Domanda del libro di testo
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
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970
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TOC.tableOfContents
- Ch.1 - Introduction: Matter, Energy, and Measurement146
- Ch.2 - Atoms, Molecules, and Ions200
- Ch.3 - Chemical Reactions and Reaction Stoichiometry176
- Ch.4 - Reactions in Aqueous Solution155
- Ch.5 - Thermochemistry126
- Ch.6 - Electronic Structure of Atoms131
- Ch.7 - Periodic Properties of the Elements126
- Ch.8 - Basic Concepts of Chemical Bonding123
- Ch.9 - Molecular Geometry and Bonding Theories143
- Ch.10 - Gases147
- Ch.11 - Liquids and Intermolecular Forces91
- Ch.12 - Solids and Modern Materials122
- Ch.13 - Properties of Solutions126
- Ch.14 - Chemical Kinetics174
- Ch.15 - Chemical Equilibrium101
- Ch.16 - Acid-Base Equilibria139
- Ch.17 - Additional Aspects of Aqueous Equilibria146
- Ch.18 - Chemistry of the Environment72
- Ch.19 - Chemical Thermodynamics129
- Ch.20 - Electrochemistry142
- Ch.21 - Nuclear Chemistry101
- Ch.22 - Chemistry of the Nonmetals68
- Ch.23 - Transition Metals and Coordination Chemistry66
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry10
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Non è quello che usi tu?Cambia libro di testo
Capitolo 14, Problema 97
A first-order reaction A → B has the rate constant k = 3.2 * 10^-3 s^-1. If the initial concentration of A is 2.5 * 10^-2 M, what is the rate of the reaction at t = 660 s?
Guida verificata passo dopo passo1
Step 1: Understand that for a first-order reaction, the rate of the reaction is given by the formula: rate = k[A], where k is the rate constant and [A] is the concentration of A at time t.
Step 2: Use the integrated rate law for a first-order reaction to find the concentration of A at time t. The integrated rate law is: ln([A]_t/[A]_0) = -kt, where [A]_t is the concentration at time t, [A]_0 is the initial concentration, and t is the time.
Step 3: Substitute the given values into the integrated rate law: ln([A]_t/2.5 \(\times\) 10^{-2}) = -(3.2 \(\times\) 10^{-3}) \(\times\) 660.
Step 4: Solve the equation from Step 3 to find [A]_t, the concentration of A at time t = 660 s.
Step 5: Substitute the value of [A]_t obtained in Step 4 into the rate equation from Step 1 to calculate the rate of the reaction at t = 660 s.
Concetti chiave
Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.
First-Order Reactions
First-order reactions are chemical reactions where the rate is directly proportional to the concentration of one reactant. This means that as the concentration of the reactant decreases, the rate of the reaction also decreases. The rate law for a first-order reaction can be expressed as rate = k[A], where k is the rate constant and [A] is the concentration of the reactant.
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02:29
First-Order Reactions
Rate Constant (k)
The rate constant (k) is a proportionality factor in the rate law that is specific to a given reaction at a specific temperature. It indicates how quickly a reaction proceeds; a larger k value signifies a faster reaction. For first-order reactions, the units of k are typically s^-1, reflecting the dependence of the reaction rate on the concentration of the reactant.
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Percorso guidato
01:14Equilibrium Constant K
Integrated Rate Law for First-Order Reactions
The integrated rate law for a first-order reaction relates the concentration of the reactant at any time (t) to its initial concentration and the rate constant. It is expressed as ln([A]0/[A]) = kt, where [A]0 is the initial concentration, [A] is the concentration at time t, and k is the rate constant. This equation allows for the calculation of concentration changes over time, which is essential for determining the rate of the reaction at a specific time.
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Percorso guidato
02:29First-Order Reactions
Pratica correlata
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Americium-241 is used in smoke detectors. It has a first-order rate constant for radioactive decay of k = 1.6 * 10-3 yr-1. By contrast, iodine-125, which is used to test for thyroid functioning, has a rate constant for radioactive decay of k = 0.011 day-1. (a) What are the half-lives of these two isotopes? (b) Which one decays at a faster rate?
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Domanda del libro di testo
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Domanda del libro di testo
Consider two reactions. Reaction (1) has a constant halflife, whereas reaction (2) has a half-life that gets longer as the reaction proceeds. What can you conclude about the rate laws of these reactions from these observations?
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Domanda del libro di testo
The reaction 2 NO2 → 2 NO + O2 has the rate constant k = 0.63 M-1s-1.
(b) If the initial concentration of NO2 is 0.100 M, how would you determine how long it would take for the concentration to decrease to 0.025 M?
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