Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780137542970

Ch.14 - Chemical Kinetics

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Brown 15th Edition

Ch.14 - Chemical Kinetics

Problem 27a

A reaction A + B → C obeys the following rate law: Rate = k[B]². (a) If [A] is doubled, how will the rate change? Will the rate constant change?

Problem 27b

A reaction A + B → C obeys the following rate law: Rate = k[B]². (b) What are the reaction orders for A and B? What is the overall reaction order?

Problem 27c

A reaction A + B → C obeys the following rate law: Rate = k[B]². (c) What are the units of the rate constant?

Problem 28a

Consider a hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. (a) Write the rate law for the reaction.

Problem 28b,c,d,f

Consider a hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. (b) How does the rate change when [A] is doubled and the other reactant concentrations are held constant? (c) How does the rate change when [B] is tripled and the other reactant concentrations are held constant? (d) How does the rate change when [C] is tripled and the other reactant concentrations are held constant? (f) By what factor does the rate change when the concentrations of all three reactants are cut in half?

Problem 28e

Consider a hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. (e) By what factor does the rate change when the concentrations of all three reactants are tripled?

Problem 29a

The decomposition reaction of N₂O₅ in carbon tetrachloride is 2 N₂O₅ → 4 NO₂ + O₂. The rate law is first order in N₂O₅. At 64°C the rate constant is 4.82 × 10^-3 s^-1. (a) Write the rate law for the reaction.

Problem 29c,d

The decomposition reaction of N₂O₅ in carbon tetrachloride is 2 N₂O₅ → 4 NO₂ + O₂. The rate law is first order in N₂O₅. At 64°C the rate constant is 4.82 × 10^-3 s^-1. (c) What happens to the rate when the concentration of N₂O₅ is doubled to 0.0480 M? (d) What happens to the rate when the concentration of N₂O₅ is halved to 0.0120 M?

Problem 30d

Consider the following reaction: 2 NO1g2 + 2 H21g2¡N21g2 + 2 H2O1g2 (d) What is the reaction rate at 1000 K if [NO] is decreased to 0.010 M and 3H24 is increased to 0.030 M?

Problem 32a

The reaction between ethyl bromide (C₂H₅Br) and hydroxide ion in ethyl alcohol at 330 K, C₂H₅Br(alc) + OH^-(alc) → C₂H₅OH(l) + Br^-(alc), is first order each in ethyl bromide and hydroxide ion. When [C₂H₅Br] is 0.0477 M and [OH^-] is 0.100 M, the rate of disappearance of ethyl bromide is 1.7×10^-7 M/s. (a) What is the value of the rate constant?

Problem 32b

Problem 32c

Problem 33a

The iodide ion reacts with hypochlorite ion (the active ingredient in chlorine bleaches) in the following way: OCl^- + I^- → OI^- + Cl^- . This rapid reaction gives the following rate data:

[OCl₄^-] (M) [I^-] (M) Initial Rate (M,s)

1.5 * 10-3 1.5 * 10-3

1.36 * 10-4 3.0 * 10-3 1.5 * 10-3 2.72 * 10-4

1.5 * 10-3 3.0 * 10-3 2.72 * 10-4

(a) Write the rate law for this reaction.

Problem 33b

The iodide ion reacts with hypochlorite ion (the active ingredient in chlorine bleaches) in the following way: OCl - + I - ¡OI - + Cl - . This rapid reaction gives the following rate data:

[OCl₄^-] (M) [I^-] (M) Initial Rate (M,s)

1.5 * 10-3 1.5 * 10-3

1.36 * 10-4 3.0 * 10-3 1.5 * 10-3 2.72 * 10-4

1.5 * 10-3 3.0 * 10-3 2.72 * 10-4

(b) Calculate the rate constant with proper units.

Problem 33c

The iodide ion reacts with hypochlorite ion (the active ingredient in chlorine bleaches) in the following way: OCl^- + I^- → OI^- + Cl^- . This rapid reaction gives the following rate data:

[OCl₄^-] (M) [I^-] (M) Initial Rate (M,s)

1.5 * 10-3 1.5 * 10-3

1.36 * 10-4 3.0 * 10-3 1.5 * 10-3 2.72 * 10-4

1.5 * 10-3 3.0 * 10-3 2.72 * 10-4 (c) Calculate the rate when [OCl^-] = 2.0 * 10-3 M and [I^-] = 5.0 * 10 - 4 M.

Problem 34

The reaction 2 ClO2(aq) + 2 OH-(aq) → ClO3-(aq) + ClO2-(aq) + H2O(l) was studied with the following results: Experiment [ClO2] (M) [OH-] (M) Initial Rate (M/s) 1 0.060 0.030 0.0248 2 0.020 0.030 0.00276 3 0.020 0.090 0.00828. (c) Calculate the rate when [ClO2] = 0.100 M and [OH-] = 0.050 M.

