Deck 15: Chemical Kinetics

Question 1

The following questions refer to the hypothetical reaction A + B $\rightarrow$ products. The kinetics data given can be analyzed to answer the questions.

-The rate expression for a particular reaction is Rate = k[A][B]³. If the initial concentration of B is increased from 0.2 M to 0.6 M, the initial rate will increase by which of the following factors?

A) 6
B) 3
C) 27
D) 4
E) 12

Answer 1

27

Question 2

A general reaction written as 2A + 2B $\rightarrow$ C + 2D is studied and yields the following data.

-For the first of the reactions in the table of data, determine - $\Delta$ [B]/ $\Delta$ t.

A) 8.00* 10^-5
B) 1.60*10^-4
C) 4.00 *10^-5
D) 2.00 *10^-5
E) none of these

Answer 2

8.00* 10^-5

Question 3

A general reaction written as 2A + 2B $\rightarrow$ C + 2D is studied and yields the following data.

-What is the overall order of the reaction?

A) 0
B) 2
C) 3
D) 4
E) 1

Answer 3

1

Question 4

The following questions refer to the hypothetical reaction A + B $\rightarrow$ products. The kinetics data given can be analyzed to answer the questions.

-The rate law for the reaction is Rate = k[A]^x[B]^y. What are the values of x and y?

A) x = 1 y = 0
B) x = 1 y = 1
C) x = 0 y = 1
D) x = 1 y = 2
E) x = 2 y = 1

Question 5

The rate constant k is dependent on

A) the concentration of the product.
B) the order of the reaction.
C) the temperature.
D) the concentration of the reactant.
E) none of these

Question 6

The following questions refer to the hypothetical reaction A + B $\rightarrow$ products. The kinetics data given can be analyzed to answer the questions.

-What form will the pseudo-rate law have?

A) Rate = kk'[A]^x
B) Rate = k'[A]^x[B]^y
C) Rate = kk'[B]^y
D) Rate = k'[B]^y
E) Rate = k'[A]^x

Question 7

The oxidation of Cr³⁺ to CrO₄^2- can be accomplished using Ce⁴⁺ in a buffered solution. The following data were obtained:
Determine the order in the rate law of the species Ce⁴⁺.

A) 1
B) -2
C) 3
D) -1
E) 2

Question 8

A general reaction written as 2A + 2B $\rightarrow$ C + 2D is studied and yields the following data.

-What are the proper units for the rate constant for the reaction?

A) L mol^-1 s^-1
B) s^-1
C) L³ mol^-3 s^-1
D) mol L^-1 s^-1
E) L² mol^-2 s^-1

Question 9

For the reaction 2N₂O₅(g) $\rightarrow$ 4NO₂(g) + O₂(g), the following data were collected. The initial rate of production of NO₂ for this reaction is approximately

A) 6.4 *10^-4 mol/L • min
B) 3.2*10^-4 mol/L • min
C) 1.24* 10^-2 mol/L • min
D) 1.6 * 10^-4 mol/L • min
E) none of these

Question 10

A general reaction written as 2A + 2B $\rightarrow$ C + 2D is studied and yields the following data.

-What is the order of the reaction with respect to A?

A) 1
B) 0
C) 4
D) 3
E) 2

Question 11

A general reaction written as 2A + 2B $\rightarrow$ C + 2D is studied and yields the following data.

-What is the order of the reaction with respect to B?

A) 3
B) 2
C) 4
D) 1
E) 0

Question 12

The oxidation of Cr³⁺ to CrO₄^2- can be accomplished using Ce⁴⁺ in a buffered solution. The following data were obtained:
Determine the order in the rate law of the species Cr³⁺.

