Textbook Question
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) (a) What is the order of the reaction in A and B?
Ch.14 - Chemical Kinetics
McMurry8th EditionChemistryISBN: 9781292336145
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Table of contents
- Ch.1 - Chemical Tools: Experimentation & Measurement170
- Ch.2 - Atoms, Molecules & Ions160
- Ch.3 - Mass Relationships in Chemical Reactions169
- Ch.4 - Reactions in Aqueous Solution199
- Ch.5 - Periodicity & Electronic Structure of Atoms102
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory92
- Ch.7 - Covalent Bonding and Electron-Dot Structures61
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure59
- Ch.9 - Thermochemistry: Chemical Energy122
- Ch.10 - Gases: Their Properties & Behavior155
- Ch.11 - Liquids & Phase Changes54
- Ch.12 - Solids and Solid-State Materials73
- Ch.13 - Solutions & Their Properties120
- Ch.14 - Chemical Kinetics98
- Ch.15 - Chemical Equilibrium125
- Ch.16 - Aqueous Equilibria: Acids & Bases110
- Ch.17 - Applications of Aqueous Equilibria147
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium86
- Ch.19 - Electrochemistry154
- Ch.20 - Nuclear Chemistry96
- Ch.21 - Transition Elements and Coordination Chemistry156
- Ch.22 - The Main Group Elements187
- Ch.23 - Organic and Biological Chemistry51
Chapter 14, Problem 44
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?
Verified step by step guidance1
Step 1: Identify the reaction given: 2A -> A2.
Step 2: Observe the images provided, noting the number of A molecules at each time interval (0 min, 1 min, 2 min).
Step 3: Determine the change in concentration of A molecules over time by counting the number of A molecules at each time interval.
Step 4: Use the rate law expression for a reaction of the form 2A -> A2, which is rate = k[A]^2, where k is the rate constant.
Step 5: Conclude that the rate law for this reaction is rate = k[A]^2, indicating a second-order reaction with respect to A.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Rate Law
The rate law is an equation that relates the rate of a chemical reaction to the concentration of its reactants. It is typically expressed 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 predicting how changes in concentration affect the reaction rate.
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Rate Law Fundamentals
Reaction Order
Reaction order refers to the power to which the concentration of a reactant is raised in the rate law. It indicates how the rate of reaction is affected by the concentration of that reactant. For example, a first-order reaction means that the rate is directly proportional to the concentration of one reactant, while a second-order reaction indicates that the rate is proportional to the square of the concentration of that reactant.
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Molecularity
Molecularity is the number of reactant molecules involved in an elementary reaction step. It can be unimolecular (one molecule), bimolecular (two molecules), or termolecular (three molecules). In the context of the given reaction, where two A molecules combine to form A2, the reaction is bimolecular, which is important for determining the rate law and understanding the mechanism of the reaction.
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Related Practice
Textbook Question
What is the molecularity of each of the following elementary reactions?(a) (b) (c)
Textbook Question
Consider the first-order reaction AS B in which A molecules(red spheres) are converted to B molecules (blue spheres).(a) Given the pictures at t = 0 min and t = 1 min, drawpictures that show the number of A and B moleculespresent at t = 2 min and t = 3 min.
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
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 the reaction AS B in which A molecules (red spheres) are converted to B molecules (blue spheres).
(b) Draw a picture that shows the number of A and B molecules present at t = 3 min.