A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 × 10−4 mol L−1and the rate constant k = 1.08 × 10−6 s−1, what concentration of R remains after 25 days?

A) 1.0 × 10 −3 mol L −1 B) 1.0 × 10 −4 mol L −1 C) 9.6 × 10 −5 mol L −1 D) 4.3 × 10 −5 mol L −1 E) 9.7 × 10 −6 mol L −1 A) 1.0 × 10 −3 mol L −1 B) 1.0 × 10 −4 mol L −1 C) 9.6 × 10 −5 mol L −1 D) 4.3 × 10 −5 mol L −1 E) 9.7 × 10 −6 mol L −1

Ammonium cyanate (NH4CNO) reacts to form urea (NH2CONH2). At 65°C the rate constant, k, is 3.60 L mol−1s−1. What is the rate law for this reaction?

A) Rate = 3.60 L mol −1s −1[NH 4CNO] B) Rate = 3.60 L mol −1s −1[NH 4CNO] 2 C) Rate = 0.28 mol L −1 s −1[NH 4CNO] D) Rate = 0.28 mol L −1 s −1[NH 4CNO] 2 E) Rate = 3.60 L mol −1s −1[NH 2CONH 2] −1 A) Rate = 3.60 L mol −1s −1[NH 4CNO] B) Rate = 3.60 L mol −1s −1[NH 4CNO] 2 C) Rate = 0.28 mol L −1 s −1[NH 4CNO] D) Rate = 0.28 mol L −1 s −1[NH 4CNO] 2 E) Rate = 3.60 L mol −1s −1[NH 2CONH 2] −1

The rate law for the reaction 3A → C is Rate = 4.36 × 10−2 L mol−1 hr−1 [A]2 What is the half-life for the reaction if the initial concentration of A is 0.250 M?

A) 0.0109 hr B) 0.0629 hr C) 15.9 hr D) 23.9 hr E) 91.7 hr A) 0.0109 hr B) 0.0629 hr C) 15.9 hr D) 23.9 hr E) 91.7 hr

The radioactive isotope tritium decays with a first-order rate constant k of 0.056 year−1. What fraction of the tritium initially in a sample is still present 30 years later?

A) 0.19 B) 0.60 C) 0.15 D) 2.8 × 10 −38 E) None of these choices are correct. A) 0.19 B) 0.60 C) 0.15 D) 2.8 × 10 −38 E) None of these choices are correct.

Consider the reaction 2A + 2B + C → 2D + E If the rate law for this reaction is Rate = k[A][B]2, what will be the effect on the rate if the concentrations of A, B and C are all doubled at the same time?

A) The rate will increase by a factor of 2. B) The rate will increase by a factor of 4. C) The rate will increase by a factor of 6. D) The rate will increase by a factor of 8. E) More information is needed before this question can be answered. A) The rate will increase by a factor of 2. B) The rate will increase by a factor of 4. C) The rate will increase by a factor of 6. D) The rate will increase by a factor of 8. E) More information is needed before this question can be answered.

Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. H+ + H2O2 ⇄ H2O+−OH (rapid equilibrium)H2O+−OH + Br− → HOBr + H2O (slow)HOBr + H+ + Br− → Br2 + H2O (fast) What is the overall reaction equation for this process?

A) 2H 2O +−OH + 2Br − → H 2O 2 + Br 2 + 2H 2O B) 2H + + 2Br − + H 2O 2 → Br 2 + 2H 2O C) 2H + + H 2O 2 + Br − + HOBr → H 2O +−OH + Br 2 + H 2O D) H 2O +−OH + Br − + H + → Br 2 + H 2O E) None of these choices are correct. A) 2H 2O +−OH + 2Br − → H 2O 2 + Br 2 + 2H 2O B) 2H + + 2Br − + H 2O 2 → Br 2 + 2H 2O C) 2H + + H 2O 2 + Br − + HOBr → H 2O +−OH + Br 2 + H 2O D) H 2O +−OH + Br − + H + → Br 2 + H 2O E) None of these choices are correct.

A reaction has the following rate law: Rate = k[A][B]2 In experiment 1, the concentrations of A and B are both 0.10 mol L−1; in experiment 2, the concentrations are both 0.30 mol L−1. If the temperature stays constant, what is the value of the ratio, Rate(2)/Rate(1)?

A) 3.0 B) 6.0 C) 9.0 D) 18 E) 27 A) 3.0 B) 6.0 C) 9.0 D) 18 E) 27

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 1020 molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

A) 1.00 × 10 4 molecules B) 2.00 × 10 19 molecules C) 3.20 × 10 16 molecules D) 5.00 × 10 20 molecules E) None of these choices are correct. A) 1.00 × 10 4 molecules B) 2.00 × 10 19 molecules C) 3.20 × 10 16 molecules D) 5.00 × 10 20 molecules E) None of these choices are correct.