A) -2
B) 3
C) 1
D) 2
E) -1

Question 13

The balanced equation for the reaction of bromate ion with bromide in acidic solution is BrO+ 5Br^- + 6H⁺ $\rightarrow$ 3Br₂ + 3H₂O
At a particular instant in time, the value of - $\Delta$ [Br^-]/ $\Delta$ t is 2.0 * 10^-3 mol/L • s. What is the value of $\Delta$ [Br₂]/ $\Delta$ t in the same units?

A) 1.2 * 10^-3
B) 2.0 * 10^-3
C) 6.0 *10^-3
D) 3.3*10^-5
E) 3.3 * 10^-3

Question 14

A general reaction written as 2A + 2B $\rightarrow$ C + 2D is studied and yields the following data.

-What is the numerical value of the rate constant?

A) 4.00 * 10^-1
B) 4.00* 10^-2
C) 4.00 * 10^-3
D) 4.00 * 10^-4
E) none of these

Question 15

The oxidation of Cr³⁺ to CrO₄^2- can be accomplished using Ce⁴⁺ in a buffered solution. The following data were obtained:
Determine the order in the rate law of the species Ce³⁺.

A) -1
B) 2
C) 3
D) -2
E) 1

Question 16

The reaction
H₂SeO₃(aq) + 6I^-(aq) + 4H⁺(aq) $\rightarrow$ 2I₃^-(aq) + 3H₂O(l) + Se(s)
was studied at 0°C by the method of initial rates:

-What is the rate law?

A) Rate = k[H₂SeO₃][H⁺][I^-]²
B) Rate = k[H₂SeO₃][H⁺]²[I^-]³
C) Rate = k[H₂SeO₃][H⁺][I^-]
D) Rate = k[H₂SeO₃][H⁺]²[I^-]
E) Rate = k[H₂SeO₃]²[H⁺][I^-]

Question 17

The average rate of disappearance of ozone in the reaction 2O₃(g) $\rightarrow$ 3O₂(g) is found to be 9.6 *10^-3 atm over a certain interval of time. What is the rate of appearance of O₂ during this interval?

A) 6.4* 10^-3 atm/time
B) 2.9 *10^-2 atm/time
C) 1.9 * 10^-2 atm/time
D) 1.4 *10^-2 atm/time
E) 9.6* 10^-3 atm/time

Question 18

A first-order reaction is 54% complete at the end of 12 min. What is the value of the rate constant?

A) 0.065 min^-1
B) 0.33 min^-1
C) 6.5 * 10^-2 min^-1
D) 2.8* 10^-2 min^-1
E) 5.1*10^-2 min^-1

Question 19

For the reaction
2A + B $\rightarrow$ products
the following mechanism is proposed:
A + B M
A + M $\rightarrow$ products
A catalyst never appears in a rate law.

Question 20

The following data were obtained for the reaction of NO with O₂. Concentrations are in molecules/cm³ and rates are in molecules/cm³ • s. Which of the following is the correct rate law?

A) Rate = k[NO]²
B) Rate = k[NO]²[O₂]²
C) Rate = k[NO][O₂]²
D) Rate = k[NO][O₂]
E) Rate = k[NO]²[O₂]

Question 21

For which of the following is the half-life directly dependent on the concentration of the reactant?

A) zero-order reaction
B) second-order reaction
C) first-order reaction
D) two of these
E) all of these

Question 22

Initial rate data have been determined at a certain temperature for the gaseous reaction 2NO + 2H₂ $\rightarrow$ N₂ + 2H₂O What is the numerical value of the rate constant?

A) 1.1
B) 6.9
C) 2.2
D) 0.11
E) 0.35

Question 23

The following initial rate data were found for the reaction
2MnO₄^- + 5H₂C₂O₄ + 6H⁺ $\rightarrow$ 2Mn²⁺ + 10CO₂ + 8H₂O

-Which of the following is the correct rate law?

