Application of

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Application of Electrolytic Cells Lesson 11
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Electrolysis describes what happens in an
electrolytic cell and means to use electricity to
make chemicals. Many elements are made by
electrolysis Pb Al Zn Na K Li H2 Cl2 F2
I2 O2 Pb2 2e- ? Pb(s) 2Cl-
? Cl2(g) 2e- This is sometimes called
electrowinning- the element is won from its ion
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Making Aluminum by Electrolysis Alcan (70,000
employees in 55 countries) Kitimat B.C. 2.7
MT 7 world production
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Aluminum
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Aluminum Production by Electrolysis Name of
the Ore imported from (Guinea and
Brazil) Bauxite Al2O3.3H2O Heating drives off
the water Al2O3.3H2O Heat
? Al2O3 3H2O   Melting point of Bauxite is
2045 0C This is too hot! Cryolite is added
Lowers the melting point to 1000 0C
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Reduction of water
You cannot reduce Aluminum in water! It must be
molten!
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Liquid Al floats to the top and is removed
Oxygen gas
C
C
- Reduction Cathode Al3 3e- ? Al(s)
Oxidation Anode O2- ? 1/2O2(g) 2e-
Al3 O2-
Al2O3(l)
Cation Cathode Reduction
Anion Anode Oxidation
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Electroplating   Au plating a Cu
penny Electroplating is the process of reducing a
metal on to the surface of another Electrolyte Mu
st contain the ion of the metal that
plates Cathode The metal to be covered with a
new metal Anode Metal to be plated on top the
other metal  
DC Power -
e-
- Reduction Cathode Au e- ? Au(s)
Au
Oxidation Anode Au(s) ? Au 1e-
Au CN-
Cu
Cu
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ve
-ve
stainless steel or Au
AuCN
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Au plated
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Copper Ring
Gold Plated
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Tanyas Ring Gold Plated
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Electroplating   Ag plating a Loonie  
DC Power -
e-
- Reduction Cathode Ag e- ? Ag(s)
Ag
Oxidation Anode Ag(s) ? Ag 1e-
Ag NO3-
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Electrorefinning Lead Trail, B.C. Teck 16
mines in BC Major World Producer of Zn, Cu, Pb,
and Coal
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Lead Refinery-Trail
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The Electrorefinning of Lead   Electrorefining
is the process of purifying a metal by
electrolysis. The electrolyte must contain
Pb Impure metal is oxidized at the anode and pure
metal is reduced at the cathode. This is the same
as electroplating.      

DC Power -
Cathode Pure Pb
Anode Impure Pb
- Reduction Cathode Pb2 2e- ? Pb(s)
Pb2 NO3-
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The impurities in Pb are Au Ag Zn
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At the Anode
Au does not oxidize
The voltage is controlled so that
Ag does not oxidize
Pb oxidizes
Zn oxidizes
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At the Cathode
The voltage is controlled so that
Pb2 reduces
Zn2 does not reduce
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The Electrorefinning of Lead   Electrorefining is
the process of purifying a metal by
electrolysis. The electrolyte must contain
Pb Impure metal is oxidized at the anode and pure
metal is reduced at the cathode. This is the same
as electroplating.      

DC Power -
Cathode Pure Pb
Anode Impure Pb
- Reduction Cathode Pb2 2e- ? Pb(s)
Oxidation Anode Zn(s) ? Zn2 2e- Pb(s) ?
Pb2 2e-
Pb2 NO3-
Zn2
Au
Ag
Solid Au and Cu are released from the anode and
fall to the bottom
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Video of the thermite reaction used to make
Iron The Thermite reaction is very exothermic
and produces white hot molten iron. Fe2O3
2Al(s) ? Al2O3(s) 2Fe(l) energy