Tetrafluoroethylene, C2F4, can be converted to octafluorocyclobutane which can be used as a refrigerant or an aerosol propellant. A plot of 1/[C2F4] vs. time gives a straight line with a slope of 0.0448 L mol−1s−1. What is the rate law for this reaction?

A) Rate = 0.0448 (L mol −1s −1)[C 2F 4] B) Rate = 22.3 (mol L −1s)[C 2F 4] C) Rate = 0.0448 (L mol −1s −1)[C 2F 4] 2 D) Rate = 22.3 (mol L −1s)[C 2F 4] 2 E) Rate = 0.0448 s −1 [C 2F 4] A) Rate = 0.0448 (L mol −1s −1)[C 2F 4] B) Rate = 22.3 (mol L −1s)[C 2F 4] C) Rate = 0.0448 (L mol −1s −1)[C 2F 4] 2 D) Rate = 22.3 (mol L −1s)[C 2F 4] 2 E) Rate = 0.0448 s −1 [C 2F 4]

Exam 16: Kinetics: Rates and Mechanisms of Chemical Reactions

The reaction of ethylene (C₂H₄) with butadiene (C₄H₆) to form cyclohexene (C₆H₁₀) has an activation energy (E_a) of 115 kJ/mol. The reverse reaction (decomposition of cyclohexene to ethylene and butadiene) has an activation energy of 287 kJ/mol. What is the heat of reaction, Δ H_rxn, for the forward reaction?

(Multiple Choice)

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Question 41

A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 × 10⁻⁴ mol L⁻¹and the rate constant k = 1.08 × 10⁻⁶ s⁻¹, what concentration of R remains after 25 days?

(Multiple Choice)

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Question 42

Ammonium cyanate (NH₄CNO) reacts to form urea (NH₂CONH₂). At 65°C the rate constant, k, is 3.60 L mol⁻¹s⁻¹. What is the rate law for this reaction?

(Multiple Choice)

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Question 43

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L⁻¹s⁻¹, at what rate is [B] changing?

(Multiple Choice)

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Question 44

The rate law for the reaction 3A → C is Rate = 4.36 × 10⁻² L mol⁻¹hr⁻¹ [A]² What is the half-life for the reaction if the initial concentration of A is 0.250 M?

(Multiple Choice)

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Question 45

Which of the following affects the activation energy of a reaction?

(Multiple Choice)

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Question 46

The radioactive isotope tritium decays with a first-order rate constant k of 0.056 year⁻¹. What fraction of the tritium initially in a sample is still present 30 years later?

(Multiple Choice)

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Question 47

A transition state is a species (or state) corresponding to an energy maximum on a reaction energy diagram.

(True/False)

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Question 48

Consider the reaction 2A + 2B + C → 2D + E If the rate law for this reaction is Rate = k[A][B]², what will be the effect on the rate if the concentrations of A, B and C are all doubled at the same time?

(Multiple Choice)

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Question 49

An increase in temperature increases the reaction rate because

(Multiple Choice)

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Question 50

Chlorine atoms act as heterogeneous catalysts in the destruction of ozone in the stratosphere.

(True/False)

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Question 51

Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. H⁺+ H₂O₂ ⇄ H₂O⁺−OH (rapid equilibrium)H₂O⁺−OH + Br⁻ → HOBr + H₂O (slow)HOBr + H⁺ + Br⁻ → Br₂+ H₂O (fast) What is the overall reaction equation for this process?

(Multiple Choice)

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Question 52

All second-order reactions are bimolecular reactions.

(True/False)

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Question 53

If the activation energy of a reaction decreases by 10.0 kJ/mol, from 100.0 to 90.0 kJ/mol, what effect will this have on the rate of reaction at 298K?

(Multiple Choice)

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Question 54

When the reaction A → B + C is studied, a plot 1/[A]_t vs. time gives a straight line with a positive slope. What is the order of the reaction?

(Multiple Choice)

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Question 55

The units of the rate constant depend on the order of the reaction.

(True/False)

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Question 56

A reaction has the following rate law: Rate = k[A][B]² In experiment 1, the concentrations of A and B are both 0.10 mol L⁻¹; in experiment 2, the concentrations are both 0.30 mol L⁻¹. If the temperature stays constant, what is the value of the ratio, Rate(2)/Rate(1)?

(Multiple Choice)

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Question 57

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 10²⁰ molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

(Multiple Choice)

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Question 58

Tetrafluoroethylene, C₂F₄, can be converted to octafluorocyclobutane which can be used as a refrigerant or an aerosol propellant. A plot of 1/[C₂F₄] vs. time gives a straight line with a slope of 0.0448 L mol⁻¹s⁻¹. What is the rate law for this reaction?