A) Rate = k[MnO₄^-][H₂C₂O₄][H⁺]
B) Rate = k[MnO₄^-]²[H₂C₂O₄][H⁺]
C) Rate = k[MnO₄^-]²[H₂C₂O₄]
D) Rate = k[MnO₄^-][H₂C₂O₄]²
E) Rate = k[MnO₄^-]²[H₂C₂O₄]⁵[H⁺]⁶

Question 24

The following initial rate data were found for the reaction
2MnO₄^- + 5H₂C₂O₄ + 6H⁺ $\rightarrow$ 2Mn²⁺ + 10CO₂ + 8H₂O

-For which order reaction is the half-life of the reaction independent of the initial concentration of the reactant(s)?

A) zero order
B) first order
C) second order
D) all of these
E) none of these

Question 25

Use the following initial rate data for the reaction in aqueous solution to determine the rate law.

A) Rate = k[CH₃COCH₃][H⁺]
B) Rate = k[CH₃COCH₃][Br₂][H⁺]
C) Rate = k[Br₂][H⁺]
D) Rate = k[CH₃COCH₃][Br₂][H⁺]²
E) Rate = k[CH₃COCH₃][Br₂]

Question 26

The following initial rate data were found for the reaction
2MnO₄^- + 5H₂C₂O₄ + 6H⁺ $\rightarrow$ 2Mn²⁺ + 10CO₂ + 8H₂O

-What is the value of the rate constant?

A) 2 * 10⁵ M • s^-1
B) 2 * 10⁵ M^-2 • s^-1
C) 200 M^-2 • s^-1
D) 2 *10^-4 M • s^-1
E) 200 M^-1 • s^-1

Question 27

The reaction of (CH₃)₃CBr with hydroxide ion proceeds with the formation of (CH₃)₃COH. (CH₃)₃CBr (aq) + OH^- (aq) $\rightarrow$ (CH₃)₃COH (aq) + Br^- (aq)
The following data were obtained at 55°C. What will the initial rate (in mol/L • s) be in Experiment 4?

A) 18 *10^-3
B) 6.0 * 10^-3
C) 9.0 * 10^-3
D) 3.0* 10^-3
E) none of these

Question 28

For the reaction in which A and B react to form C, the following initial rate data were obtained. What is the rate law for the reaction?

A) Rate = k[A]²[B]²
B) Rate = k[A]²[B]
C) Rate = k[A][B]²
D) Rate = k[A][B]
E) Rate = k[A]³

Question 29

The following questions refer to the hypothetical reaction A + B $\rightarrow$ products. The kinetics data given can be analyzed to answer the questions. Determine the magnitude of the pseudo-rate constant (k') if the magnitude of X in the rate data is 0.00905.

A) 0.31
B) 1.81 *10^-3
C) 4.3 *10^-3
D) 0.86
E) 1.2 * 10^-2

Question 30

The OH radical disproportionates according to the elementary chemical reaction OH + OH $\rightarrow$ H₂O + O. This reaction is second order in OH. The rate constant for the reaction is 2.2 *10^-12 cm³/molecule • s at room temperature. If the initial OH concentration is 1.8 *10¹³ molecules/cm³, what is the first half-life for the reaction?

A) 3.2*10¹¹ s
B) 0.025 s
C) 4.1 * 10²⁴ s
D) 3.7 s
E) 5.1 s

Question 31

For the reaction A + B $\rightarrow$ products, the following data were obtained. What is the experimental rate law?

A) Rate = k[A]²[B]
B) Rate = k[B]
C) Rate = k[A][B]
D) Rate = k[A]
E) Rate = k[A][B] ²

Question 32

Tabulated below are initial rate data for the reaction 2Fe(CN)₆^3- + 2I^- $\rightarrow$ 2Fe(CN)₆^4- + I₂ What is the value of k?

