Kinetics Problems

Name: ________________________ Class: ___________________ Date: __________ ID: A

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Kinetics Practice questions

Multiple ChoiceIdentify the choice that best completes the statement or answers the question.

____ 1. Rate constants usuallya. decrease with time. b. increase with time. c. decrease with temperature. d. increase with temperature. e. are independent of time and temperature.

____ 2. Which of the statements concerning relative rates of reaction is correct for the decomposition of dinitrogen pentaoxide?

2 N2O5(g) → 4 NO2(g) + O2(g)

a. The rate of disappearance of N2O5 is 1/2 the rate of appearance of O2. b. The rate of appearance of NO2 is 1/4 the rate of appearance of O2. c. The rate of disappearance of N2O5 is 1/2 the rate of appearance of NO2. d. The rate of appearance of NO2 equals the rate of appearance of O2. e. The rate of disappearance of N2O5 equals the rate of appearance of NO2.

____ 3. Which of the following relationships are correct for the reaction of peroxydisulfate ion with iodide ion?

S2O82-(aq) + 3 I-(aq) → 2 SO4

2-(aq) + I3-(aq)

a. Δ[I−]

Δt= −

Δ[I3−]

Δt b. −3

Δ[I−]Δt

Ê

Ë

ÁÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃̃ =

Δ[I3−]

Δt c. −3

Δ[I−]Δt

Ê

Ë

ÁÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃̃ = 2

Δ[SO42 −]

Δt

Ê

Ë

ÁÁÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃̃˜ d. 3

Δ[I−]Δt

Ê

Ë

ÁÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃̃ =

Δ[S2 O82 −]

Δt

e. −13

Δ[I−]Δt

Ê

Ë

ÁÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃̃ =

12

Δ[SO42 −]

Δt

Ê

Ë

ÁÁÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃̃˜

____ 4. Which of the following expressions relates the rates of reaction of NO(g) and Cl2(g)

2 NOCl(g) → 2 NO(g) + Cl2(g)

a. 2Δ[NO]

Δt

Ê

Ë

ÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜

=Δ[Cl2 ]

Δt b.

12

Δ[NO]Δt

Ê

Ë

ÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜

=Δ[Cl2 ]

Δt c. −

12

ΔtΔ[NO]

Ê

Ë

ÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜

=Δ[Cl2 ]

Δt

d. −2Δt

Δ[NO]

Ê

Ë

ÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜

=Δt

Δ[Cl2 ] e. 2

ΔtΔ[NO]

Ê

Ë

ÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜

=Δ[Cl2 ]

Δt

____ 5. Ammonia can be formed by reacting nitrogen and hydrogen gases.

N2(g) + 3 H2(g) → 2 NH3(g)

If the rate of disappearance of hydrogen is -2.7 × 10-2 M/s, what is the rate of formation of ammonia?a. 1.8 × 10-2 M/s b. 2.7 × 10-2 M/s c. 4.0 × 10-2 M/s d. 5.4 × 10-2 M/s e. 8.1 × 10-2 M/s

Name: ________________________ ID: A

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____ 6. Given the initial rate data for the decomposition reaction,

A → 2B

determine the rate expression for the reaction.

[A], M -Δ[A]/Δt M/s0.125 5.14 × 102

0.175 1.01 × 103

0.250 2.06 × 103

a. −Δ[A]

Δt = 4.11 × 103[A] b.

−Δ[A]Δt

= 4.11 × 103[A]2 c. −Δ[A]

Δt = 3.29 × 104[A]2 d.

−Δ[A]Δt

= 5.14 × 102

e. −Δ[A]

Δt = 3.29 × 104[A]

____ 7. Given the initial rate data for the reaction A + B → C, determine the rate expression for the reaction.

[A], M [B], M Δ[C]/Δt (initial) M/s0.10 0.20 4.20 × 10-4

0.10 0.40 1.68 × 10-3

0.20 0.40 3.36 × 10-3

a. Δ[C]

Δt = 0.105[A][B]2 b.

Δ[C]Δt

= 0.0210[A][B]2 c. Δ[C]

Δt = 0.0210[A]2[B] d.

