Skip to main content
Pearson+ LogoPearson+ Logo
Ch.14 - Chemical Kinetics
All textbooksBrown 14th EditionCh.14 - Chemical KineticsProblem 89
Chapter 14, Problem 89

Consider the reaction A + B ⇌ C + D. Is each of the following statements true or false? (d) The activation energy for the reverse reaction must be greater than that for the forward reaction.

Verified step by step guidance
1
Understand the concept of activation energy: Activation energy is the minimum energy required for a chemical reaction to occur. It is the energy barrier that must be overcome for reactants to transform into products.
Consider the energy profile of a reaction: In a chemical reaction, the energy profile diagram shows the energy changes during the reaction. The peak of the diagram represents the transition state, and the difference in energy between the reactants and the transition state is the activation energy.
Analyze the forward and reverse reactions: For the forward reaction A + B ⇌ C + D, the activation energy is the energy difference between the reactants (A + B) and the transition state. For the reverse reaction C + D ⇌ A + B, the activation energy is the energy difference between the products (C + D) and the transition state.
Compare the activation energies: The activation energy for the reverse reaction can be greater, equal, or less than that for the forward reaction depending on the energy levels of the reactants and products. The statement that the activation energy for the reverse reaction must be greater is not universally true; it depends on the specific energy profile of the reaction.
Evaluate the statement: To determine if the statement is true or false, consider the energy profile of the specific reaction. If the products are at a higher energy level than the reactants, the activation energy for the reverse reaction will be greater. However, if the products are at a lower energy level, the activation energy for the reverse reaction may be less than or equal to that of the forward reaction.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Activation Energy

Activation energy is the minimum energy required for a chemical reaction to occur. It represents the energy barrier that reactants must overcome to transform into products. In a reaction, the forward and reverse processes can have different activation energies, influencing the reaction rate and equilibrium position.
Recommended video:
Guided course
02:02
Activity Series Chart

Forward and Reverse Reactions

In a reversible reaction, the forward reaction converts reactants into products, while the reverse reaction converts products back into reactants. The activation energy for each direction can differ based on the energy profiles of the reactants and products. Understanding these differences is crucial for analyzing reaction dynamics and thermodynamics.
Recommended video:
Guided course
03:40
Reversible Changes in Matter

Reaction Coordinate Diagram

A reaction coordinate diagram visually represents the energy changes during a chemical reaction. It plots the energy of the system against the progress of the reaction, showing the activation energies for both the forward and reverse reactions. This diagram helps illustrate why the activation energy for the reverse reaction may or may not be greater than that for the forward reaction, depending on the relative energies of the reactants and products.
Recommended video:
Guided course
01:57
Energy Diagrams
Related Practice
Textbook Question

The activation energy of an uncatalyzed reaction is 95 kJ/mol. The addition of a catalyst lowers the activation energy to 55 kJ/mol. Assuming that the collision factor remains the same, by what factor will the catalyst increase the rate of the reaction at (a) 25 C

2
views
Textbook Question

The activation energy of an uncatalyzed reaction is 95 kJ/mol. The addition of a catalyst lowers the activation energy to 55 kJ/mol. Assuming that the collision factor remains the same, by what factor will the catalyst increase the rate of the reaction at (b) 125 °C?

Textbook Question

Consider the reaction A + B → C + D. Is each of the following statements true or false? (b) If the reaction is an elementary reaction, the rate law is second order.

Textbook Question

Consider the reaction A + B → C + D. Is each of the following statements true or false? (c) If the reaction is an elementary reaction, the rate law of the reverse reaction is first order.

Textbook Question

The reaction 2 NO(g) + O2(g) → 2 NO2 (g) is second order in NO and first order in O2. When [NO] = 0.040 M, and [O2] = 0.035 M, the observed rate of disappearance of NO is 9.3⨉10-5 M/s. (b) What is the value of the rate constant?