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Edexcel IAL Chemistry 9.2 Activation energy and successful collisions

Read Eₐ from the reactant level to the profile peak, then reject collisions below that minimum even when particles meet; temperature changes the qualifying fraction.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
AS

Exam points

  • Identify activation energy as the minimum collision energy shown on a reaction profile.
  • Explain unsuccessful collisions by insufficient energy rather than concentration or equilibrium.
  • Link high activation barriers to repulsion or bond breaking when the context provides it.

9.2—Reactions take place only when collisions have sufficient energy, known as the activation energy question 1

[Maximum number: 1]

A Maxwell-Boltzmann distribution curve for the particles present in a reaction mixture is shown. Number of particles with energy, E

Figure for Question 9.2—Reactions take place only when collisions have sufficient energy, known as the activation energy question 1 — Edexcel A-Level Chemistry AS

Which statement is correct?

A

position X represents the mean energy of the particles

B

activation energy, EaE_{\mathrm{a}}, is the mean energy of the particles that react

C

the area under the curve to the right of the activation energy, EaE_{\mathrm{a}}, represents the number of particles with enough energy to react

D

adding a catalyst moves the activation energy, EaE_{\mathrm{a}}, to the right

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