Δ[C]Δt

= 0.105[A][B]

e. Δ[C]

Δt = 0.105[A]2[B]

____ 8. Given the initial rate data for the reaction A + B → C, determine the rate expression for the reaction.

[A], M [B], M Δ[C]/Δt (initial) M/s0.25 0.15 1.23 × 10-3

0.25 0.25 3.42 × 10-3

0.50 0.15 2.46 × 10-3

a. Δ[C]

Δt = 0.0328[A][B] b.

Δ[C]Δt

= 0.0547[A][B] c. Δ[C]

Δt = 0.219[A][B]2 d.

Δ[C]Δt

= 0.0547[A][B]2

e. Δ[C]

Δt = 0.219[A]2[B]

Name: ________________________ ID: A

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____ 9. Given the initial rate data for the reaction A + B → C, determine the rate expression for the reaction.

[A], M [B], M Δ[C]/Δt (initial) M/s0.125 0.105 1.23 × 10-1

0.125 0.315 3.69 × 10-1

0.250 0.105 1.23 × 10-1

a. Δ[C]

Δt = 75.0[A]2[B] b.

Δ[C]Δt

= 1.17[B] c. Δ[C]

Δt = 1.17[A]2[B] d.

Δ[C]Δt

= 11.2[B]2 e. Δ[C]

Δt =

11.2[A]

____ 10. What is the overall order of the reaction

CO(g) + NO2(g) → CO2(g) + NO(g)

if it proceeds via the following rate expression?

Δ[CO2 ]

Δt = k[CO][NO2]

a. zero-order b. first-order c. second-order d. third-order e. fourth-order

____ 11. Nitric oxide reacts with hydrogen at a measurable rate at 1000 K according to the equation below.

2 NO(g) + 2 H2(g) → N2(g) + 2 H2O(g)

What is overall order of the reaction?a. first-order b. second-order c. third-order d. fourth-order e. not enough information given to solve

____ 12. For the reaction A + B → C, the rate law is

Δ[C]Δt

= k[A][B]

What are the units of the rate constant where time is measured in seconds?

a. 1

M • s b.

1M2 • s

c. M • S d. M2

s e.

Ms

____ 13. For the reaction A → B, the rate law is

Δ[B]Δt

= k[A]

What are the units of the rate constant where time is measured in seconds?

a. 1

M • s b. M • s c.

sM

d. M2

s e.

1s

Name: ________________________ ID: A

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____ 14. Which of the following factors often affect the value of the rate constant of a chemical reaction?

1. changes in the concentrations of reactants2. changes in the temperature of the system3. the addition of a catalysta. 1 only b. 2 only c. 3 only d. 2 and 3 e. 1, 2, and 3

____ 15. The reaction of NO(g) and O2(g) produces NO2(g).

2 NO(g) + O2(g) → 2 NO2(g)

The reaction is second-order with respect to NO(g) and first-order with respect to O2(g). At a given temperature, the rate constant, k, equals 5.7 × 103 M-2s-1. What is the rate of reaction when the initial concentrations of NO and O2 are both 0.020 M?a. 1.4 × 10-9 M/s b. 4.6 × 10-2 M/s c. 9.1 × 10-2 M/s d. 2.3 × 100 M/s e. 7.1 × 108 M/s

____ 16. What determines the exponents in a rate law?

1. experimentation2. the coefficients in the balanced equation3. the concentrations of the reactants

a. 1 only b. 2 only c. 3 only d. 1 and 2 e. 2 and 3

____ 17. For a second-order decomposition reaction,

2A → B rate = k[A]2

which of the following can be plotted versus time to give a straight line?

a. [A] b. ln[A] c. ln1

[A] d.

