1. Electrolysis non-spontaneous reaction is caused by the passage of an electric current through a solution

3. Electrolysis Electrolysis of Sodium chloride (chlor-alkali process) molten reactants =>liquid sodium and chlorine gas aqueous reactants => caustic soda (sodium hydroxide) and chlorine gas

4. Electrolysis Preparation of Aluminum (Hall process)

5. Electrolytic Refining of Copper Cu (s) + Cu +2 (aq) --> Cu +2 (aq) + Cu (s) impure pure anode cathode impurities: anode mud; Ag, Au, Pb

7. Quantitative Aspects of Electrolysis 1 coulomb = 1 amp sec 1 mole e - = 96,500 coulombs

8. Electroplating EXAMPLE: How many grams of chromium can be plated from a Cr +6 solution in 45 minutes at a 25 amp current?

9. Electroplating EXAMPLE: How many grams of chromium can be plated from a Cr +6 solution in 45 minutes at a 25 amp current? (45 min) #g Cr = ------------

10. Electroplating EXAMPLE: How many grams of chromium can be plated from a Cr +6 solution in 45 minutes at a 25 amp current? definition of minute (45 min)(60 sec) #g Cr = --------------------- (1 min)

11. Electroplating EXAMPLE: How many grams of chromium can be plated from a Cr +6 solution in 45 minutes at a 25 amp current? (45) (60 sec) (25 amp) #g Cr = --------------------------- (1)

12. Electroplating EXAMPLE: How many grams of chromium can be plated from a Cr +6 solution in 45 minutes at a 25 amp current? definition of a coulomb (45)(60 sec)(25 amp)(1 C) #g Cr = ----------------------------- (1) (1 amp sec)

13. Electroplating EXAMPLE: How many grams of chromium can be plated from a Cr +6 solution in 45 minutes at a 25 amp current? Faraday’s constant (45)(25)(60)(1 C)(1 mol e - ) #g Cr = ---------------------------------- (1)(1)(96,500 C)

14. Electroplating EXAMPLE: How many grams of chromium can be plated from a Cr +6 solution in 45 minutes at a 25 amp current? atomic weight (45)(60)(25)(1)(1 mol e - )(52 g Cr) #g Cr = ------------------------------------------- (1)(1)(96,500) (6 mol e - )

15. Electroplating EXAMPLE: How many grams of chromium can be plated from a Cr +6 solution in 45 minutes at a 25 amp current? (45)(60)(25)(1)(1 mol e - )(52 g Cr) #g Cr = ------------------------------------------- (1)(1)(96,500)(6 mol e - ) = 58 g Cr

17. Corrosion O 2(g) + 4 H + (aq) + 4 e - -----> 2 H 2 O (l) E o = 1.23 V Rusting Fe (s) -----> Fe +2 (aq) + 2 e - E o = 0.44 V O 2(g) + 4 H + (aq) + 4 e - -----> 2 H 2 O (l) E o = 1.23 V ------------------------------------------- -------------- 2 Fe (s) + O 2(g) + 4 H + (aq) -----> 2 H 2 O (l) + Fe +2 (aq) E o = 1.67 V

18. Preventing Corrosion painting galvanizing sacrificial anode