A) 10³ M^-3 s^-1
B) 50 M^-2 s^-1
C) 10 M^-2 s^-1
D) 10⁷ M^-5 s^-1
E) none of these

Question 33

What is the rate law for the following reaction, given the data below? 2NO + H₂ $\rightarrow$ N₂O + H₂O

A) Rate = k[N₂O][H₂O]
B) Rate = k[NO][H₂]
C) Rate = k[NO]²[H₂]
D) Rate = k[NO]
E) Rate = k[NO]²

Question 34

The following initial rate data were found for the reaction
2MnO₄^- + 5H₂C₂O₄ + 6H⁺ $\rightarrow$ 2Mn²⁺ + 10CO₂ + 8H₂O

-The reaction A $\rightarrow$ B + C is known to be zero order in A with a rate constant of 5.0 *10^-2 mol/L • s at 25° C. An experiment was run at 25°C where [A]₀ = 1.0 *10^-3 M. What is the integrated rate law?

A) [A] = kt
B) [A]₀ - [A] = kt
C)
D) [A] - [A]₀ = kt
E)

Question 35

The decomposition of N₂O₅(g) to NO₂(g) and O₂(g) obeys first-order kinetics. Assume the form of the rate law is
Rate where k = 3.4 *10^-5 s^-1 at 25°C.

-What is the initial rate of reaction at 25°C where [N₂O₅]₀ = 5.0 *10^-2 M?

A) 3.4 * 10^-5 mol/L • s
B) 5.0 * 10^-2 mol/L • s
C) 6.8*10^-4 mol/L • s
D) 1.7* 10^-6 mol/L • s
E) none of these

Question 36

Tabulated below are initial rate data for the reaction 2Fe(CN)₆^3- + 2I^- $\rightarrow$ 2Fe(CN)₆^4- + I₂ What is the experimental rate law?

A) k[Fe(CN)₆^3-][I^-]²
B) k[Fe(CN)₆^3-][I^-] [Fe(CN)₆^4-]
C) k[Fe(CN)₆^3-]²[I^-]
D) k[Fe(CN)₆^3-]²[I^-]²[Fe(CN)₆^4-]²[I₂]
E) k[Fe(CN)₆^3-]²[I^-][Fe(CN)₆^4-][I₂]

Question 37

Two isomers (A andB) of a given compound dimerize as follows:
Both processes are known to be second order in reactant, and k₁ is known to be 0.25 L/mol • s at 25° C, where

In a particular experiment, A and B were placed in separate containers at 25° C, where [A]₀ = 1.0 * 10^-2 M and [B]₀ = 2.5 *10^-2 M. It was found that [A] = 3[B] after the reactions progressed for 3.0 min.
Calculate the half-life for the reaction involving A.

A) 4.0 * 10² s
B) 1.8 *10² s
C) 2.5 * 10³
D) 1.7 * 10¹ s

Question 38

The decomposition of N₂O₅(g) to NO₂(g) and O₂(g) obeys first-order kinetics. Assume the form of the rate law is
Rate where k = 3.4 *10^-5 s^-1 at 25°C.

-What is the half-life for the reaction described?

A) 2.4 * 10^-5 s
B) 7.4 *10² s
C) 5.9 * 10⁵ s
D) 2.0 *10⁴ s
E) none of these

Question 39

The reaction
H₂SeO₃(aq) + 6I^-(aq) + 4H⁺(aq) $\rightarrow$ 2I₃^-(aq) + 3H₂O(l) + Se(s)
was studied at 0°C by the method of initial rates:

-What is the numerical value of the rate constant?

A) 4.2
B) 2.1 * 10²
C) 5.2 * 10⁵
D) 1.9 * 10^-6
E) none of these

Question 40

The reaction A $\rightarrow$ B + C is known to be zero order in A with a rate constant of 3.8 *10^-2 mol/L • s at 25° C. An experiment was run at 25°C where [A]₀ = 2.2 *10^-3 M. What is the rate after 6.8 minutes?

