1. Transfer of Electrons
An oxidation–reduction reaction
 transfers electrons from one reactant to another
Oxidation Is a Loss of electrons
Zn(s) Zn2+(aq) + 2e−
Reduction Is a Gain of electrons
Cu2+(aq) + 2e−
Cu(s)
1
(OIL)
(RIG)
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2. Oxidation and Reduction
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3. Oxidized or Reduced?
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4. Zn and Cu 2+
oxidation
Zn(s)
Silvery metal
Zn2+(aq) + 2ereduction
Cu2+(aq) + 2e-
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General, Organic, and Biological Chemistry
Cu(s)
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5. Electron Transfer from Zn to
Cu 2+
Oxidation: electron loss
Reduction: electron gain
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6. Learning Check
Identify each of the following as:
1) oxidation or 2) reduction
__A. Sn(s)
__B. Fe3+(aq) + 1e−
Fe2+(aq)
__C. Cl2(g) + 2e−
6
Sn4+(aq) + 4e−
2Cl−(aq)
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7. Solution
Identify each of the following as:
1) oxidation or 2) reduction
1 A. Sn(s)
2 B. Fe3+(aq) + 1e−
Fe2+(aq)
2 C. Cl2(g) + 2e−
7
Sn4+(aq) + 4e−
2Cl−(aq)
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8. Writing Oxidation and
Reduction Reactions
Write the separate oxidation and reduction reactions for the
following equation.
2Cs(s) + F2(g)
2CsF(s)
Each cesium atom loses an electron to form a cesium ion.
2Cs(s)
2Cs+(s) + 2e−
oxidation
Each fluorine atom gains an electron to form a fluoride ion.
F2(s) + 2e–
8
General, Organic, and Biological Chemistry
2F−(s)
reduction
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9. Learning Check
In light-sensitive sunglasses, UV light initiates an
oxidation–reduction reaction.
uv light
Ag+ + Cl−
Ag + Cl
A. Which reactant is oxidized?
B. Which reactant is reduced?
9
General, Organic, and Biological Chemistry
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10. Solution
In light-sensitive sunglasses, UV light initiates an oxidationreduction reaction.
uv light
Ag+ + Cl−
Ag + Cl
A. Which reactant is oxidized?
Cl − Cl−
Cl + 1e−
B. Which reactant is reduced?
Ag+
Ag+ + 1e−
10
General, Organic, and Biological Chemistry
Ag
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11. Learning Check
Identify the substances that are oxidized and reduced in
each of the following reactions:
A. Mg(s) + 2H+(aq)
Mg2+(aq) + H2(g)
B. 2Al(s) + 3Br2(g)
11
General, Organic, and Biological Chemistry
2AlBr3(s)
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12. Solution
Identify the substances that are oxidized and reduced in
each of the following reactions:
A. Mg is oxidized
Mg(s)
Mg2+(aq) + 2e−
H+ is reduced
2H+ + 2e−
H2
B. Al is oxidized
Br is reduced
12
General, Organic, and Biological Chemistry
2Al
2Br + 2e−
2Al3+ + 6e−
2Br−
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13. Oxidation–Reduction in
Biological Systems
In biological systems, oxidation may involve
 the loss of H
 the gain of O
In biological systems, reduction may involve
 the gain of H
 the loss of O
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14. Oxidation–Reduction in
Biological Systems (continued)
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15. Summar y of Oxidation and
Reduction
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