(Multiple Choice)

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Question 59

The decomposition of dinitrogen pentaoxide to nitrogen dioxide and oxygen follows first-order kinetics and has an activation energy of 102 kJ/mol. By what factor will the fraction of collisions with energy greater than or equal to the activation energy increase if the reaction temperature goes from 30°C to 60°C?

(Multiple Choice)

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Question 60

Showing 41 - 60 of 78

Exam 16: Kinetics: Rates and Mechanisms of Chemical Reactions

A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 × 10−4 mol L−1and the rate constant k = 1.08 × 10−6 s−1, what concentration of R remains after 25 days?

Ammonium cyanate (NH4CNO) reacts to form urea (NH2CONH2). At 65°C the rate constant, k, is 3.60 L mol−1s−1. What is the rate law for this reaction?

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L−1s−1, at what rate is [B] changing?

The rate law for the reaction 3A → C is Rate = 4.36 × 10−2 L mol−1 hr−1 [A]2 What is the half-life for the reaction if the initial concentration of A is 0.250 M?

Which of the following affects the activation energy of a reaction?

The radioactive isotope tritium decays with a first-order rate constant k of 0.056 year−1. What fraction of the tritium initially in a sample is still present 30 years later?

A transition state is a species (or state) corresponding to an energy maximum on a reaction energy diagram.

Consider the reaction 2A + 2B + C → 2D + E If the rate law for this reaction is Rate = k[A][B]2, what will be the effect on the rate if the concentrations of A, B and C are all doubled at the same time?

An increase in temperature increases the reaction rate because

Chlorine atoms act as heterogeneous catalysts in the destruction of ozone in the stratosphere.

Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. H+ + H2O2 ⇄ H2O+−OH (rapid equilibrium)H2O+−OH + Br− → HOBr + H2O (slow)HOBr + H+ + Br− → Br2 + H2O (fast) What is the overall reaction equation for this process?

All second-order reactions are bimolecular reactions.

If the activation energy of a reaction decreases by 10.0 kJ/mol, from 100.0 to 90.0 kJ/mol, what effect will this have on the rate of reaction at 298K?

When the reaction A → B + C is studied, a plot 1/[A]t vs. time gives a straight line with a positive slope. What is the order of the reaction?

The units of the rate constant depend on the order of the reaction.

A reaction has the following rate law: Rate = k[A][B]2 In experiment 1, the concentrations of A and B are both 0.10 mol L−1; in experiment 2, the concentrations are both 0.30 mol L−1. If the temperature stays constant, what is the value of the ratio, Rate(2)/Rate(1)?

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 1020 molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

Tetrafluoroethylene, C2F4, can be converted to octafluorocyclobutane which can be used as a refrigerant or an aerosol propellant. A plot of 1/[C2F4] vs. time gives a straight line with a slope of 0.0448 L mol−1s−1. What is the rate law for this reaction?

Keys to the Study of Chemistry: Definitions, Units, and Problem Solving

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main-Group Elements

Organic Compounds and the Atomic Properties of Carbon

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, Free Energy, and Reaction Direction

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 × 10⁻⁴ mol L⁻¹and the rate constant k = 1.08 × 10⁻⁶ s⁻¹, what concentration of R remains after 25 days?

Ammonium cyanate (NH₄CNO) reacts to form urea (NH₂CONH₂). At 65°C the rate constant, k, is 3.60 L mol⁻¹s⁻¹. What is the rate law for this reaction?

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L⁻¹s⁻¹, at what rate is [B] changing?

The rate law for the reaction 3A → C is Rate = 4.36 × 10⁻² L mol⁻¹hr⁻¹ [A]² What is the half-life for the reaction if the initial concentration of A is 0.250 M?

The radioactive isotope tritium decays with a first-order rate constant k of 0.056 year⁻¹. What fraction of the tritium initially in a sample is still present 30 years later?

Consider the reaction 2A + 2B + C → 2D + E If the rate law for this reaction is Rate = k[A][B]², what will be the effect on the rate if the concentrations of A, B and C are all doubled at the same time?

When the reaction A → B + C is studied, a plot 1/[A]_t vs. time gives a straight line with a positive slope. What is the order of the reaction?

A reaction has the following rate law: Rate = k[A][B]² In experiment 1, the concentrations of A and B are both 0.10 mol L⁻¹; in experiment 2, the concentrations are both 0.30 mol L⁻¹. If the temperature stays constant, what is the value of the ratio, Rate(2)/Rate(1)?

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 10²⁰ molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

Tetrafluoroethylene, C₂F₄, can be converted to octafluorocyclobutane which can be used as a refrigerant or an aerosol propellant. A plot of 1/[C₂F₄] vs. time gives a straight line with a slope of 0.0448 L mol⁻¹s⁻¹. What is the rate law for this reaction?