A) 2.2 *10^-3 mol/L • s
B) 3.8 * 10^-2 mol/L • s
C) 8.4 *10^-5 mol/L • s
D) 8.1 *10^-4 mol/L • s
E) 1.5 *10^-11 mol/L • s

Question 41

For the reaction aA $\rightarrow$ products, select the reaction order(s) that best fit(s) the observations.

-The half-life is constant.

A) zero order in A
B) second order in A
C) first order in A
D) all of these
E) none of these

Question 42

For the reaction aA $\rightarrow$ products, select the reaction order(s) that best fit(s) the observations.

-A plot of [A]² vs. t gives a straight line.

A) zero order in A
B) second order in A
C) first order in A
D) all of these
E) none of these

Question 43

The reaction
2NOBr $\rightarrow$ 2NO + Br₂
exhibits the rate law
Rate = k[NOBr]² where k = 1.0 *10^-5 M^-1 • s^-1 at 25° C. This reaction is run where the initial concentration of NOBr ([NOBr]₀) is 1.00 * 10^-1 M.

-What is one half-life for this experiment?

A) 1.0 * 10⁶ s
B) 6.9 * 10⁴ s
C) 5.0 * 10^-1 s
D) 1.0 *10^-5 s
E) none of these

Question 44

For a reaction aA $\rightarrow$ products, [A]₀ = 4.0 M, and the first three successive half-lives are 48, 96, and 192 min.

-Calculate [A] at t = 81 min.

A) 2.6 M
B) 3.0 M
C) 1.3 M
D) 1.5 M
E) none of these

Question 45

The reaction
2NOBr $\rightarrow$ 2NO + Br₂
exhibits the rate law
Rate = k[NOBr]² where k = 1.0 *10^-5 M^-1 • s^-1 at 25° C. This reaction is run where the initial concentration of NOBr ([NOBr]₀) is 1.00 * 10^-1 M.

-The [NO] after 1.00 h has passed is

A) 9.7 * 10^-3 M
B) 9.9*10^-3 M
C) 1.0 * 10^-3 M
D) 3.5 * 10^-4 M
E) none of these

Question 46

For a reaction aA $\rightarrow$ products, [A]₀ = 4.0 M, and the first three successive half-lives are 48, 96, and 192 min.

-Calculate k (without units).

A) 5.2 * 10^-3
B) 1.4 * 10^-2
C) 2.6*10^-3
D) 4.1*10^-3
E) none of these

Question 47

For the reaction 2N₂O₅(g) $\rightarrow$ 4NO₂(g) + O₂(g), the following data were collected.

-The concentration of O₂ at t = 10. min is

A) 0.32 * 10^-2 mol/L
B) 2.0 * 10^-4 mol/L
C) 0.64 * 10^-2 mol/L
D) 0.16 *10^-2 mol/L
E) none of these

Question 48

For the reaction aA $\rightarrow$ products, select the reaction order(s) that best fit(s) the observations.

-The half-life decreases over time.

A) second order in A
B) first order in A
C) zero order in A
D) all of these
E) none of these

Question 49

For the reaction aA $\rightarrow$ products, select the reaction order(s) that best fit(s) the observations.

-The reaction A $\rightarrow$ B + C is known to be zero order in A with a rate constant of 5.4 * 10^-2 mol/L • s at 25° C. An experiment was run at 25°C where [A]₀ = 3.0 *10^-3 M. What is the half-life for the reaction?

A) 1.3 * 10¹ s
B) 2.7 * 10^-2 s
C) 8.1 *10^-2 s
D) 6.2* 10⁴ s
E) 2.8 * 10^-2 s

Question 50

For the reaction aA $\rightarrow$ products, select the reaction order(s) that best fit(s) the observations.

-[A] is constant.

A) zero order in A
B) second order in A
C) first order in A
D) all of these
E) none of these

Question 51

For a reaction aA $\rightarrow$ products, [A]₀ = 4.0 M, and the first three successive half-lives are 48, 96, and 192 min.