1[A]

e. 1

[A]2

____ 18. A student analyzed a first-order reaction and obtained the graph below. Unfortunately, the student forgot to label the axes. What are the correct labels for the X and Y axes?

a. X = time, Y = ln[A] b. X = time, Y = 1/[A] c. X = time, Y = ln(1/[A]) d. X = 1/time, Y = [A] e. X = 1/time, Y = 1/[A]

____ 19. Which of the following equations corresponds to the integrated expression for a first-order decomposition reaction?

a. [A] = -kt + [A]0 b. 1n[A] = -kt + 1n[A]0 c. 1

[A] = kt +

1[A]0

d. [A][A]0

= -kt e. [A]0

[A] = -kt

Name: ________________________ ID: A

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____ 20. The half-life of a first-order decomposition reaction is 188 seconds. If the initial concentration of reactant is 0.524 M, what is the concentration of reactant after 752 seconds?a. 0.0164 M b. 0.0328 M c. 0.0665 M d. 0.133 M e. 0.266 M

____ 21. What is the rate constant for a first-order reaction if the half-life of the reaction is 0.819 seconds?a. 0.0998 s-1 b. 0.812 s-1 c. 0.846 s-1 d. 1.18 s-1 e. 2.44 s-1

____ 22. Which of the following equations corresponds to the integrated expression for a second-order decomposition reaction?

a. [A] = -kt + [A]0 b. 1n[A] = -kt + 1n[A]0 c. 1

[A] = kt +

1[A]0

d. [A][A]0

= -kt e. [A]0

[A] = -kt

____ 23. For the first-order decomposition of N2O5 at 340 K, where k = 5.8 × 10-3 s-1, calculate the concentration after 455 seconds if the initial concentration is 0.380 M.a. 0.0071 M b. 0.0087 M c. 0.011 M d. 0.019 M e. 0.027 M

____ 24. The reaction A → B follows first-order kinetics with k = 0.032 s-1. If the concentration of A is 0.434 M after 14.5 seconds, what is the initial concentration of A?a. 0.464 M b. 0.690 M c. 1.45 M d. 1.59 M e. 3.66 M

____ 25. Hydrogen peroxide decays into water and oxygen in a first-order process.

H2O2(aq) → H2O(™) + 1/2 O2(g)

At 20.0°C, the half-life for the reaction is 3.92 × 104 seconds. If the initial concentration of hydrogen peroxide is 1.5 M, what is the concentration after 7.0 days?a. 3.4 × 10-5 M b. 0.0088 M c. 0.039 M d. 0.48 M e. 1.2 M

____ 26. The decomposition of HCO2H follows first-order kinetics.

HCO2H(g) → CO2(g) + H2(g)

The half-life for the reaction at 550ºC is 24 seconds. How many seconds are needed for the formic acid concentration to decrease by 33%?a. 7.9 s b. 14 s c. 16 s d. 17 s e. 21 s

____ 27. The decomposition of phosphine, PH3, follows first-order kinetics.

4 PH3(g) → P4(g) + 6 H2(g)

The half-life for the reaction at 550ºC is 81.3 seconds. How long does it take for 99% of a phosphine sample to decompose?a. 9.2 × 10-4 s b. 8.5 × 10-3 s c. 5.7 × 10-2 s d. 8.5 × 10-1 s e. 5.4 × 102 s

____ 28. What is the half-life of a first-order reaction if it takes 298 seconds for the concentration to decrease from 2.20 M to 0.32 M?a. 4.9 × 10-4 s b. 6.5 × 10-3 s c. 9.3 × 10-3 s d. 1.5 × 101 s e. 1.1 × 102 s

____ 29. What is the half-life for a first-order reaction with a rate constant of 0.291 s-1?a. 0.202 s b. 0.420 s c. 2.38 s d. 3.44 s e. 4.96 s

Name: ________________________ ID: A

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____ 30. For the second-order reaction below, the concentration of the product, B, after 539 seconds is 0.0811 M. If no B is initially present, and the initial concentration of A is 0.744 M, what is the rate constant?

2A → B rate = k[A]2

a. 8.16 × 10-5 M-1s-1 b. 3.05 × 10-4 M-1s-1 c. 6.95 × 10-4 M-1s-1 d. 8.94 × 10-3 M-1s-1 e. 2.04 × 10-2 M-1s-1

____ 31. For the second-order reaction below, the initial concentration of reactant A is 0.24 M. If the rate constant for the reaction is 8.1 × 10-2 M-1s-1, what is the concentration of A after 29 seconds?

