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Transcript of Introduction to Oxidation and Reduction Copyright © The McGraw-Hill Companies, Inc. Permission...
Introduction to Oxidation and Reduction
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
IB Chemistry Text
Green and Damji
TEXT 9.1 & 9.2
Types of Chemical Reactions ?
type of
reaction ?
1. Mg(s) + 2 HCl (aq) MgCl2 (aq) + H2 (g)
2. Pb(NO3)2 (aq) + 2 NaI (aq) PbI2 (s) + 2 NaNO3 (aq)
3. 2 H2O2 (aq) O2 (g) + 2 H2O (g)
4. 2 O2 (g) + CH4 (g) CO2 (g) + 2 H2O (g)
5. 2 H2 O (g) O2 (g) + H2(g)
another way to classify Types of Chemical Reactions
A. Acid Base Reactions
B. Precipitation Reactions
C. Redox Reactions
CaO (s) + 2 HCl (aq) CaCl2 (aq) + H2O (l)
H3PO4 (aq) + 3 NaOH (aq) Na3PO4 (aq) + 3 H2O (l)
Pb(NO3)2 (aq) + 2NaI (aq) PbI2 (s) + 2NaNO3 (aq)
which can be shortened to…Pb2+ + 2I- PbI2 (s)
2 Zn (s) + I2 (s) ZnI2 (aq)
2 Zn (s) + I2 (s) Zn2+ (aq) + 2 I- (aq)
Ca2+ + CO32- CaCO3
NH3 + H+ NH4+
Zn + 2HCl ZnCl2 + H2
Ca + F2 CaF2
________________
________________
________________
________________
Classify the following reactions as AB/PPT/RedOx
4.4
Oxidation-Reduction Reactions(electron transfer reactions)
2Mg + O2 2MgO
4.4
What is happening in this reaction? oxidation – loss of electrons: reduction – gain of electrons:
Helpful MneumonicsLEO the lion goes GER
Loss of Electrons is Oxidation
Gain of Electrons is Reduction
OIL RIG
Oxidation is the Loss of electrons
Reduction is the Gain of electrons
Oxidation numberThe charge the atom would have in a molecule (or anionic compound) if electrons were completely transferred to the more electronegative element.
1. Free elements (uncombined state) have an oxidation number of zero.
Na, Be, K, Pb, H2, O2, P4 =
2. In monatomic ions, the oxidation number is equal to the charge on the ion.
Li+, Li = ; Fe3+, Fe = ; O2-, O =
3. The oxidation number of oxygen is usually . In H2O2
and O22- it is .
4.4
4. The oxidation number of hydrogen is____except when it is bonded to metals in binary compounds. In these cases, its oxidation number is____.
6. The sum of the oxidation numbers of all the atoms in a molecule or ion is equal to the charge on the molecule or ion.
5. Group 1 metals are____, Group 2 metals are____and fluorine is always____.
HCO3-
O = ____ H = ____
3x(-2) + 1 + ? = -1
C = ____
Oxidation numbers of all the elements in HCO3
- ?
4.4
7. Oxidation numbers do not have to be integers. Oxidation number of oxygen in the superoxide ion, O2
-, is ____.
The oxidation numbers of elements in their compounds
4.4
The periodic table in your planner
includes the most common oxidation
numbers!
Na I O3
Na = ____ O = ____
3x(____) + ____ + ? = 0
I = ____
I F7
F = ____
7x(____) + ? = 0
I = ____
K2 Cr2 O7
O = ____ K = ____
7x(__) + 2x(__) + 2x(?) = 0
Cr = ____
What are the oxidation numbers of all the elements in the following compounds ?
4.4
More to know…An increase in oxidation number is oxidation.
A decrease in oxidation number is reduction.
The substance that is oxidized (loses e-; ox # increases)
is called the reducing agent.
The substance that is reduced (gains e-; ox # decreases)
is called the reducing agent.
4.4
Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
ox:
red:
---------------------------------------
ttl:
____ is oxidized - is reducing agent
____ is reduced - is oxidizing agent
4.4
Copper wire reacts with silver nitrate to form silver metal.What is the oxidizing agent in the reaction?
ox:
red:
---------------------------------------
ttl:
____ is oxidized - is reducing agent
____ is reduced - is oxidizing agent
Types of Oxidation-Reduction Reactions
Combination Reaction (aka Synthesis)
A + B C
2Al + 3Br2 2AlBr3
Decomposition Reaction
2KClO3 2KCl + 3O2
C A + B
0 0 +3 -1
+1 +5 -2 +1 -1 0
4.4
Types of Oxidation-Reduction Reactions
Combustion Reaction
A + O2 B
S + O2 SO2
0 0 +4 -2
4.4
2Mg + O2 2MgO0 0 +2 -2
Single Displacement Reaction
A + BC AC + B
Sr + 2H2O Sr(OH)2 + H2
TiCl4 + 2Mg Ti + 2MgCl2
Cl2 + 2KBr 2KCl + Br2
Hydrogen Displacement
Metal Displacement
Halogen Displacement
Types of Oxidation-Reduction Reactions
4.4
0 +1 +2 0
0+4 0 +2
0 -1 -1 0
Disproportionation Reaction
Cl2 + 2 OH- ClO- + Cl- + H2O
Element is simultaneously oxidized and reduced.
Types of Oxidation-Reduction Reactions
Chlorine Chemistry
0 +1 -1
4.4
Chemistry in Action: Metals from the SeaRedox or not?
CaCO3 (s) CaO (s) + CO2 (g)
Mg(OH)2 (s) + 2HCl (aq) MgCl2 (aq) + 2H2O (l)
CaO (s) + H2O (l) Ca2+ (aq) + 2OH (aq)-
Mg2+ (aq) + 2OH (aq) Mg(OH)2 (s)-
MgCl2 (aq) Mg (s) + Cl2 (g)
_______________
_______________
_______________
____________
_______________
Write half reactions for one of the redox reactions above:
ox:
red: