Transcript Introduction to Redox

Electrochemistry
Lesson 1
Introduction
Electrochemistry
Is the study of reactions that gain or lose electrons.
Electrochemistry
Is the study of reactions that gain or lose electrons.
In this unit we will study:
Battery Reactions
Corrosion
Preventing Corrosion
Combustion
Electroplating
Refining Metals
Oxidation means loss of electrons
LEO
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
Na
→
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
Na
metal
→
ion
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
Na
metal
→
Na+
ion
Balance charge
Add electron to
most positive side
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
Na
metal
→
Na+
ion
Balance charge
Add electron to
most positive side
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
0
Na
metal
+1
→
Na+
ion
Balance charge
Add electron to
most positive side
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
0
Na
metal
0
→
Na+ +
ion
1eBalance charge
Add electron to
most positive side
Oxidation- electrons are on the right
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
Al
→
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
Al
metal
→
ion
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
Al
metal
→
Al3+
ion
Balance charge
Add electrons to
most positive side
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
Al
metal
→
Al3+
ion
Balance charge
Add electrons to
most positive side
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
0
Al
metal
+3
→
Al3+
ion
Balance charge
Add electrons to
most positive side
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
0
Al
metal
0
→
Al3+ +
ion
3eBalance charge
Add electrons to
most positive side
Oxidation- electrons are on the right
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
O2-
→
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
O2-
anion
→
atom
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
O2-
anion
→
O2
atom
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
O2-
→
O2
Balance for numbers
anion
atom
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
2O2- →
O2
Balance for numbers
anion
atom
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
2O2- →
O2
Balance for numbers
anion
atom
Balance charge
Add electrons to
most positive side
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
-4
0
2O2- →
O2
Balance for numbers
anion
atom
Balance charge
Add electrons to
most positive side
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
-4
2O2- →
-4
O2
+
4eBalance for numbers
anion
atom
Balance charge
Add electrons to
most positive side
Oxidation means loss of electrons
LEO
LossElectronsOxidation
Oxidation Half Reactions
show how Metals or Anions lose electrons
2O2- →
O2
+
4eBalance for numbers
anion
atom
Oxidation- electrons are on the right
Balance charge
Add electrons to
most positive side
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
Ga3+
→
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
Ga3+
cation
→
atom
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
Ga3+
cation
→
Ga
atom
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
+3
Ga3+
cation
0
→
Ga
atom
Balance charge
Add electrons to
most positive side
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
0
Ga3+ + 3e- →
cation
0
Ga
atom
Reduction- electrons are on the left
Balance charge
Add electrons to
most positive side
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
N2
→
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
N2
→
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
N2
→
N3-
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
N2
→
2N3-
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
N2
+ 6e- →
2N3-
Reduction means gain of electrons
GER
GainElectronsReduction
Reduction Half Reactions
show how Nonmetals or Cations gain electrons
N2
+ 6e- →
2N3-
Reduction- electrons are on the left
Balance each simple half reaction
1.
Ca
→
2.
F2
→
3.
O2
→
4.
Ga
→
5.
Br -
→
6.
Li+
→
Balance each simple half reaction
1.
Ca
→
2.
F2
+ 2e- →
2F-
3.
O2
+ 4e- →
2O2-
4.
Ga
→
5.
Br -
→
6.
Li+
→
Ca2+ +
2e-
Balance each simple half reaction
1.
Ca
→
2.
F2
+ 2e- →
2F-
3.
O2
+ 4e- →
2O2-
4.
Ga
→
Ga3+ +
5.
2Br -
→
Br2 + 2e-
6.
Li+
e-
→
+
Ca2+ +
Li
2e-
3e-
Balance each simple half reaction
1.
Ca
→
2.
F2
+ 2e- →
2F-
reduction
3.
O2
+ 4e- →
2O2-
reduction
4.
Ga
→
Ga3+ +
5.
2Br -
→
Br2 + 2e-
oxidation
6.