2A → B + C rate = k[A]2

a. 0.060 M b. 0.15 M c. 0.21 M d. 0.31 M e. 0.47 M

____ 32. Which of the following equations correctly describes the half-life for a zero-order reaction?

a. t1/2 = [A]2k

b. t1/2 = 2k

[A]0

c. t1/2 = k

2[A]0

d. t1/2 = 2

k[A]0

e. t1/2 = ln(2)

k[A]0

____ 33. For the zero-order reaction below, a graph of ________ versus time will generate a straight line.

A → B + C rate = k[A]0

a.1

[A]

b.1

[A]2

c. ln[A]

d. [A]

e.1n(2)[A]

____ 34. Which of the following changes generally lead to greater reaction rates?

1. Increasing the temperature2. Decreasing the concentration of a reactant3. Adding a catalyst

a. 1 only b. 2 only c. 1 and 3 d. 2 and 3 e. 1,2, and 3

____ 35. In general, as the temperature increases, the rate of a chemical reactiona. decreases due to fewer collisions with proper molecular orientation. b. decreases for endothermic reactions. c. decreases for exothermic reactions. d. increases due a greater number of effective collisions. e. increases due to a lowering of activation energy.

Name: ________________________ ID: A

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____ 36. The Arrhenius equation, k = Ae-E a/RT

, may be used to calculate the activation energy of a reaction. Which plot will generate a straight line with a slope of -Ea/R?a. k versus T b. ln(k) versus 1/T c. ln(k) versus ln(T) d. k versus 1/T e. 1/k versus ln(T)

____ 37. For a chemical reaction, the activation energy for the forward reaction is +215 kJ and the activation energy for the reverse reaction is +59 kJ. What is the overall energy change for the forward reaction?a. -274 kJ b. -156 kJ c. +156 kJ d. +215 kJ e. +274 kJ

____ 38. Calculate the activation energy, Ea for

N2O5(g) → 2 NO2(g) + 1/2 O2(g)

given k (at 25ºC) = 3.46 × 10-5 s-1 and k (at 35ºC) = 1.48 × 10-4 s-1.a. 1.06 kJ/mol b. 52.1 kJ/mol c. 89.9 kJ/mol d. 111 kJ/mol e. 326 kJ/mol

____ 39. For a given reaction, the rate constant triples when the temperature is increased from 25ºC to 45ºC. What is the activation energy for this reaction?a. 43.3 kJ/mol b. 118 kJ/mol c. 0.514 kJ/mol d. 29.1 kJ/mol e. 791 kJ/mol

____ 40. For a given reaction, the activation energy is 19.0 kJ/mol. If the reaction rate constant is 8.30 × 10-3 M-1s-1 at 298 K, what is the reaction rate constant at 348 K?a. 8.31 × 10-3 M-1s-1 b. 1.45 × 10-2 M-1s-1 c. 2.50 × 10-2 M-1s-1 d. 5.93 × 10-2 M-1s-1 e. 4.21 × 10-1 M-1s-1

____ 41. The rate constant at 325 K for a certain reaction is 8.11 × 10-3 s-1 and the activation energy is 9.53 kJ/mol. What is the value of the frequency factor, A, in the Arrhenius equation?a. 2.38 × 10-4 b. 2.66 × 10-3 c. 6.88 × 10-3 d. 2.76 × 10-1 e. 4.93 × 103

____ 42. The effect of a catalyst is toa. lower the activation energy of a reaction. b. increase the energy of the products. c. increase the energy of the reactants. d. increase the number of collisions between reactants. e. decrease the change in enthalpy of a reaction.

____ 43. The elementary steps for the catalyzed decomposition of dinitrogen monoxide are shown below. Identify the catalyst in the reaction.

N2O(g) + NO(g) → N2(g) + NO2(g)2 NO2(g) → 2 NO(g) + O2(g)a. N2 b. NO c. N2O d. NO2 e. O2

____ 44. In basic solution, (CH3)3CCl reacts according to the equation below.

(CH3)3CCl + OH- → (CH3)3COH + Cl-

The accepted mechanism for the reaction is

(CH3)3CCl → (CH3)3C+ + Cl- (slow)(CH3)3C+ + OH- → (CH3)3COH (fast)

What is the rate law for the reaction?a. rate = k[(CH3)3CCl] b. rate = k[(CH3)3CCl]2 c. rate = k[(CH3)3C+][OH-] d. rate = k[(CH3)3CCl][OH] e. rate = k[(CH3)3CCl][Cl-][OH-]

Name: ________________________ ID: A

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____ 45. Nitrogen monoxide reacts with chlorine to produce NOCl.

