AP Chemistry Flashcards: Multistep Reaction Energy Profile
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
What do the 'peaks' or local energy maxima on a multistep energy profile represent?
Each peak represents the transition state for one of the elementary steps in the reaction mechanism.
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What do the 'peaks' or local energy maxima on a multistep energy profile represent?
Each peak represents the transition state for one of the elementary steps in the reaction mechanism.
On a multistep reaction energy profile, how do you identify the rate-determining step?
The rate-determining step corresponds to the elementary step with the highest activation energy barrier on the profile.
How can you determine if a multistep reaction is exothermic or endothermic by looking at its energy profile?
The reaction is exothermic if the final products are at a lower energy level than the initial reactants (negative overall energy change), and endothermic if the products are at a higher energy level.
If a reaction mechanism consists of three elementary steps, how many transition states will its energy profile show?
The energy profile will show three transition states, as each elementary step has its own unique transition state represented by a peak on the profile.
What is a reaction energy profile for a multistep reaction?
It is a graph that illustrates the potential energy changes occurring during a reaction, showing the activation energy for each elementary step and the overall energy change from reactants to products.
What do the 'valleys' or local energy minima between the peaks on a multistep energy profile represent?
These valleys represent the formation of reaction intermediates, which are species that are produced in one elementary step and consumed in a subsequent step.
How is the overall energy change (ΔE) of a multistep reaction represented on its energy profile?
The overall energy change is represented by the difference in potential energy between the final products and the initial reactants.
For a two-step reaction, how is the activation energy of the second step represented on the energy profile?
It is represented by the energy difference between the reaction intermediate (the valley) and the peak of the second energy barrier (the second transition state).
What information is essential for constructing an energy profile for a multistep reaction?
Knowledge of the energetics, specifically the activation energy and energy change, for each individual elementary step in the reaction mechanism is required.
What does the term 'Activation Energy (Ea)' represent for an elementary step on an energy profile?
Activation energy is the minimum energy required to initiate a chemical reaction, represented as the energy difference between the reactants of that step and the peak of the energy barrier (the transition state).