Electrolysis Electrolysis describes what happens in an electrolytic cell and means to use...
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Transcript of Electrolysis Electrolysis describes what happens in an electrolytic cell and means to use...
Electrolysis
Electrolysis describes what happens in an electrolytic cell andmeans to use electricity to make chemicals.
Pb Al Zn Na K Li H2 Cl2 F2
I2 O2 are all made by electrolysis
When metals are made by electrolysis it is sometimes called electrowinning as the metal is won from the ion as it is reduced.
Pb2+ + 2e- → Pb(s)
2Cl- → Cl2(g) + 2e-
Electrolysis of Aluminum Alcan Kitimat B.C.
Name of the Ore used: 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
DC Power - +
Al2O3(l)
CC
DC Power - +
Al2O3(l)
CC
Al3+
O2-
DC Power - +
Al2O3(l)
CC
Al3+
O2-
-
reduction
DC Power - +
Al2O3(l)
CC
Al3+
O2-
-
Reduction
+
Oxidation
DC Power - +
Al2O3(l)
CC
Al3+
O2-
-
Reduction
Cathode
+
Oxidation
Anode
DC Power - +
Al2O3(l)
CC
Al3+
O2-
-
Reduction
Cathode
+
Oxidation
Anode
DC Power - +
Al2O3(l)
CC
Al3+
O2-
-
Reduction
Cathode
Al3+ + 3e- → Al(s)
+
Oxidation
Anode
DC Power - +
Al2O3(l)
CC
Al3+
O2-
-
Reduction
Cathode
Al3+ + 3e- → Al(s)
+
Oxidation
Anode
2O2- → O2 + 4e-
DC Power - +
Al2O3(l)
CC
Al3+
O2-
-
Reduction
Cathode
Al3+ + 3e- → Al(s)
+
Oxidation
Anode
2O2- → O2 + 4e-
Liquid Al floats to the top and is removed.
DC Power - +
Al2O3(l)
CC
Al3+
O2-
-
Reduction
Cathode
Al3+ + 3e- → Al(s)
+
Oxidation
Anode
2O2- → O2 + 4e-
Liquid Al floats to the top and is removed.
Oxygen gas
Non-Inert ElectrodesYou must understand that a non-inert Anode might oxidize.
K2SO4(aq)
DC Power
- +
CuCu
Non-Inert ElectrodesYou must understand that a non-inert Anode might oxidize.The Cathode will stay inert because it already is reduced.
K2SO4(aq)
DC Power
- +
CuCu
Non-Inert ElectrodesYou must understand that a non-inert Anode might oxidize.The Cathode will stay inert because it already is reduced.
DC Power
- +
K2SO4(aq)
CuCu
2K+
SO42-
H2O
Non-Inert ElectrodesYou must understand that a non-inert Anode might oxidize.The Cathode will stay inert because it already is reduced.
DC Power
- +
K2SO4(aq)
CuCu
2K+
SO42-
H2O
-
Cathode
Reduction
Non-Inert ElectrodesYou must understand that a non-inert Anode might oxidize.The Cathode will stay inert because it already is reduced.
DC Power
- +
K2SO4(aq)
CuCu
-
Cathode
Reduction
2H2O + 2e-→H2 +2OH-
-0.41 v
2K+
SO42-
H2O
Non-Inert ElectrodesYou must understand that a non-inert Anode might oxidize.The Cathode will stay inert because it already is reduced.
DC Power
- +
K2SO4(aq)
CuCu
-
Cathode
Reduction
2H2O + 2e-→H2 +2OH-
-0.41 v
+
Anode
Oxidation
2K+
SO42-
H2O
You must look at the possible oxidation of:
H2O SO4
2- CuCheck out the reduction chart!
S2O82- + 2e- → 2SO4
2- 2.01 v
1/2O2 + 2H+(10-7M) → H20 0.82 v
Cu+ + 1e- → Cu(s) 0.52 v
Cu2+ + 2e- → Cu(s)* 0.34 v* Strongest Reducing Agent
Non-Inert Electrodes
You must understand that a non-inert Anode might oxidize.The Cathode will stay inert because it already is reduced.
