Electrolytic Cell Involves non spontaneous redox reactions Use external power supply to drive the redox reaction (like a battery or plug into wall) Amount of E needed to drive the reaction depends on the half reactions that make up the cell Eocell will be negative Ex. include electroplating and electrolysis of molten salts to the M (s) 2 NaCl (molten) → 2 Na (s) + Cl2 (g)

Electrolytic Cell, Parts Same as galvanic, still have Electrolytes Electrodes (cathode and anode) Salt bridge Still have AutO and CaR Anode gets oxidized Cathode gets reduced

How does it work? Have to put energy into an electrolytic cell to drive the redox rxn (non spont) Need to connect it to an external power supply (like a battery/galvanic cell) The - end of battery (anode) hooks to cathode in EC The + end of battery (cathode) hooks to anode in EC

Electrolysis of Water Zap H2O to decompose it to elements 2 H2O → 2 H2 + O2 Who is oxidized? Who is reduced? Write balanced half reactions. (note: H2 half reaction is basic, O2 is acidic)

Electrolysis of Water Yellow = Acidic 2 H2O → O2 + 4 H+ + 4 e- Blue = Basic 2 H2O + 2 e- → H2 + 2 OH-

Electrolysis of Molten Salts Process to extract free metal from ores (salts) Zap molten solution of ore with energy, and get elements Molten salt is like an aqueous solution, the ions are separated Ex. Electrolysis of Molten NaCl Na+ + Cl- → Na + Cl2 Who is oxidized? Reduced? Write half reactions and NIE. Draw a pic of cell. Calc Eocell. Does sign make sense? Interpret in words. Na/Na+ = -2.71 V Cl2/Cl- = 1.36 V

Metal in Ore Gets Reduced Nonmetal Gets Oxidized If you have a mixture of salts like KCl and NaCl, which metal will get reduced first? Na+ + e- → Na Eo = -2.71 V K+ + e- → K Eo = -2.92 V Which anion would get oxidized more easily?

Quantitative Aspect of Electrolysis See sheet