2 NO(g) + Cl2(g) → 2 NOCl(g)

A proposed mechanism for this reaction is

NO(g) + NO(g) N2O2(g) (fast, equilibrium)N2O2(g) + Cl2(g) → 2 NOCl(g) (slow)

What is a rate law that is consistent with this mechanism?a. rate = k[NO][Cl2] b. rate = k[[NO]2 c. rate = k[N2O2][Cl2] d. rate = k[NO][Cl2]2 e. rate = k[NO]2[Cl2]

____ 46. Which of the following is a kinetic quantity?a. enthalpy b. internal energy c. free energy d. rate of reaction e. entropy

____ 47. Of the following questions, which ones are thermodynamic rather than kinetic concepts?

I. Can substances react when they are put together?II. If a reaction occurs, how fast will it occur?III. What is the mechanism by which the reaction occurs?IV. If substances react, what energy changes are associated with the reaction?

a. I and III b. II and IV c. I and IV d. II and III e. I, III, and IV

____ 48. Which of the following expressions does not represent a proper expression for the rate of this reaction?

2A + 3B → F + 2G

a. −Δ[A]

Δt b. −Δ[B]

3Δt c. Δ[F]Δt d.

Δ[G]2Δt e.

−Δ[A]2Δt

____ 49. One of the reactions that is used to produce gaseous hydrogen commercially follows. A proper expression for the rate of this reaction could be __________.

H2O(g) + CO(g) → H2(g) + CO2(g)

a. −Δ[CO2]

Δt b. −Δ[H2 ]

Δt c. k d. Δ[CO]

Δt e. −Δ[H2 O]

Δt

____ 50. In the following reaction, the rate of formation of NH3 is 0.15 mol/L•min. What is the rate of reaction?

N2 + 3H2 → 2NH3

a. 0.15 mol/L•min b. 0.075 mol/L•min c. -0.075 mol/L•min d. 0.20 mol/L•min e. 0.30 mol/L•min

Name: ________________________ ID: A

9

____ 51. At some time, the rate of formation of C is observed to be 0.036 mol/L•s for the reaction below. In order, what is the rate of change of A, the rate of change of B, the rate of change of D and the rate of reaction at this time (all given in mol/L•s)?

2A + 3B → 4C + 2D

a. 0.018, 0.027, 0.018, 0.0090 b. - 0.018, - 0.027, 0.018, 0.0090 c. - 0.072, - 0.048, 0.072, 0.144 d. - 0.036, - 0.036, 0.036, 0.0090 e. - 0.018, - 0.012, - 0.018, 0.018

____ 52. Consider the exothermic combustion of coal. Which of the following could increase the rate of reaction?a. using smaller pieces of coal b. increasing the concentration of oxygen c. lowering the temperature d. both (a) and (b) are correct e. choices (a), (b) and (c) are all correct

____ 53. Four of the following factors can affect the forward rate of a chemical reaction. Which one cannot affect this rate? (Note: the question refers to reaction rate, not equilibrium.)a. temperature b. concentration of reactants of the forward reaction c. presence of a catalyst d. removal of some of the products of the forward reaction e. physical state or state of subdivision of solid reactants

____ 54. Suppose a reaction A + B → C occurs at some initial rate at 25°C. Which response includes all of the changes below that could increase the rate of this reaction?