DC Power
- +
K2SO4(aq)
CuCu
2K+
SO42-
-
Cathode
Reduction
2H2O + 2e-→H2 +2OH-
-0.41 v
+
Anode
Oxidation
Cu(s) → Cu2++2e-
-0.34 v
Non-Inert Electrodes
You must understand that a non-inert Anode might oxidize.The Cathode will stay inert because it already is reduced.
DC Power
- +
K2SO4(aq)
CuCu
2K+
SO42-
-
Cathode
Reduction
2H2O +2e→H2(g)+2OH-
-0.41 v
+
Anode
Oxidation
Cu(s) → Cu2++2e-
-0.34 v
2H2O + Cu(s) → Cu2++ H2 +2OH- E0 = -0.75 v MTV = +0.75 v
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
Pourous membrane
Or it might look like this
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
H+
H2O
Cl-
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
H+
H2O
Cl-
Is this cell electrolytic or electrochemical?
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
H+
H2O
Cl-
Electrochemical- There is no power supplyCu is higher and the cathodeZn is lower and the anode.
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
H+
H2O
Cl-
Electrochemical- Cu is higher and the cathodeZn is lower and the anode.
CathodeReductionNo Cu2+ to reduce!
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
H+
H2O
Cl-
Electrochemical- Cu is higher and the cathodeZn is lower and the anode.
CathodeReduction2H+ + 2e- → H2(g)
0.00 v
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
H+
H2O
Cl-
Electrochemical- Cu is higher and the cathodeZn is lower and the anode.
CathodeReduction2H+ + 2e- → H2(g)
0.00 v
AnodeOxidationWhat oxidizes?ZnH2OCl-
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
H+
H2O
Cl-
Electrochemical- Cu is higher and the cathodeZn is lower and the anode.
CathodeReduction2H+ + 2e- → H2(g)
0.00 v
AnodeOxidationZn → Zn2+ + 2e-
0.76 v
HCl(aq)
ZnCu
0.76 v Voltmeter
Analyze This Cell
H+
H2O
Cl-
2H+ + Zn(s) → Zn2+ + H2(g) E0 = 0.76 v
CathodeReduction2H+ + 2e- → H2(g)
0.00 v
AnodeOxidationZn(s) → Zn2+ + 2e-
0.76 v
Electroplating
Electroplating is the process of reducing a metal on to the surface of another. Anode: Metal to be plated on top the other metal Cathode: The other metal to be covered with the new metal Electrolyte: Must contain the ion of the metal that plates Ni plating a Cu penny Anode: Cathode: Electrolyte:
DC Power
Electroplating
Electroplating is the process of reducing a metal on to the surface of another. Anode: Metal to be plated on top the other metal Cathode: The other metal to be covered with the new metal Electrolyte: Must contain the ion of the metal that plates Ni plating a Cu penny Anode: Ni Cathode: Electrolyte:
DC Power
Ni
Electroplating
Electroplating is the process of reducing a metal on to the surface of another. Anode: Metal to be plated on top the other metal Cathode: The other metal to be covered with the new metal Electrolyte: Must contain the ion of the metal that plates Ni plating a Cu penny Anode: Ni Cathode: Cu Electrolyte:
DC Power
Cu
Ni
Electroplating
Electroplating is the process of reducing a metal on to the surface of another. Anode: Metal to be plated on top the other metal Cathode: The other metal to be covered with the new metal Electrolyte: Must contain the ion of the metal that plates Ni plating a Cu penny Anode: Ni Cathode: Cu Electrolyte: Ni(NO3)2
DC Power
Cu
Ni
Ni2+
NO3-
Electroplating
Electroplating is the process of reducing a metal on to the surface of another. Anode: Metal to be plated on top the other metal Cathode: The other metal to be covered with the new metal Electrolyte: Must contain the ion of the metal that plates Ni plating a Cu penny Anode: Ni Cathode: Cu Electrolyte: Ni(NO3)2
DC Power- +
Cu
Ni
Ni2+
NO3-
Electroplating
