Skip to main content
Pearson+ LogoPearson+ Logo
Ch.14 - Chemical Kinetics
All textbooksMcMurry 8th EditionCh.14 - Chemical KineticsProblem 46
Chapter 14, Problem 46

The relative rates of the reaction A + B S AB in vessels(1)–(3) are 4:4:1. Red spheres represent A molecules, andblue spheres represent B molecules.(1)-(3) Three vessels showing red spheres for A and blue for B, with reaction rates 4:4:1.
(a) What is the order of the reaction in A and B?

Verified step by step guidance
1
Identify the number of A and B molecules in each vessel. Vessel 1: 2 A and 3 B, Vessel 2: 4 A and 3 B, Vessel 3: 3 A and 2 B.
Note the given relative rates of the reaction in vessels 1, 2, and 3, which are 4:4:1.
Set up the rate law expression for the reaction: rate = k[A]^m[B]^n.
Compare the rates and concentrations between vessels to determine the reaction order. For example, compare vessels 1 and 2 to find the order with respect to A, and compare vessels 1 and 3 to find the order with respect to B.
Solve the equations derived from the comparisons to find the values of m and n, which represent the order of the reaction with respect to A and B, respectively.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2m
Was this helpful?

Key Concepts

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

Reaction Order

The reaction order refers to the power to which the concentration of a reactant is raised in the rate law of a chemical reaction. It indicates how the rate of reaction is affected by the concentration of reactants. For example, a first-order reaction in A means that doubling the concentration of A will double the reaction rate, while a second-order reaction means that doubling A will quadruple the rate.
Recommended video:
Guided course
00:36
Average Bond Order

Rate Law

The rate law expresses the relationship between the rate of a chemical reaction and the concentration of its reactants. It is typically written in the form Rate = k[A]^m[B]^n, where k is the rate constant, and m and n are the orders of the reaction with respect to reactants A and B, respectively. Understanding the rate law is crucial for determining how changes in concentration affect the reaction rate.
Recommended video:
Guided course
01:52
Rate Law Fundamentals

Stoichiometry of the Reaction

Stoichiometry involves the quantitative relationships between the reactants and products in a chemical reaction. In this case, the stoichiometry of the reaction A + B → AB can help determine the relative amounts of A and B that react. The given rates of reaction in different vessels can be analyzed to infer the stoichiometric coefficients, which are essential for deducing the order of the reaction in A and B.
Recommended video:
Guided course
01:16
Stoichiometry Concept
Related Practice
Textbook Question

The following pictures represent the progress of the reaction AS B in which A molecules (red spheres) are converted to B molecules (blue spheres).

(c) Suppose that each sphere represents 6.0⨉1021 molecules and that the volume of the container is 1.0 L. What is the rate constant for the reaction in the usual units?

Textbook Question
The following pictures represent the progress of a reaction in which two A molecules combine to give a more complex molecule A2, 2 AS A2.

(b) What is the rate law?
Textbook Question
What is the molecularity of each of the following elementary reactions?(a)

(b)

(c)

Textbook Question

Consider a reaction that occurs by the following mechanism:

A + BC → AC + B

AC + D → A + CD

The potential energy profile for this reaction is as follows:

(b) Write structural formulas for all species present at reaction stages 1–5. Identify each species as a reactant, product, catalyst, intermediate, or transition state.

Textbook Question

Consider a reaction that occurs by the following mechanism:

A + BC → AC + B

AC + D → A + CD

The potential energy profile for this reaction is as follows:

(c) Which of the two steps in the mechanism is the rate-determining step? Write the rate law for the overall reaction.

Textbook Question

Consider a reaction that occurs by the following mechanism:

A + BC → AC + B

AC + D → A + CD

The potential energy profile for this reaction is as follows:

(d) Is the reaction endothermic or exothermic? Add labels to the diagram that show the values of the energy of reaction ΔE and the activation energy Ea for the overall reaction.