Textbook Question
The reaction 2 NO2 → 2 NO + O2 has the rate constant k = 0.63 M-1s-1. (a) Based on the units for k, is the reaction first or second order in NO2?
Ch.14 - Chemical Kinetics
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement140
- Ch.2 - Atoms, Molecules, and Ions192
- Ch.3 - Chemical Reactions and Reaction Stoichiometry172
- Ch.4 - Reactions in Aqueous Solution156
- Ch.5 - Thermochemistry151
- Ch.6 - Electronic Structure of Atoms137
- Ch.7 - Periodic Properties of the Elements127
- Ch.8 - Basic Concepts of Chemical Bonding143
- Ch.9 - Molecular Geometry and Bonding Theories167
- Ch.10 - Gases147
- Ch.11 - Liquids and Intermolecular Forces97
- Ch.12 - Solids and Modern Materials129
- Ch.13 - Properties of Solutions126
- Ch.14 - Chemical Kinetics175
- Ch.15 - Chemical Equilibrium107
- Ch.16 - Acid-Base Equilibria127
- Ch.17 - Additional Aspects of Aqueous Equilibria133
- Ch.18 - Chemistry of the Environment88
- Ch.19 - Chemical Thermodynamics140
- Ch.20 - Electrochemistry137
- Ch.21 - Nuclear Chemistry99
- Ch.22 - Chemistry of the Nonmetals66
- Ch.23 - Transition Metals and Coordination Chemistry69
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry11
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
Chapter 14, Problem 91d
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. (d) What would happen to the rate if the concentration of NO were increased by a factor of 1.8?
Verified step by step guidance1
Identify the rate law for the reaction. Since the reaction is second order in NO and first order in O2, the rate law can be expressed as: , where k is the rate constant.
Use the given rate of disappearance of NO to find the rate constant k. Substitute the given concentrations and rate into the rate law: . Solve for k.
Determine the new concentration of NO when it is increased by a factor of 1.8. Multiply the initial concentration of NO by 1.8: .
Substitute the new concentration of NO into the rate law to find the new rate. Use the previously calculated rate constant k and the unchanged concentration of O2: .
Compare the new rate to the original rate to understand the effect of increasing the concentration of NO. Since the rate is proportional to the square of the concentration of NO, increasing NO by a factor of 1.8 will increase the rate by a factor of .
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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 expresses the relationship between the rate of a chemical reaction and the concentration of its reactants. For the given reaction, the rate law can be written as Rate = k[NO]^2[O2]^1, indicating that the rate is second order with respect to NO and first order with respect to O2. Understanding the rate law is crucial for predicting how changes in concentration affect the reaction rate.
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Rate Law Fundamentals
Order of Reaction
The order of a reaction refers to the power to which the concentration of a reactant is raised in the rate law. In this case, the reaction is second order in NO, meaning that if the concentration of NO is doubled, the rate of reaction increases by a factor of four. This concept is essential for determining how changes in concentration influence the overall reaction rate.
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Effect of Concentration on Rate
The effect of concentration on the rate of a reaction is determined by the reaction's order with respect to each reactant. For the given reaction, increasing the concentration of NO by a factor of 1.8 will increase the rate of disappearance of NO by a factor of (1.8)^2, since the reaction is second order in NO. This principle allows us to calculate the new rate based on changes in concentration.
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Related Practice
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?
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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. (c) What are the units of the rate constant?
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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.
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Textbook Question
Consider the following reaction between mercury(II) chloride and oxalate ion:
2 HgCl2(aq) + C2O42-(aq) → 2 Cl-(aq) + 2 CO2(g) + Hg2Cl2(s)
The initial rate of this reaction was determined for several concentrations of HgCl2 and C2O42-, and the following rate data were obtained for the rate of disappearance of C2O42-:
Experiment [HgCl2] (M) [C2O42-] (M) Rate (M/s)
1 0.164 0.15 3.2 × 10-5
2 0.164 0.45 2.9 × 10-4
3 0.082 0.45 1.4 × 10-4
4 0.246 0.15 4.8 × 10-5
(b) What is the value of the rate constant with proper units?
(c) What is the reaction rate when the initial concentration of HgCl2 is 0.100 M and that of C2O42- is 0.25 M if the temperature is the same as that used to obtain the data shown?
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