AP Chemistry · Unit 5: Kinetics
5.9 Pre-Equilibrium Approximation
In short
You must understand that if the first elementary reaction in a mechanism is not the rate-limiting step, approximations (such as the pre-equilibrium approximation) must be made to determine the overall rate law expression.
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How is Pre-Equilibrium Approximation tested on the exam?
This topic is assessed under the 'Mathematical Routines' skill (5.B), requiring you to identify an appropriate theory, definition, or mathematical relationship to solve a problem. On the AP Exam, you are expected to navigate between a proposed mechanism and a constructed rate law, applying the pre-equilibrium approximation to derive the rate law when the first step is fast and reversible.
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Pre-Equilibrium Approximation: common questions
What do you need to know about Pre-Equilibrium Approximation for AP Chemistry?
You must understand that if the first elementary reaction in a mechanism is not the rate-limiting step, approximations (such as the pre-equilibrium approximation) must be made to determine the overall rate law expression.
How is Pre-Equilibrium Approximation tested on the AP Chemistry exam?
This topic is assessed under the 'Mathematical Routines' skill (5.B), requiring you to identify an appropriate theory, definition, or mathematical relationship to solve a problem. On the AP Exam, you are expected to navigate between a proposed mechanism and a constructed rate law, applying the pre-equilibrium approximation to derive the rate law when the first step is fast and reversible.
Where does Pre-Equilibrium Approximation fit in AP Chemistry?
Pre-Equilibrium Approximation is topic 5.9 in Unit 5: Kinetics of AP Chemistry.
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