Problem 35b

The following data were measured for the reaction BF₃(g) + NH₃(g) → F₃BNH₃(g):

Experiment [BF₃] (M) [NH₃] (M) Initial Rate (M/s)

1 0.250 0.250 0.2130

2 0.250 0.125 0.1065

3 0.200 0.100 0.0682

4 0.350 0.100 0.1193

5 0.175 0.100 0.0596

(b) What is the overall order of the reaction?

Problem 35c

The following data were measured for the reaction BF₃(g) + NH₃(g) → F₃BNH₃(g):

Experiment [BF₃] (M) [NH₃] (M) Initial Rate (M/s)

1 0.250 0.250 0.2130

2 0.250 0.125 0.1065

3 0.200 0.100 0.0682

4 0.350 0.100 0.1193

5 0.175 0.100 0.0596

Problem 36

The following data were collected for the rate of disappearance of NO in the reaction 2 NO(g) + O2(g) → 2 NO2(g): Experiment [NO] (M) [O2] (M) Initial Rate (M/s) 1 0.0126 0.0125 1.41 * 10^-2 2 0.0252 0.0125 5.64 * 10^-2 3 0.0252 0.0250 1.13 * 10^-1 (d) What is the rate of disappearance of NO when [NO] = 0.0750 M and [O2] = 0.0100 M? (e) What is the rate of disappearance of O2 at the concentrations given in part (d)?

Problem 38a

Consider the reaction of peroxydisulfate ion (S₂O₈^2-) with iodide ion (I^-) in aqueous solution:

S₂O₈^2-(aq) + 3 I^-(aq) → 2 SO₄^2-(aq) + I₃^-(aq)

At a particular temperature, the initial rate of disappearance of S₂O₈^2- varies with reactant concentrations in the following manner:

Experiment [S₂O₈^2-] (M) [I^-] (M) Initial Rate (M/s)

1 0.018 0.036 2.6 × 10^-6

2 0.027 0.036 3.9 × 10^-6

3 0.036 0.054 7.8 × 10^-6

4 0.050 0.072 1.4 × 10^-5

(a) Determine the rate law for the reaction and state the units of the rate constant.

Problem 39a

(a) For the generic reaction A → B what quantity, when graphed versus time, will yield a straight line for a first-order reaction?

Problem 41a

(a) The gas-phase decomposition of SO₂Cl₂, SO₂Cl₂(g) → SO₂(g) + Cl₂(g), is first order in SO₂Cl₂. At 600 K the half-life for this process is 2.3 × 10⁵ s. What is the rate constant at this temperature?

Problem 41b

(b) At 320°C the rate constant is 2.2 × 10^-5 s^-1. What is the half-life at this temperature?

Problem 42

Molecular iodine, I2(g), dissociates into iodine atoms at 625 K with a first-order rate constant of 0.271 s-1. (b) If you start with 0.050 M I2 at this temperature, how much will remain after 5.12 s assuming that the iodine atoms do not recombine to form I2?

Problem 43a

As described in Exercise 14.41, the decomposition of sulfuryl chloride (SO₂Cl₂) is a first-order process. The rate constant for the decomposition at 660 K is 4.5 × 10^-2 s^-1. (a) If we begin with an initial SO₂Cl₂ pressure of 450 torr, what is the partial pressure of this substance after 60 s?

Problem 43b

As described in Exercise 14.41, the decomposition of sulfuryl chloride (SO₂Cl₂) is a first-order process. The rate constant for the decomposition at 660 K is 4.5 × 10^-2 s^-1. (b) At what time will the partial pressure of SO₂Cl₂ decline to one-tenth its initial value?

Problem 44a

The first-order rate constant for the decomposition of N₂O₅, 2 N₂O₅(g) → 4 NO₂(g) + O₂(g), at 70°C is 6.82×10^-3 s^-1. Suppose we start with 0.0250 mol of N₂O₅(g) in a volume of 2.0 L. (a) How many moles of N₂O₅ will remain after 5.0 min?

Problem 44c

Problem 45

The reaction SO2Cl2(g) → SO2(g) + Cl2(g) is first order in SO2Cl2. Using the following kinetic data, determine the magnitude and units of the first-order rate constant: Time (s) Pressure SO2Cl2 (atm) 0 1.000 2500 0.947 5000 0.895 7500 0.848 10,000 0.803

Problem 47a

Consider the data presented in Exercise 14.19. (a) By using appropriate graphs, determine whether the reaction is first order or second order.