Download - Application of Electrolytic Cells Lesson 11
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Application ofElectrolytic Cells
Lesson 11
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Electrolysis describes what happens in an electrolytic cell andmeans 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 ElectrolysisAlcan (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 waterAl2O3
.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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CC
DC Power
- +
Al3+
O2-
-
Reduction
Cathode
Al3+ + 3e- → Al(s)
+
Oxidation
Anode
O2- → 1/2O2(g) + 2e-
Liquid Al floats to the top and is removed
Oxygen gas
Al2O3(l)
Cation Cathode Reduction Anion Anode Oxidation
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Au+
CN-
Au+
CN-
Electroplating
Au plating a Cu pennyElectroplating is the process of reducing a metal on to the surface of anotherElectrolyte: Must contain the ion of the metal that platesCathode: The metal to be covered with a new metalAnode: Metal to be plated on top the other metal
DC Power- +
DC Power- +
Au
+OxidationAnodeAu(s) → Au+ + 1e-
e--ReductionCathodeAu+ + e- → Au(s)
CuCu
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AuCN
-ve+ve
stainless steel or Au
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Au plated
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Copper Ring Gold Plated
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Tanya’s Ring Gold Plated
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Ag+
NO3-
Electroplating
Ag plating a Loonie
DC Power- +
DC Power- +
Ag
+OxidationAnodeAg(s) → Ag+ + 1e-
e--ReductionCathodeAg+ + e- → Ag(s)
$1
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Electrorefinning Lead Trail, B.C.Teck 16 mines in BCMajor 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 PbImpure metal is oxidized at the anode and pure metal is reduced at the cathode.This is the same as electroplating.
DC Power- +
DC Power- +
Pb2+
NO3-
-ReductionCathode
Pb2+ + 2e- → Pb(s)
Cathode: Pure Pb
Anode: Impure Pb
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The impurities in Pb are:AuAgZn
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Zn oxidizes
Ag does not oxidize
Pb oxidizes
Au does not oxidizeAt the Anode
The voltage is controlled so that:
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Pb2+ reduces
At the Cathode
Zn2+ does not reduce
The voltage is controlled so that:
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The Electrorefinning of Lead Electrorefining is the process of purifying a metal by electrolysis.The electrolyte must contain PbImpure metal is oxidized at the anode and pure metal is reduced at the cathode.This is the same as electroplating.
DC Power- +
DC Power- +
Pb2+
NO3-
-ReductionCathode
Pb2+ + 2e- → Pb(s)
Cathode: Pure Pb Anode: Impure Pb
+OxidationAnodeZn(s) → Zn2+ + 2e-
Pb(s) → Pb2+ + 2e-
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