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AP Chemistry Practice Quiz: Thermodynamic and Kinetic Control

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 10 questions to check your progress.

Question 1 of 10

According to the provided text, why might a thermodynamically favored reaction not occur at a measurable rate?

All Questions (10)

According to the provided text, why might a thermodynamically favored reaction not occur at a measurable rate?

A) The reaction has reached equilibrium.

B) The process is thermodynamically unfavored.

C) The explanation is found in terms of kinetics.

D) The concentration of reactants is too low.

Correct Answer: C

The text explicitly states, 'Explain, in terms of kinetics, why a thermodynamically favored reaction might not occur at a measurable rate.' This indicates that the reason is related to the field of kinetics, not thermodynamics or equilibrium itself.

What is a common reason for a thermodynamically favored process to be under kinetic control?

A) A low activation energy.

B) A high activation energy.

C) The system being at equilibrium.

D) A positive change in enthalpy.

Correct Answer: B

The text directly states, 'High activation energy is a common reason for a process to be under kinetic control.'

A process is described as being 'under kinetic control.' What does this imply about the process?

A) It is thermodynamically favored but does not proceed at a measurable rate.

B) It is thermodynamically unfavored but proceeds at a very fast rate.

C) It has reached a state of dynamic equilibrium.

D) Its rate is determined solely by the temperature of the system.

Correct Answer: A

The text defines processes under 'kinetic control' as those that 'are thermodynamically favored but do not proceed at a measurable rate.'

Which statement is true for a kinetically controlled process that is not proceeding at a measurable rate?

A) The process is at equilibrium.

B) The process is not at equilibrium.

C) The process must be thermodynamically unfavored.

D) The process has a very low activation energy.

Correct Answer: B

The provided content specifies that 'A kinetically controlled process that is not proceeding is not at equilibrium.'

Many processes are thermodynamically favored yet occur at extremely slow rates. This observation highlights the importance of which concept?

A) Equilibrium constant

B) Enthalpy of formation

C) Kinetic control

D) Thermodynamic favorability

Correct Answer: C

The text explains that processes that are thermodynamically favored but occur slowly or not at all are under 'kinetic control.' This term encapsulates the concept being described.

A chemical reaction is known to be thermodynamically favored, but after several hours, no products are observed. What is the most likely conclusion based on the provided text?

A) The reaction is actually thermodynamically unfavored.

B) The system has reached equilibrium, and reactants are heavily favored.

C) The reaction is under kinetic control, likely due to a high activation energy.

D) The reaction must be reversible and has proceeded in the reverse direction.

Correct Answer: C

The text explains that thermodynamically favored processes that do not occur at a measurable rate are under 'kinetic control,' and a common reason for this is a 'high activation energy.'

The text states that some processes 'do not occur to any measurable extent.' This is often because they are...

A) at a state of high entropy.

B) under kinetic control.

C) thermodynamically controlled.

D) in a state of perfect equilibrium.

Correct Answer: B

The text directly links the phenomenon of thermodynamically favored processes not occurring to a measurable extent with the concept of being under 'kinetic control.'

A student incorrectly claims that a thermodynamically favored reaction that shows no signs of proceeding must be at equilibrium. Which piece of information from the text directly refutes this claim?

A) High activation energy is a common reason for a process to be under kinetic control.

B) Many processes that are thermodynamically favored do not occur to any measurable extent.

C) A kinetically controlled process that is not proceeding is not at equilibrium.

D) The reason a reaction might not occur is explained in terms of kinetics.

Correct Answer: C

The text provides a direct contradiction to the student's claim: 'A kinetically controlled process that is not proceeding is not at equilibrium.' The lack of an observable reaction does not automatically mean equilibrium has been reached.

The concepts of thermodynamics and kinetics are used to explain reaction behavior. According to the text, which concept explains the *rate* at which a favored reaction occurs?

A) Thermodynamics, because it determines favorability.

B) Kinetics, because it deals with the reaction pathway and activation energy.

C) Equilibrium, because it describes the final state of the reaction.

D) Both thermodynamics and kinetics equally determine the rate.

Correct Answer: B

The text distinguishes between thermodynamic favorability and the rate of reaction. It explains that the reason a favored reaction might not occur at a measurable rate is due to 'kinetics' and factors like 'high activation energy,' which are central to the study of kinetics.

If a reaction is thermodynamically favored, what must be true about its kinetic properties for it to proceed at a very slow or immeasurable rate?

A) The reaction must have a low activation energy.

B) The reaction must be at equilibrium.

C) The reaction must be under kinetic control.

D) The reaction must be reversible.

Correct Answer: C

The text defines the exact scenario—a thermodynamically favored reaction that proceeds very slowly—as being 'under kinetic control.' This implies a kinetic barrier, such as high activation energy, is preventing the reaction from occurring quickly.