. Use of scrap iron to extract copper.
(Dissolved CuSO4) + (Metallic Fe) ==> (Dissolved FeSO4) + (Metallic Cu)

30. Electrolysis
Chemical reaction caused by the passage of an electric current through a liquid known as the electrolyte

31. Uses of Electrolysis 1. Producing reactive metals e.g Na, K, Al
2. Producing hydrogen and oxygen
3. Purifying copper (99.9% pure)
4. Electroplating e.g. EPNS

32. Electroplating Electroplating
Covering cathode in metal e.g. Cu by making it cathode in copper sulphate solution

33. Copper Plating
Metal being plated is present at the anode and at in the electrolyte e.g. Ni or Cr

34. Copper Plating Cu2+(aq) + 2e- = Cu(s) Cu(s) = Cu2+(aq) + 2e-
Anode reaction
Cu(s) = Cu2+(aq) + 2e-
Anode loses mass as copper dissolves off
Impurities [Au, Ag, Pt etc.] fall to bottom
Cathode reaction
Cu2+(aq) + 2e- = Cu(s)
Cathode gains mass as Cu is deposited on it
Cu is 99.9% pure

35. Application of Cr and Ni Plating
application of chrome and nickel plating e.g. cutlery