-The reaction 2NO $\rightarrow$ N₂ + O₂ has the following rate law: After a period of 2.0 * 10³ s, the concentration of NO falls from an initial value of 2.8 *10^-3 mol/L to 2.0* 10^-4 mol/L. What is the rate constant, k?

A) 4.0 *10^-4 M^-1/s
B) 7.2 * 10^-2 M^-1/s
C) 1.7 *10^-4 M^-1/s
D) 4.0 *10^-7 M^-1/s
E) 3.6 * 10^-2 M^-1/s

Question 52

For the reaction aA $\rightarrow$ products, select the reaction order(s) that best fit(s) the observations.

-A plot of [A] vs. t is a straight line.

A) zero order in A
B) second order in A
C) first order in A
D) all of these
E) none of these

Question 53

For the reaction aA $\rightarrow$ products, select the reaction order(s) that best fit(s) the observations.

-The rate is constant over time.

A) zero order in A
B) first order in A
C) second order in A
D) all of these
E) none of these

Question 54

For the reaction 2N₂O₅(g) $\rightarrow$ 4NO₂(g) + O₂(g), the following data were collected.

-The concentration N₂O₅ at 100 min will be approximately

A) 0.10*10^-2 mol/L
B) 0.01 *10^-2 mol/L
C) 0.06 * 10^-2 mol/L
D) 0.03 *10^-2 mol/L
E) none of these

Question 55

For the reaction 2N₂O₅(g) $\rightarrow$ 4NO₂(g) + O₂(g), the following data were collected.

-The order of this reaction in N₂O₅ is

A) 0
B) 1
C) 2
D) 3
E) none of these

Question 56

For the reaction aA $\rightarrow$ products, select the reaction order(s) that best fit(s) the observations.

-For which order reaction is the half-life of the reaction proportional to 1/k (k is the rate constant)?

A) second order
B) zero order
C) first order
D) all of these
E) none of these

Question 57

For the reaction aA $\rightarrow$ products, select the reaction order(s) that best fit(s) the observations.

-A plot of k vs. 1/T gives a straight line.

A) first order in A
B) zero order in A
C) second order in A
D) all of these
E) none of these

Question 58

If the reaction 2HI $\rightarrow$ H₂ + I₂ is second order, which of the following will yield a linear plot?

A) log [HI] vs. time
B) [HI] vs. time
C) ln [HI] vs. time
D) 1/[HI] vs. time

Question 59

The following question refers to the gas-phase decomposition of chloroethane: C₂H₅Cl $\rightarrow$ products
Experiment shows that the decomposition is first order. The following data show kinetics information for this reaction. What is the rate constant for this decomposition?

A) 0.22/s
B) 0.35/s
C) 0.29/s
D) 0.02/s
E) 0.11/s

Question 60

For the reaction 2N₂O₅(g) $\rightarrow$ 4NO₂(g) + O₂(g), the following data were collected.

-The half-life of this reaction is approximately

A) 18 min
B) 36 min
C) 15 min
D) 23 min
E) 45 min

Question 61

Calculate the value of k₂ where Rate = k₂[B]²

A) 0.75 L/mol • s
B) 2.2 L/mol • s
C) 0.21 L/mol • s
D) 1.9 L/mol • s
E) none of these

Question 62

Consider the reaction 3A + B + C $\rightarrow$ D + E
Where the rate law is defined as An experiment is carried out where [B]₀ = [C]₀ = 1.00 M and [A]₀ = 2.46 *10^-4 M. After 2.96 min, [A] = 3.30 *10^-5 M. What is the value of k?

A) 8.34 *10⁷ L³/mol³ • s
B) 4.00* 10^-7 L³/mol³ • s
C) 2.13 * 10^-5 L³/mol³ • s
D) 1.48 * 10² L³/mol³ • s
E) 8.86 *10³ L³/mol³ • s

Question 63

The following questions refer to the gas-phase decomposition of chloroethane:
C₂H₅Cl $\rightarrow$ products
Experiment shows that the decomposition is first order. The following data show kinetics information for this reaction.

