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AQA
Physical
3.1.5 Kinetics
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Created by
Paul Evangelou
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Cards (14)
Collision theory:
Reactions can only occur when
collisions
take place between particles that have sufficient energy
Energy needed to
break bonds
in reactants
Activation energy
: the minimum energy which particles need to
collide
to start a
reaction
What does the Maxwell-Boltzmann distribution show? the
spread of energies
that molecules of a gas have at a particular
temperature
Describe how the Maxwell-Boltzman distribution curve will change when you increase temperature:
Total area should
remain
constant
Molecules have a
wider range
of energies than at lower temperatures
Both
most probable
and
mean energy
have higher energies
Rate of reaction
: The change in
concentration
of a substance in
unit time
Explain how increasing concentration affect the rate of reaction:
More particles
per unit volume
More
frequent collisions
Rate of reaction
increases
What is the effect of increasing temperature on the rate of reaction?
Particles have increased
kinetic energy
Many more particles have
E
>= Ea
Many more
successful collisions
Significant increase in
rate of
reaction
How does increasing surface area affect the rate of reaction?
More
particles
exposed
More
frequent collisions
Rate of reaction
increases
Catalyst
: Substances that increase
reaction
rates without getting
used up
How do catalysts work? They provide an alternative route/mechanism with a
lower
activation energy
Why does lowering activation energy increase the rate of reaction?
more particles have energy
above
activation energy
higher frequency
of effective collisions
Minimum energy in collision theory is called
activation energy
What must particles do in order to react? Collide with
sufficient energy
(activation energy) and the correct
orientation
Do most collisions result in a reaction?
no