7.10

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7.10 Factors Influencing The rate of Reaction
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REVIEW

• What is the energy barrier that reactants must
  first scale before a reaction can occur.
• _______________ once we get them going they
  produce enough energy to become self-sustaining.
• _______________ we have to supply energy
  continuously.

ACTIVATION ENERGY
EXOTHERMIC
ENDOTHERMIC
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REVIEW

• How can we increase high energy collisions?
• INCREASE TEMPERATURE
• INCREASE CONCENTRATION
• INCREASE SURFACE AREA
• _______________ - the rate at which reactants
  disappear or, the rate at which products form
• What is the formula?

RATE OF REACTION
Rate of Reaction ? C ? t
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• Homogeneous Reactions reactions that occur
  uniformly throughout a solution / gaseous
  mixture.
• Heterogeneous Reactions reactions that occur at
  the interface between to phases.

(Surface Area)
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EXAMPLE (heterogeneous)

• A large lump of calcium carbonate (CaCO3) reacts
  with a solution of hydrochloric acid more slowly
  (left) than the same mass crushed into small
  pieces (right)

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Youve got 15 minutes to complete the following
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7.12 Temperature Effect Activation Energy
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Temperature

• As temperature increases, the average kinetic
  energy (and so the speed) of particles increases.
  This means that the rate of collision will
  increase, which will cause an increase in
  reaction rate.

However,
this effect alone does not explain
the very rapid increase in rate that we observe
when temperature increases. There is another more
important factor involved.
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ACTIVATION ENERGY

• In order for a reaction to proceed, it is
  necessary not only for the reactant molecules to
  collide, but also for the colliding molecules to
  possess a certain minimum amount of kinetic
  energy so that they can reach the top of the
  energy barrier.
• Once they reach the top they
• easily role down the other side
• of the hill and fall apart to
• products.

ACTIVATION ENERGY
If the colliding molecules dont have enough
energy, they bounce off and stay as reactants.
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ACTIVATION ENERGY

• Heating a substance increases the fraction of
  molecules that have sufficient energy to scale
  the activation energy and react.

500 K
300 K
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VISUAL DIAGRAM
300 K
500 K
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What you dont complete in class is homework.