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Activation energy and temperature change in reactions

Energy changes • Exothermic and endothermic reactions

Key concepts

What you'll likely be quizzed about

  • Activation energy is the minimum energy required for reactant particles to form an activated complex and proceed to products.
  • It corresponds to the energy difference between reactants and the transition state on an energy profile diagram.
  • A reaction occurs only if some colliding particles have kinetic energy equal to or greater than the activation energy.

Flashcards

Test your knowledge with interactive flashcards

Observable sign of an exothermic reaction

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An exothermic reaction raises the temperature of the surroundings because of the net release of energy.

Key notes

Important points to keep in mind

Activation energy is the minimum energy barrier for a reaction.

Activation energy is represented in energy profile diagrams as the gap to the transition state.

Raising temperature increases the fraction of particles with energy above activation energy, enhancing reaction rate.

Catalysts lower activation energy without changing overall energy change.

Exothermic reactions raise surrounding temperature due to net energy release.

Endothermic reactions lower surrounding temperature due to net energy absorption.

Collision frequency and particle energy determine how many collisions surpass activation energy.

Temperature change observations provide evidence of net energy flow.

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