Electroplating is the process of reducing a metal on to the surface of another. Anode: Metal to be plated on top the other metal Cathode: The other metal to be covered with the new metal Electrolyte: Must contain the ion of the metal that plates Ni plating a Cu penny Anode: Ni Cathode: Cu Electrolyte: Ni(NO3)2
DC Power- +
Cu
Ni
Ni2+
NO3-
-ReductionCathode
Electroplating
Electroplating is the process of reducing a metal on to the surface of another. Anode: Metal to be plated on top the other metal Cathode: The other metal to be covered with the new metal Must be negative!Electrolyte: Must contain the ion of the metal that plates Ni plating a Cu penny Anode: Ni Cathode: Cu Electrolyte: Ni(NO3)2
DC Power- +
Cu
Ni
Ni2+
NO3-
-ReductionCathodeNi2+ + 2e- → Ni(s)
Electroplating
Electroplating is the process of reducing a metal on to the surface of another. Anode: Metal to be plated on top the other metal Cathode: The other metal to be covered with the new metal Electrolyte: Must contain the ion of the metal that plates Ni plating a Cu penny Anode: Ni Cathode: Cu Electrolyte: Ni(NO3)2
DC Power- +
Cu
Ni
Ni2+
NO3-
-ReductionCathodeNi2+ + 2e- → Ni(s)
+OxidationAnodeNi(s) → Ni2+ + 2e-
e-
Silver plating a Loonie Anode: Cathode:
Electrolyte:
DC Power
$1
Silver plating a Loonie Anode: Ag Cathode:
Electrolyte:
DC Power
$1
Ag
Silver plating a Loonie Anode: Ag Cathode: Loonie
Electrolyte:
DC Power- +
$1
Ag
Loonie
Silver plating a Loonie Anode: Ag Cathode: Loonie
Electrolyte: AgNO3
DC Power- +
$1
Ag
Loonie
Ag+
NO3-
Silver plating a Loonie Anode: Ag Cathode: Loonie
Electrolyte: AgNO3
DC Power- +
$1
Ag
Loonie
Ag+
NO3-
-ReductionCathodeAg+ + 1e- → Ag(s)
+OxidationAnodeAg(s) → Ag+ + 1e-
e- e-
Electrorefining Electrorefining is the process of purifying a metal by electrolysis.Impure metal is oxidized at the anode and pure metal is reduced at the cathode.This is the same as electroplating. The Electrorefinning of Lead Cominco Trail, B.C.
Cathode: Anode:
Electrolyte:
DC Power- +
Electrorefining Electrorefining is the process of purifying a metal by electrolysis.Impure metal is oxidized at the anode and pure metal is reduced at the cathode.This is the same as electroplating. The Electrorefinning of Lead Cominco Trail, B.C.
Cathode: Pure Pb Anode:
Electrolyte:
DC Power- +
Electrorefining Electrorefining is the process of purifying a metal by electrolysis.Impure metal is oxidized at the anode and pure metal is reduced at the cathode.This is the same as electroplating. The Electrorefinning of Lead Cominco Trail, B.C.
Cathode: Pure Pb Anode: Impure Pb
Electrolyte:
DC Power- +
Electrorefining Electrorefining is the process of purifying a metal by electrolysis.Impure metal is oxidized at the anode and pure metal is reduced at the cathode.This is the same as electroplating. The Electrorefinning of Lead Cominco Trail, B.C.
Cathode: Pure Pb Anode: Impure Pb
Electrolyte: Pb(NO3)2
DC Power- +
Pb2+
NO3-
Electrorefining Electrorefining is the process of purifying a metal by electrolysis.Impure metal is oxidized at the anode and pure metal is reduced at the cathode.This is the same as electroplating. The Electrorefinning of Lead Cominco Trail, B.C.
Cathode: Pure Pb Anode: Impure Pb
Electrolyte: Pb(NO3)2
DC Power- +
Pb2+
NO3-
-ReductionCathode
Pb2+ + 2e- → Pb(s)
Electrorefining Electrorefining is the process of purifying a metal by electrolysis.Impure metal is oxidized at the anode and pure metal is reduced at the cathode.This is the same as electroplating. The Electrorefinning of Lead Cominco Trail, B.C.
Cathode: Pure Pb Anode: Impure Pb
Electrolyte: Pb(NO3)2
DC Power- +
Zn2+
Pb2+
NO3-
-ReductionCathode
Pb2+ + 2e- → Pb(s)
+OxidationAnode
Pb(s) → Pb2+ + 2e- Au Cu