Transcript Oxidation and Reduction

Oxidation and Reduction
Oxidation
The chemical process by which an element
or compound gains oxygen.
 Example: 2Mg(s) + O2  2MgO
Oxidation naturally happens to every
metal except platinum and gold.
 Oxidation can also be applied to any
element or compound which gives up
electrons in order to form a covalent or
ionic compounds.
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 Example: Cu(s)  Cu+2 + 2e-
Fe + O2  Fe2O3
Ag + O2  Ag2O
Oxygen cause food to spoil by
oxidation!
Reduction
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The chemical process by which an element or
compound loses oxygen.
This is how metal is refined. The oxygen is
removed in order to “reduce” metals to their
elemental form.
Example: 2 ZnO  2 Zn + O2
Reduction is also applied to any element or
compound which gains electrons in order to
form a covalent or ionic compounds.
Example: Fe+3 + 3e-  Fe
Redox
This is the name given to any reaction that involves a
gain of electrons by one compound and loss of electrons
by another.
 An easy way to remember which is to think of LEO the
Lion:
 LEO the lion says “GER”
 Lose Electrons— Oxidation
 Gain Electrons— Reduction
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You can recognize a redox reaction by assigning
oxidation numbers to each element in each compound
and look to see if they change from the reactant side to
the product side.
Example 1:
 Assign oxidation numbers first!
 +2 -1 0
+2 -1
0
 CuCl2 + Zn  ZnCl2 + Cu
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Zn
Species oxidized? ______
– Loses electrons - Zn0 to Zn2+
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Cu2+
Species reduced? ______
– Gains electrons - Cu2+ to Cu0
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Example 2:
+2 -2
0
0
+4 -2
 2CuO + C  Cu + CO2
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C
Species oxidized? ______
– Loses electrons - C0 to C+4
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Cu2+
Species reduced? ______
– Gains electrons – Cu+2 to Cu0
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Oxidizing Agent
a substance that can cause another substance to
be oxidized (lose electrons)
Strong oxidizing agents are those that want to
gain electrons the most, such as Fluorine,
oxygen and Chlorine. (they are electron
hungry!)
They are the substance that gets reduced!
Reducing Agent
a substance that can cause another substance to
be reduced (gain electrons)
Strong reducing agents are those that easily
give up electrons, such as Na, Li and K
They are the substance that gets oxidized!
Example
0
-1
-1
0
 Cl2 + 2Br1-(aq)  2Cl1-(aq) + Br2
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Species Oxidized =
Loses electrons = Br1-
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Species Reduced =
Gains electrons = Cl2
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Oxidizing agent =
Cl2
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Reducing agent =
Br1-