1. 1 Lec. 2 Faraday’s Laws Lec. 2 Faraday’s Laws Industrial Electrolytic Processes “Electrolysis”

2. 2 What you should learn What is electrolysis? Faraday's laws of electrolysisFaraday's laws of electrolysis Industrial Applications of electrolytic processIndustrial Applications of electrolytic process

3. 3 It is used industrially in a number of ways: 1.Electroplatig. 2.The preparation of gases, notably chlorine. 3.Water decomposition. 4.The extraction of metals, notably aluminum, magnesium, and sodium. 5.The refining of metals, such as copper and zinc.

4. 2. Electrolysis of Molten Salts and Production of Cl2 4

5. +- battery Na (l) Cathode Anode Molten NaCl Na + Cl - Na + Na + + e -  Na 2Cl -  Cl 2 + 2e - Cl 2 (g) escapes Observe the reactions at the electrodes NaCl (l) (-) Cl - (+)

6. Molten NaCl Electrolytic Cell cathode half-cell (-) REDUCTION Na + + e -  Na anode half-cell (+) OXIDATION 2Cl -  Cl 2 + 2e - overall cell reaction 2Na + + 2Cl -  2Na + Cl 2 X 2

7. 7 Electrolysis of Diluted NaCl

8. battery +- power source e-e- e-e- NaCl (aq) (-)(+) cathode different half-cell Aqueous NaCl anod ee 2Cl -  Cl 2 + 2e - Na + Cl - H2OH2O What could be reduced at the cathode?

9. Aqueous NaCl Electrolytic Cell possible cathode half-cells (-) REDUCTION Na + + e -  Na 2H 2 0 + 2e -  H 2 + 2OH - possible anode half-cells (+) OXIDATION2Cl -  Cl 2 + 2e - 2H 2 O  O 2 + 4H + + 4e - overall cell reaction 2Cl - + 2H 2 0  H 2 + Cl 2 + 2OH -

10. 3. Water electrolysis 10

11. 11 The Electrolysis of Water containing some sulfates 2 H 2 O + 2e -  H 2 (g) + 2 OH - cathode reaction 2H 2 O  O 2 (g) + 4H + + 4e - anode reaction Cell diagram Battery, a source of direct current e - flow Cathode Anode e - flow aqueous K 2 SO 4 O 2 gas H 2 gas + pole of battery- pole of battery

12. 12 The Electrolysis ofwater

13. 4. Extraction of Metals 13

14. carbon-lined steel vessel acts as cathode CO 2 bubbles Al (l) Al 2 O 3 (l) Draw off Al (l) - + Cathode: Al +3 + 3e -  Al (l) Anode: 2 O -2 + C (s)  CO 2 (g) + 4e - from power source Al +3 O -2 Al +3 O -2 graphite anodes  e- e- e- e- 

15. The Hall Process Cathode: Al +3 + 3e -  Al (l) Anode: 2 O -2 + C (s)  CO 2 (g) + 4e - 4 Al +3 + 6 O -2 + 3 C (s)  4 Al (l) + 3 CO 2 (g) x 4 x 3 The graphite anode is consumed in the process.