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Section 16.1
The Nature of OxidationReduction Reactions
Section 16.2
Applications of OxidationReduction Reactions
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The Nature of Oxidation-Reduction Reactions
• Analyze the characteristics of an oxidationreduction reaction.
• Distinguish between oxidation reactions and
reduction reactions by definition.
• Identify the substances that are oxidized and
those that are reduced in a redox reaction.
• Distinguish oxidizing and reducing agents in
redox reactions.
The Nature of Oxidation-Reduction Reactions
buffer: a solution that resists changes in pH
when moderate amounts of acids or bases
are added
The Nature of Oxidation-Reduction Reactions
oxidation-reduction
reaction
oxidizing agent
reducing agent
oxidation
reduction
Oxidation and reduction are
complementary—as an atom is
oxidized, another atom is reduced.
What is oxidation-reduction?
• A chemical reaction in which electrons are
transferred from one atom or ion to another
is called an oxidation-reduction reaction,
or a redox reaction.
– Oxygen is not always involved in redox
reactions.
What is oxidation-reduction? (cont.)
• Oxidation is defined as the loss of
electrons by the atoms or ions of a
substance.
• Reduction is defined as the gain of electrons
by the atoms or ions of a substance.
• Oxidation and reduction reactions always
occur together.
What is oxidation-reduction? (cont.)
• The oxidation number of an atom in an
ionic compound is the number of electrons
lost or gained by the atom when it forms
an ion.
• When an atom or ion gains electrons, the
numerical value of its oxidation number
decreases.
What is oxidation-reduction? (cont.)
• When an atom or ion loses electrons, its
oxidation number increases.
• Oxidation numbers are tools that scientists
use to keep track of the movement of
electrons in a redox reaction.
What is oxidation-reduction? (cont.)
What is oxidation-reduction? (cont.)
What is oxidation-reduction? (cont.)
Identifying a Redox Reaction
• An oxidizing agent is the substance that
gains electrons in a redox reaction.
– The oxidizing agent is the substance that is
reduced in a redox reaction.
Identifying a Redox Reaction (cont.)
• A reducing agent is the substance that
loses electrons in a redox reaction.
– The reducing agent is the substance that is
oxidized.
Identifying a Redox Reaction (cont.)
Section Assessment
What type of reaction involves the transfer
of electrons from one atom to another?
A. synthesis
B. decomposition
C. double replacement
D. redox
Section Assessment
Which of the following is not a redox
reaction?
A. formation of rust
B. combustion of fuels
C. formation of zinc oxide
D. none of the above
Applications of Oxidation-Reduction Reactions
• Analyze common redox processes to identify
the oxidizing and reducing agents.
• Identify some redox reactions that take place
in living cells.
Applications of Oxidation-Reduction Reactions
oxidation: reaction in which an element loses
electrons
Oxidation and reduction reactions are
among the most common reactions in
both nature and industry.
Everyday Redox Reactions
• Redox reactions can reduce metals found
in ores to their pure states.
– Developing camera film
– Blast furnace
Everyday Redox Reactions (cont.)
• Bleach oxidizes the molecules that cause
stains, resulting in colorless molecules.
– Disinfectants
– Removing stains from clothing
Everyday Redox Reactions (cont.)
• Metals, such as copper and aluminum,
react with oxygen to form protective
coatings on the surface of the metal.
Everyday Redox Reactions (cont.)
• Chemiluminescent reactions in emergency
light sticks, lightening, and the luminol
reaction convert the energy of chemical
bonds into light energy.
– Bioluminescence—fireflies, fish,
mushrooms, and caterpillars
• Antioxidants, such as vitamin C and E, can
protect fruit from browning.
Section Assessment
Which of the following is considered an
antioxidant?
A. vitamins C and E
B. vitamins E and K
C. vitamins D and C
D. vitamins A and B
Section Assessment
Which of the following is not a
biochemical redox reaction?
A. bioluminescence
B. photosynthesis
C. respiration
D. none of the above
Chemistry Online
Study Guide
Chapter Assessment
Standardized Test Practice
Image Bank
Concepts in Motion
Key Concepts
• Oxidation occurs when an atom or ion loses one or
more electrons. Reduction takes place when an
atom or ion gains electrons.
• Oxidation and reduction reactions always occur
together in a net process called a redox reaction.
• An oxidizing agent gains electrons and is reduced
during a redox reaction. A reducing agent loses
electrons and is oxidized during a redox reaction.
Key Concepts
• Redox reactions can reduce metals found in ores to
their pure states.
• Bleach oxidizes the molecules that cause stains to
form colorless molecules.
• Metals such as copper and aluminum react with
oxygen to form protective coatings on the surface of
the metal.
• Chemiluminescent reactions in emergency light
sticks, lightning, and the luminol reaction convert the
energy of chemical bonds into light energy.
What is the oxidizing agent when iron
rusts?
A. iron
B. oxygen
C. water
D. carbon
An example of an everyday redox
reaction is:
A. silver tarnishing
B. chemiluminescence
C. browning fruit
D. all of the above
When an atom loses electrons, its
oxidation number ___.
A. increases
B. decreases
C. stays the same
For an oxidation-reduction reaction to
occur, one of the elements must be
oxygen.
A. true
B. false
The redox reaction that converts
chemical bonds into light energy is
called a(n) ___ reaction.
A. exothermic
B. oxidizing
C. photosynthesis
D. chemiluminescent
Which of the following is not a way to
prevent rust from forming?
A. painting the metal
B. galvanization
C. demagnetizing the metal
D. none of the above
Which of the following is a natural redox
reaction?
A. developing camera film
B. removing stains from clothing with bleach
C. making steel in a blast furnace
D. gases emitted from volcanic vents
Metals such as copper and aluminum
react with carbon dioxide to form
protective coatings on the surface of the
metal.
A. true
B. false
What do scientists use to keep track of
the movement of electrons in a redox
reaction?
A. oxidation numbers
B. oxidizing agents
C. reducing agents
D. redox numbers
The substance that loses electrons in a
redox reaction is the:
A. oxidizing agent
B. reducing agent
C. standard solution
D. oxide
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Figure 16.4
Oxidation-Reduction Reaction
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