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Application of Electrolytic Cells Lesson 11. 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 H 2 Cl 2 F 2 I 2 O 2 Pb 2+ + 2e - → Pb (s)
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Application of Electrolytic Cells Lesson 11
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
Making Aluminum by Electrolysis Alcan (70,000 employees in 55 countries) Kitimat B.C. 2.7 MT 7 % world production
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 istoohot! Cryolite is added Lowers the melting point to 1000 0C
Reduction of water You cannot reduce Aluminum in water! It must be molten!
Liquid Al floats to the top and is removed DC Power - + 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
Electroplating Auplatinga Cu penny Electroplatingis the process of reducing a metalon to the surface of another Electrolyte: Must contain the ion of the metal that plates Cathode: The metalto 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
+ve -ve stainless steel or Au AuCN
Copper Ring Gold Plated
Electroplating Agplatinga Loonie DC Power - + e- - Reduction Cathode Ag+ + e-→ Ag(s) Ag + Oxidation Anode Ag(s) → Ag+ + 1e- Ag+ NO3- $1 $1
Electrorefinning Lead Trail, B.C. Teck 16 mines in BC Major World Producer of Zn, Cu, Pb, and Coal
The Electrorefinning of Lead Electrorefining is the process of purifying a metalby electrolysis. The electrolyte must contain Pb Impuremetal is oxidizedat theanodeand 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-
The impurities in Pb are: Au Ag Zn
At the Anode Au does not oxidize The voltage is controlled so that: Ag does not oxidize Pb oxidizes Zn oxidizes
At the Cathode The voltage is controlled so that: Pb2+ reduces Zn2+ does not reduce
The Electrorefinning of Lead Electrorefining is the process of purifying a metalby electrolysis. The electrolyte must contain Pb Impuremetal is oxidizedat theanodeand 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
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