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Lecture 5 Reduction-Oxidation Reactions Redox
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Lecture 5Lecture 5
Reduction-Oxidation Reactions
Redox
Reduction-Oxidation Reactions
Redox
What is a redox reaction?What is a redox reaction?
==> When in the reaction, electrons are being transferred from one substance to another.
What has to happen? Something has to be gaining e- (becoming negative) and something has to be losing e- (becoming positive).
==> When in the reaction, electrons are being transferred from one substance to another.
What has to happen? Something has to be gaining e- (becoming negative) and something has to be losing e- (becoming positive).
How do you tell?Need to assign each individual element an oxidation number.
How do you tell?Need to assign each individual element an oxidation number.
Rules:1) When atoms are by themselves (including diatomics) they have an
oxidation # of 0. Ex: Na, N2, Cl2, O2, Fe, Mg
Rules:1) When atoms are by themselves (including diatomics) they have an
oxidation # of 0. Ex: Na, N2, Cl2, O2, Fe, Mg
How do you tell?Need to assign each individual element an oxidation number.
How do you tell?Need to assign each individual element an oxidation number.
Rules:1) When atoms are by themselves (including diatomics) they have
an oxidation # of 0.
2) Monatomic ions have an oxidation # equaling their charge.
Ex: Cl-1, Na+1, N-3, O-2, Fe+3, Mg+2
Rules:1) When atoms are by themselves (including diatomics) they have
an oxidation # of 0.
2) Monatomic ions have an oxidation # equaling their charge.
Ex: Cl-1, Na+1, N-3, O-2, Fe+3, Mg+2
How do you tell?Need to assign each individual element an oxidation number.
How do you tell?Need to assign each individual element an oxidation number.
Rules:1) When atoms are by themselves (including diatomics) they have
an oxidation # of 0.
2) Monatomic ions have an oxidation # equaling their charge.
3) Compounds are neutral. Sum of oxidation # must be 0
Rules:1) When atoms are by themselves (including diatomics) they have
an oxidation # of 0.
2) Monatomic ions have an oxidation # equaling their charge.
3) Compounds are neutral. Sum of oxidation # must be 0
How do you tell?Need to assign each individual element an oxidation number.
How do you tell?Need to assign each individual element an oxidation number.
Rules:1) When atoms are by themselves (including diatomics) they have
an oxidation # of 0.
2) Monatomic ions have an oxidation # equaling their charge.
3) Compounds are neutral. Sum of oxidation # must be 0
4) Polyatomic ions must have the sum of oxidation # equal their charge.
Rules:1) When atoms are by themselves (including diatomics) they have
an oxidation # of 0.
2) Monatomic ions have an oxidation # equaling their charge.
3) Compounds are neutral. Sum of oxidation # must be 0
4) Polyatomic ions must have the sum of oxidation # equal their charge.
How do you tell?Need to assign each individual element an oxidation number.
How do you tell?Need to assign each individual element an oxidation number.
Rules:5) Oxygen in a compound usually has a charge of -2.
Exception: peroxide where it equals -1
Rules:5) Oxygen in a compound usually has a charge of -2.
Exception: peroxide where it equals -1
How do you tell?Need to assign each individual element an oxidation number.
How do you tell?Need to assign each individual element an oxidation number.
Rules:5) Oxygen in a compound usually has a charge of -2.
Exception: peroxide where it equals -1
6) In covalent compounds, hydrogen is +1.
Rules:5) Oxygen in a compound usually has a charge of -2.
Exception: peroxide where it equals -1
6) In covalent compounds, hydrogen is +1.
How do you tell?Need to assign each individual element an oxidation number.
How do you tell?Need to assign each individual element an oxidation number.
Rules:5) Oxygen in a compound usually has a charge of -2.
Exception: peroxide where it equals -1
6) In covalent compounds, hydrogen is +1.
Application: NO2 NO NO3l- HC2H3O2 SO4
-2
Rules:5) Oxygen in a compound usually has a charge of -2.
Exception: peroxide where it equals -1
6) In covalent compounds, hydrogen is +1.
Application: NO2 NO NO3l- HC2H3O2 SO4
-2
How do you tell?Need to assign each individual element an oxidation number.
How do you tell?Need to assign each individual element an oxidation number.
Rules:5) Oxygen in a compound usually has a charge of -2.
Exception: peroxide where it equals -1
6) In covalent compounds, hydrogen is +1.
7) If else fails use the periodic table.
Group 1 = 1+
Group 2 = 2+
Group 7 = 1-
Rules:5) Oxygen in a compound usually has a charge of -2.
Exception: peroxide where it equals -1
6) In covalent compounds, hydrogen is +1.
7) If else fails use the periodic table.
Group 1 = 1+
Group 2 = 2+
Group 7 = 1-
More PracticeMore Practice
Try these brain busters! KMnO4
H2CO3
PH3
MgC4H4O6
Try these brain busters! KMnO4
H2CO3
PH3
MgC4H4O6
Remember!Remember! Oxidation can be all sorts of numbers, even
fractions :]
Fe304
Oxygen is -2, so what does Fe have to be?
Oxidation can be all sorts of numbers, even fractions :]
Fe304
Oxygen is -2, so what does Fe have to be?
Remember!Remember!
Oxidation can be all sorts of numbers even fractions :]
Fe304
Oxygen is -2 so what does Fe have to be?
Iron is + 8/3
Oxidation can be all sorts of numbers even fractions :]
Fe304
Oxygen is -2 so what does Fe have to be?
Iron is + 8/3
Characteristics of Redox reactions:Characteristics of Redox reactions:
1) Oxidation-substance losing electrons 1) Oxidation-substance losing electrons
Characteristics of Redox reactions:Characteristics of Redox reactions:
1) Oxidation-substance losing electrons 2) Reduction-substance gaining electrons
1) Oxidation-substance losing electrons 2) Reduction-substance gaining electrons
Characteristics of Redox reactions:Characteristics of Redox reactions:
1) Oxidation-substance losing electrons 2) Reduction-substance gaining electrons
1) Oxidation-substance losing electrons 2) Reduction-substance gaining electrons
Lots of Ways to Remember!Lots of Ways to Remember!
Oil Rig
O I L R I G
Oil Rig
O I L R I G
Lots of Ways to Remember!Lots of Ways to Remember!
Leo goes Ger
L E O goes G E R
Leo goes Ger
L E O goes G E R
Lots of Ways to Remember!Lots of Ways to Remember!
Olé!
O L E !
Olé!
O L E !
2 Na(s) + Cl2(g) ==> 2NaCl(s)2 Na(s) + Cl2(g) ==> 2NaCl(s)
What’s being oxidized? Reduced? What’s being oxidized? Reduced?
0 0 1+ 1-2 Na(s) + Cl2(g) ==> 2NaCl(s) 0 0 1+ 1-2 Na(s) + Cl2(g) ==> 2NaCl(s) What’s being oxidized? Reduced?
Oxidized: Na
Reduced: Cl2
What’s being oxidized? Reduced?
Oxidized: Na
Reduced: Cl2
