Chapter 6 Chemical Reactions

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Chapter 6Chemical Reactions

• Section 4
• Rates of Change
• p. 205

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Objectives

• Describe factors affecting reaction rates
• Understand the role of catalysts

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I. Factors Affecting Reaction Rates
A. Most are faster at higher temperatures
(usually doubles rate with 10C raise)
B. Faster with more exposed surface
area
C. Concentrated solutions work faster
D. Faster at higher pressures
E. Massive, bulky molecules react
slower
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F. Catalysts substances that speeds up a
reaction/changes rate without being consumed It
does not cause the reaction, only changes the rate
1. Inhibitor- slows down a reaction 2. Enzyme-
biological catalyst 3. Substrate- the compound
the catalyst works on
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II. Equilibrium Systems A. Some changes
(reactions) are reversible Increase
in pressure CO2 (gas above liquid) CO2
(gas dissolved in liquid)
Decrease pressure B. Equilibrium results
when rates balance (chemical equilibrium)
and respond to minimal change
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C. Le Chateliers Principle If a change is made
to a system in chemical equilibrium, the
equilibrium shifts to oppose the change until a
new equilibrium is reached
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Homework