Li+
e-
→
reduction
+
Ca2+ +
Li
2e-
3e-
oxidation
oxidation
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
Al
→
Al3+ +
3e-
oxidation
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
Al
→
Al3+ +
Zn2+
Use metals/cations
3e-
oxidation
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
Al
→
Al3+ +
Zn2+ +
2e-
→
3e-
oxidation
Zn
reduction
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
2(Al →
Al3+ +
3(Zn2++
2e-
Balance electrons
→
3e-)
oxidation
Zn)
reduction
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
2(Al →
Al3+ +
3(Zn2++
2e-
→
3e-)
oxidation
Zn)
reduction
2Al + 3Zn2+ + 6e- → 2Al3+ + 3Zn + 6e- redox
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
2(Al →
Al3+ +
3(Zn2++
2e-
→
3e-)
oxidation
Zn)
reduction
2Al + 3Zn2+ + 6e- → 2Al3+ + 3Zn + 6e- redox
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
2(Al →
Al3+ +
3(Zn2++
2e-
→
3e-)
oxidation
Zn)
reduction
2Al + 3Zn2+ → 2Al3+ + 3Zn
redox
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
2(Al →
Al3+ +
3(Zn2++
2e-
→
3e-)
oxidation
Zn)
reduction
2Al + 3Zn2+ → 2Al3+ + 3Zn
Check charge
redox
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
2(Al →
Al3+ +
3(Zn2++
2e-
→
3e-)
oxidation
Zn)
reduction
2Al + 3Zn2+ → 2Al3+ + 3Zn
+6
Check charge
+6
redox
Redox Reactions
Both oxidation and reduction must occur.
The number of electrons gained must be equal to the number
of electrons lost.
It is simpler to write the net ionic equation.
1.
Al
+
Zn(NO3)2
2(Al →
Al3+ +
3(Zn2++
2e-
→
3e-)
oxidation
Zn)
reduction
2Al + 3Zn2+ → 2Al3+ + 3Zn
+6
Check charge
redox
+6
Same!
2.
Cl2
+
Na
2.
Cl2
+
Na
Cl2
+
2e-
→
2Cl- reduction
2.
Cl2
+
Na
Cl2
+
2e-
→
2Cl- reduction
Na
→
Na+
+
1e-
oxidation
2.
Cl2
+
Na
Cl2
+
2e-
→
2Cl- reduction
Na+
+
1e-)
2(Na →
oxidation
2.
Cl2
+
Na
Cl2
+
2e-
→
2Cl-
reduction
Na+
+
1e-)
oxidation
2(Na →
Cl2 + 2Na →
0
2Cl-
+
0
2Na+
redox
Oxidizing Agents
Oxidizing Agents cause oxidation by undergoing reduction.
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons.
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Cl2
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Cl2
Ca2+
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Cl2
Ca2+
F2
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Cl2
Ca2+
F2
Na+
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Cl2
Ca2+
Cl2
+
Na+
F2
2e-
→
2Cl-
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Cl2
Ca2+
Na+
Cl2
+
2e-
→
2Cl-
Ca2+
+
2e-
→
Ca
F2
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Cl2
Ca2+
Na+
F2
Both can gain electrons
Cl2
+
2e-
→
2Cl-
Ca2+
+
2e-
→
Ca
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Cl2
Ca2+
Na+
F2
Both can gain electrons
Cl2
+
2e-
→
2Cl-
Ca2+
+
2e-
→
Ca
Oxidizing Agents cause oxidation by undergoing reduction.
They gain electrons. Nonmetals and cations are oxidizing
agents because they gain electrons.
Cl2
Ca2+
Na+
F2
Both can gain electrons
Cl2
+
2e-
→
2Cl-
Ca2+
+
2e-
→
Ca
Reducing Agents
Reducing Agents cause reduction by undergoing oxidation.
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons.
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons. Metals and anions are reducing agents
because they lose electrons.
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons. Metals and anions are reducing agents
because they lose electrons.
N3-
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons. Metals and anions are reducing agents
because they lose electrons.
N3-
Al
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons. Metals and anions are reducing agents
because they lose electrons.
N3-
Al
O2-
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons. Metals and anions are reducing agents
because they lose electrons.
N3-
Al
O2-
Li
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons. Metals and anions are reducing agents
because they lose electrons.
