Electrolytic Cells

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Electrolytic Cells
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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

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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?
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This time Zn is reduced Cu is oxidized
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Two kinds of electrolytic cells

• Fused Salt Cells purify metals
• (Fused means melted!)
• Plating Cells designing surface to have
  specific properties

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

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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

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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

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()
Cathode Obj being Plated
Reduction Cu2 2e- ? Cu
Note just moving Cu around
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Plating
Cathode object to be plated Anode - made of
metal want to plate on object Solution contains
ions of plating metal
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Fused Salt Cells

• Process used to purify metals from their ores

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Schematic of fused salt cell
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• Why does NaCl have to be molten?
• Which electrode will Na1 ions be attracted to?
• Which electrode will Cl-1 ions be attracted to?

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