-What would the concentration be after 5.0 s?

A) 0.08 M
B) 0.02 M
C) 0.12 M
D) 0.13 M
E) 0.19 M

Question 64

Consider the reaction
3A + B + C $\rightarrow$ D + E
where the rate law is defined as k[A]²[B][C]
An experiment is carried out where [B]₀ = [C]₀ = 1.00 M and [A]₀ = 1.00 * 10^-4 M.

-What is the concentration of C after 10.0 min?

A) 0.330 M
B) 1.10 * 10^-5 M
C) 1.00 M
D) 0.100 M
E) none of these

Question 65

In 6 M HCl, the complex ion Ru(NH₃)₆³⁺ decomposes to a variety of products. The reaction is first order in Ru(NH₃)₆³⁺ and has a half-life of 14 h at 25°C. Under these conditions, how long will it take for the [Ru(NH₃)₆³⁺] to decrease to 53.0% of its initial value?

A) 6.6 h
B) 15 h
C) 5.6 h
D) 13 h
E) 7.4 h

Question 66

The reaction 2NO₂ $\rightarrow$ 2NO + O₂ obeys the rate law 1.40 * 10^-2 [NO₂]² at 500° K. If the initial concentration of NO₂ is 1.00 M, how long will it take for the [NO₂] to decrease to 25.0% of its initial value?

A) 71.4 s
B) 214 s
C) 49.5 s
D) 1.40 *10^-2 s
E) cannot be determined from these data

Question 67

Consider the reaction 3A + B + C $\rightarrow$ D + E
Where the rate law is defined as (1.66 * 10² L³/mol³ • s)[A]²[B][C]
An experiment is carried out where [B]₀ = [C]₀ = 1.00 M and [A]₀ = 2.72 * 10^-4 M. What is the half-life for this experiment?

A) 1.36 * 10^-5 s
B) 4.17 * 10^-3 s
C) 1.66 * 10² s
D) 8.19 *10^-7 s
E) 2.21 *10¹ s

Question 68

Consider the reaction
3A + B + C $\rightarrow$ D + E
where the rate law is defined as k[A]²[B][C]
An experiment is carried out where [B]₀ = [C]₀ = 1.00 M and [A]₀ = 1.00 * 10^-4 M.

-What is the concentration of A after 10.0 min?

A) 9.80*10^-6 M
B) 2.38*10^-6 M
C) 1.27 *10^-5 M
D) 1.06 *10^-9 M
E) none of these

Question 69

At a particular temperature, the half-life of a zero-order reaction is 21.0 min. How long will it take for the reactant concentration to be depleted by a factor of 8?

A) 63.0 min
B) 42.0 min
C) 36.8 min
D) 168 min
E) 147 min

Question 70

The following questions refer to the gas-phase decomposition of chloroethane:
C₂H₅Cl $\rightarrow$ products
Experiment shows that the decomposition is first order. The following data show kinetics information for this reaction.

-What was the initial concentration of the ethylene chloride?

A) 0.02 M
B) 0.22 M
C) 0.35 M
D) 0.29 M
E) 0.11 M

Question 71

The elementary chemical reaction O + ClO $\rightarrow$ Cl + O₂
Is made pseudo-first order in oxygen atoms by using a large excess of ClO radicals. The rate constant for the reaction is 3.5 *10^-11 cm³/molecule • s. If the initial concentration of ClO is 1.0 *10¹¹ molecules/cm³, how long will it take for the oxygen atoms to decrease to 10.% of their initial concentration?

A) 3.2 *10^-3 s
B) 0.66 s
C) 0.017 s
D) 23 s
E) 2.4 s

Question 72

The following data were collected for the decay of HO₂ radicals. Which of the following statements is true?

