becomes oxidized

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• Please turn in the lab from Tuesday if you
haven’t done so already.
• Homework: Chapter 7 – Due Wed, Nov 5th at
10:00 pm
Chapter 7
Oxidation and Reduction
Energy transfers
Overview: Life Is Work
• Living cells require energy from outside sources.
© 2014 Pearson Education, Inc.
Figure 7.2
Light
energy
ECOSYSTEM
CO2  H2O
Photosynthesis
in chloroplasts
Cellular respiration
in mitochondria
ATP
Heat
energy
Organic
 O2
molecules
ATP powers
most cellular work
Concept 7.1: Catabolic pathways yield energy by
oxidizing organic fuels
• The breakdown of organic molecules is exergonic.
• Fermentation is a partial degradation of sugars
that occurs without O2.
• Aerobic respiration consumes organic molecules
and O2 and yields ATP.
• Anaerobic respiration is similar to aerobic
respiration but consumes compounds other than
O2.
© 2014 Pearson Education, Inc.
• Although carbohydrates, fats, and proteins are all
consumed as fuel, it is helpful to trace cellular
respiration with the sugar glucose.
C6H12O6  6 O2  6 CO2  6 H2O  Energy (ATP  heat)
© 2014 Pearson Education, Inc.
Redox Reactions: Oxidation and Reduction
• The transfer of electrons during chemical
reactions releases energy stored in organic
molecules.
• This released energy is ultimately used to
synthesize ATP.
© 2014 Pearson Education, Inc.
The Principle of Redox
• Chemical reactions that transfer electrons
between reactants are called oxidation-reduction
reactions, or redox reactions.
• In oxidation, a substance loses electrons, or is
oxidized.
• In reduction, a substance gains electrons, or is
reduced (the amount of positive charge is
reduced).
© 2014 Pearson Education, Inc.
The Principle of Redox
• Chemical reactions that transfer electrons
between reactants are called oxidation-reduction
reactions, or redox reactions.
© 2014 Pearson Education, Inc.
Figure 7.UN01
becomes oxidized
(loses electron)
becomes reduced
(gains electron)
Figure 7.UN02
becomes oxidized
becomes reduced
Figure 7.3
Reactants
Products
becomes oxidized
becomes reduced
Methane
(reducing
agent)
Oxygen
(oxidizing
agent)
Carbon dioxide
Water
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