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A Level Chemistry A
Topic Exploration Pack
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Boltzmann Distribution Curves
Learner Questions
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Sketch the following graph on to a
plain piece of A4 paper
T1
Ea
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Tasks
1. Label the x and y axes
2. If you calculated the area under the
graph, what would this number be a
measure of?
3. What does the shaded area under the
graph represent?
4. What does the line labelled Ea
represent?
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Tasks
5. The graph you have drawn represents
the distribution of energies of molecules
in a sample of gases. On your diagram,
sketch a second distribution curve, for
the same gas, but at a lower
temperature, label this T2.
6. What has happened to the proportion of
molecules above line Ea? How would this
affect the rate of a reaction?
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Tasks
7. Are the areas under the two curves
equal? Explain your answer.
8. Now sketch another curve, on the same
axes, for the same sample of gases at a
higher temperature, label this T3.
9. What has happened to the area beyond
the line Ea?
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Tasks
10. Other than by changing the temperature,
how else could you increase the area
beyond the line Ea?
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Answers
T2
T1
T2
Ea
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Answers
1. See graph on previous slide.
2. Total number of particles present.
3. Number of particles with an energy
higher than the activation energy.
4. Activation energy.
5. See previous slide.
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Answers
6. Fewer molecules with an energy above
the activation energy, so fewer collisions
will lead to a reaction.
7. Yes, the area under the two curves are
equal because the sample of gases is
the same.
8. See Slide 9.
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Answers
9. The area has increased, so there are
now more molecules with an energy
above the activation energy.
10. A catalyst could be added, which would
lower the activation energy, hence
increasing the number of molecules with
an energy above the activation energy.
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