A) The half-life of the reaction is 2 ms.
B) A plot of 1/[HO₂] versus time gives a straight line.
C) The rate of the reaction increases with time.
D) The decay of HO₂ occurs by a first-order process.
E) A plot of ln [HO₂] versus time is linear with a slope of -k.

Question 73

The reaction 3NO $\rightarrow$ N₂O + NO₂
Is found to obey the rate law Rate = k[NO]². If the first half-life of the reaction is found to be 4.6 s, what is the length of the fourth half-life?

A) 28 s
B) 8.6 s
C) 69 s
D) 18 s
E) 74 s

Question 74

Two isomers (A and B) of a given compound dimerize as follows: Both processes are known to be second order in reactant, and k₁ is known to be 0.25 L/mol • s at 25° C, where
Rate = k₁[A]²
In a particular experiment, A and B were placed in separate containers at 25° C, where [A]₀ = 1.0 * 10^-2 M and [B]₀ = 2.5 * 10^-2 M. It was found that [A] = 3[B] after the reactions progressed for 3.0 min.

-Calculate the concentration of A₂ after 3.0 min.

A) 3.1 * 10^-3 M
B) 6.9 * 10^-3 M
C) 1.6* 10^-3 M
D) 2.8 * 10^-22 M
E) none of these

Question 75

At a particular temperature, N₂O₅ decomposes according to a first-order rate law with a half-life of 3.0 s. If the initial concentration of N₂O₅ is 1.0 *10¹⁶ molecules/cm³, what will be the concentration in molecules/cm³ after 10.0 s?

A) 6.3 * 10³
B) 9.9 * 10¹⁴
C) 9.4 *10²
D) 7.3 * 10⁹
E) 1.8 *10¹²

Question 76

At 760 K, acetaldehyde decomposes to carbon monoxide and methane: CH₃CHO $\rightarrow$ CH₄ + CO
A plot of ln [CH₃CHO] versus time is linear. After 530 s, [CH₃CHO] decreases to one half of its initial value of 0.10 M. What is the rate law for the reaction?

A)
B)
C)
D)
E)

Question 77

The reaction 2N₂O₅(g) $\rightarrow$ O₂(g) + 4NO₂(g)
Is first order in N₂O₅. For this reaction at 45° C, the rate constant k = 1.0 * 10^-5 s^-1, where the rate law is defined as
Rate For a particular experiment ([N₂O₅]₀ = 1.0 *10^-3 M), calculate [N₂O₅] after 1.0 * 10⁵ s.

A) 0
B) 5.0*10^-4 M
C) 3.7 * 10^-4 M
D) 1.0*10^-3 M
E) none of these

Question 78

For a reaction aA $\rightarrow$ products, [A]₀ = 4.0 M, and the first three successive half-lives are 48, 96, and 192 min.

-The reaction A $\rightarrow$ B + C is known to be zero order in A with a rate constant of 4.2 *10^-2 mol/L • s at 25° C. An experiment was run at 25°C where [A]₀ = 1.8 M. What is the concentration of B after 5.4 s?

A) 1.6 M
B) 5.2 * 10^-1 M
C) 1.8 M
D) 2.3 *10^-1 M
E) 1.0 * 10^-1 M

Question 79

Consider the second-order reaction aA $\rightarrow$ products (which has a first half-life of 24 s). If the concentration of A after 15.4 s is 0.40 M, determine the initial concentration of A.

A) 0.66 M
B) 0.30 M
C) 0.61 M
D) 0.15 M
E) 0.20 M

Question 80

The following questions refer to the gas-phase decomposition of chloroethane:
C₂H₅Cl $\rightarrow$ products
Experiment shows that the decomposition is first order. The following data show kinetics information for this reaction.

-What is the time to half-life?

A) 8.9 s
B) 0.7 s
C) 6.3 s
D) 1.3 s
E) 2.2 s