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 45
What is the molecularity of each of the following elementary reactions?(a) 
(b) ![]()
(c) ![]()
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Identify the number of reactant molecules involved in each elementary reaction.
For the first reaction (leftmost), count the number of individual reactant molecules.
For the second reaction (middle), count the number of individual reactant molecules.
For the third reaction (rightmost), count the number of individual reactant molecules.
Determine the molecularity based on the number of reactant molecules: unimolecular (1 molecule), bimolecular (2 molecules), or termolecular (3 molecules).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Molecularity
Molecularity refers to the number of reactant molecules involved in an elementary reaction. It is classified as unimolecular (one molecule), bimolecular (two molecules), or termolecular (three molecules). Understanding molecularity is crucial for predicting reaction mechanisms and rates, as it directly influences how reactants collide and interact during a reaction.
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02:38
Molecular Polarity
Elementary Reactions
Elementary reactions are single-step processes that occur in a chemical reaction, where reactants convert directly to products without any intermediates. Each elementary reaction has a specific molecularity, which can be determined by analyzing the number of reactant species involved. These reactions are fundamental to understanding the kinetics of more complex reactions.
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03:06Reaction Mechanism Overview
Reaction Mechanism
A reaction mechanism is a detailed description of the step-by-step process by which reactants are converted into products. It includes the sequence of elementary reactions and the molecularity of each step. Understanding the mechanism helps chemists predict the rate of reaction and the conditions under which the reaction occurs, providing insights into the overall chemical behavior.
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Related Practice
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
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
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.