N3-
Al
O2-
2N3-
→
N2
+
6e-
Al
→
Al3+ +
3e-
Li
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons. Metals and anions are reducing agents
because they lose electrons.
N3-
O2-
Al
Li
Both can lose electrons
2N3-
→
N2
+
6e-
Al
→
Al3+ +
3e-
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons. Metals and anions are reducing agents
because they lose electrons.
N3-
O2-
Al
Li
Both can lose electrons
2N3-
→
N2
+
6e-
Al
→
Al3+ +
3e-
Reducing Agents cause reduction by undergoing oxidation.
They lose electrons. Metals and anions are reducing agents
because they lose electrons.
N3-
O2-
Al
Li
Both can lose electrons
2N3-
→
N2
+
6e-
Al
→
Al3+ +
3e-
You need to be able to tell an oxidizing agent from a
reducing agent.
You need to be able to tell an oxidizing agent from a
reducing agent.
Circle each oxidizing agent.
You need to be able to tell an oxidizing agent from a
reducing agent.
Circle each oxidizing agent.
They can reduce or gain electrons
You need to be able to tell an oxidizing agent from a
reducing agent.
Circle each oxidizing agent.
They can reduce or gain electrons
Ga
Rb+
I-
P4
Fe
Co2+
S
I2
Cu
Pb2+
Li
Br-
You need to be able to tell an oxidizing agent from a
reducing agent.
Circle each oxidizing agent.
They can reduce or gain electrons
Ga
Rb+
I-
P4
Fe
Co2+
S
I2
Cu
Pb2+
Li
Br-
You need to be able to tell an oxidizing agent from a
reducing agent.
Circle each oxidizing agent.
They can reduce or gain electrons
Ga
Rb+
I-
P4
Fe
Co2+
S
I2
Cu
Pb2+
Li
Br-
You need to be able to tell an oxidizing agent from a
reducing agent.
Circle each oxidizing agent.
They can reduce or gain electrons
Ga
Rb+
I-
P4
Fe
Co2+
S
I2
Cu
Pb2+
Li
Br-
You need to be able to tell an oxidizing agent from a
reducing agent.
Circle each oxidizing agent.
They can reduce or gain electrons
Ga
Rb+
I-
P4
Fe
Co2+
S
I2
Cu
Pb2+
Li
Br-
You need to be able to tell an oxidizing agent from a
reducing agent.
Circle each oxidizing agent.
They can reduce or gain electrons
Ga
Rb+
I-
P4
Fe
Co2+
S
I2
Cu
Pb2+
Li
Br-
You need to be able to tell an oxidizing agent from a
reducing agent.
Circle each oxidizing agent.
They can reduce or gain electrons
Ga
Rb+
I-
P4
Fe
Co2+
S
I2
Cu
Pb2+
Li
Br-
Label each reactant as an oxidizing or reducing agent.
2Ag+
+
Pb
→
2Ag
+
Pb2+
Label each reactant as an oxidizing or reducing agent.
2Ag+
Reduction
+
Pb
→
2Ag
+
Pb2+
Label each reactant as an oxidizing or reducing agent.
2Ag+
Reduction
+
Pb
Oxidation
→
2Ag
+
Pb2+
Label each reactant as an oxidizing or reducing agent.
2Ag+
Reduction
Ox Agent
+
Pb
Oxidation
→
2Ag
+
Pb2+
Label each reactant as an oxidizing or reducing agent.
2Ag+
+
Pb
Reduction
Oxidation
Ox Agent
Red Agent
→
2Ag
+
Pb2+
Label each reactant as an oxidizing or reducing agent.
6I-
+
2Al3+
→
3I2
+
Al
Label each reactant as an oxidizing or reducing agent.
6IOxidation
+
2Al3+
→
3I2
+
Al
Label each reactant as an oxidizing or reducing agent.
6IOxidation
+
2Al3+
Reduction
→
3I2
+
Al
Label each reactant as an oxidizing or reducing agent.
6IOxidation
Red Agent
+
2Al3+
Reduction
→
3I2
+
Al
Label each reactant as an oxidizing or reducing agent.
6I-
+
2Al3+
Oxidation
Reduction
Red Agent
Ox Agent
→
3I2
+
Al