1. Electrolytic Cells

2. Electrolytic Cells
electricity used to force non-spontaneous reactions to occur = Endothermic
electrolytic cells identified by presence of battery or power supply
many kinds of electrolytic cells

3. Galvanic Cell
Chemical
Potential
Energy
Electrical
Potential
Energy
Electrolytic Cell

4. Electrolytic Decomposition of H2O
H2 produced at one electrode, O2 at other
2H2O + energy 2H2 + O2
Can you tell from the picture which electrode is producing H2?

5. Reversing a Galvanic Cell
This time:
Zn is reduced & Cu is oxidized

6. Two kinds of electrolytic cells
Fused Salt Cells – purify metals
(Fused means melted!)
Plating Cells – designing surface to have specific properties

8. Electroplating
Move desired coating from anode onto object to be plated
Solution contains ions of element to be plated

9. Electroplating: Cu onto Al
Al above Cu in Table J
reaction will not happen spontaneously
use external energy source (power supply or battery) to force reaction to occur

10. An Ox ate a Red Cat Anode: electrode at which oxidation occurs
Cathode: electrode at which reduction occurs
Polarity electrodes different than galvanic cell!
Anode is positive
Cathode is negative

11. A POX on Electrolytic Cells
Anode – Positive – Oxidation
electrolytic cell, polarity determined by outside power supply
anode hooked up to (+) terminal
cathode hooked up to (-) terminal
Look at drawings in Regents questions

12. (+) (-) (+) (-) Anode = Oxidation Cu  Cu+2 + 2e- Battery
Cathode = Obj being Plated
= Reduction
Cu e-  Cu
(-)
Note: just moving Cu around
Cu+2 and SO4-2

14. Plating Cathode = object to be plated
Anode - made of metal want to plate on object
Solution: contains ions of plating metal
Plating

15. Fused Salt Cells
Process used to purify metals from their ores

16. Schematic of fused salt cell+ - + -
Ox: 2Cl-  Cl2 + 2e-
Red: Na+ + 1e-  Na

17. Why does NaCl have to be molten?
Which electrode will Na+1 ions be attracted to?
Which electrode will Cl-1 ions be attracted to?