I. lowering the temperatureII. adding a catalystIII. increasing the initial concentration of B

a. I b. II c. III d. I and II e. II and III

____ 55. Which of the following reactions would be expected to be the slowest?a. Ag+(aq) + Cl-(aq) → AgCl(s) b. H+(aq) + OH-(aq) → H2O(l) c. CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) d. Pb2+(aq) + CrO4

2-(aq) → PbCrO4(s) e. H+(aq) + CN-(aq) → HCN(aq)

____ 56. Which is not an example of the effect of subdivision of the reactant on the rate of chemical reaction?a. Violent explosions that occur in grain elevators. b. A container of flammable liquid will burn on the surface but allowed to vaporize will burn explosively. c. A chunk of iron takes months to rust completely while iron wool will rust in days. d. Some metals may be fused (welded) with minimal loss while their powders will burn in a flame. e. The Grand Canyon was created by dissolution by water over millions of years.

____ 57. For a given reaction, the rate-law expression is __________.a. a constant of proportionality between reaction rate and the concentrations of reactants b. the sum of the powers to which reactant concentrations appear c. an equation in which reaction rate is equal to a mathematical expression involving, or related to, concentrations of reactants involved in the rate-determining step d. an equation that gives the additional energy that reactants must obtain in order to react e. 55 miles per hour

____ 58. Which of the following statements about reaction orders in the rate law expression is incorrect?a. Their values may equal the stoichiometric coefficients in the balanced equation. b. Their values may or may not equal the stoichiometric coefficients in the balanced equation. c. Their values must be experimentally determined. d. Their values get larger as the temperature is increased. e. An order equal to zero means there is no concentration dependence with rate.

Name: ________________________ ID: A

10

____ 59. The gas phase reaction A + B → C has a reaction rate which is experimentally observed to follow the relationship rate = k[A]2[B]. The overall order of the reactiona. is first. b. is second. c. is third. d. is zero. e. is one-half.

____ 60. The gas phase reaction A + B → C has a reaction rate which is experimentally observed to follow the relationship rate = k[A]2. The reaction is __________ order in B.a. first b. second c. third d. zero e. one-half

____ 61. The gas phase reaction A + B → C has a reaction rate which is experimentally observed to follow the relationship rate = k[A]2[B]. Which one of the following would affect the value of the specific rate constant, k?a. decreasing the temperature b. changing the concentration of A c. changing the concentration of B d. changing the concentration of C e. letting the reaction go on for a long time

____ 62. A hypothetical reaction X + 2Y → Products is found to be first order in X and second order in Y. What are the units of k, the specific rate constant, if reaction rate is expressed in units of moles per liter per second?a. M•s-1 b. M-2•s-1 c. M-3•s d. M2•s-1 e. M-1•s

____ 63. Which of the following statements regarding the rate constant in the rate law expression is incorrect?a. Its value increases with temperature. b. Its value is independent of initial concentration at a given temperature. c. Its units depend on the overall order of reaction. d. Its value is experimentally determined. e. The larger its value, the slower the reaction rate.

____ 64. The units of the rate constant for a second order reaction could be __________.a. M-1•s-1 b. M c. M•s-1 d. s-1 e. M2•s-1

____ 65. A reaction A + 2B → C is found to be first order in A and first order in B. What are the units of the rate constant, k, if the rate is expressed in units of moles per liter per minute?a. M-1•min-1 b. M c. M•min-1 d. min-1 e. M2•min-1

____ 66. Consider the following rate law expression: rate = k[A]2[B]. Which of the following is not true about the reaction having this expression?a. The reaction is first order in B. b. The reaction is overall third order. c. The reaction is second order in A. d. A and B must both be reactants. e. Doubling the concentration of A doubles the rate.

____ 67. Consider the following rate law expression: rate = k[A][B]. Which of the following is not true about the reaction having this expression?a. The reaction is first order in B. b. The reaction is overall second order. c. The reaction is first order in A. d. A and B must both be reactants. e. Doubling the concentrations of A and of B doubles the rate.

____ 68. The gas phase reaction A + B → C has a reaction rate which is experimentally observed to follow the relationship rate = k[A]2[B]. If the concentration of A is tripled and the concentration of B is doubled, the reaction rate would be increased by a factor of __________.a. 6 b. 9 c. 12 d. 18 e. 36

____ 69. The gas-phase reaction

2NO + 2H2 → N2 + 2H2O

has the following rate law expression, rate = k[NO]2[H2]. If the [NO] is halved and the [H2] is tripled, what change in rate is expected?a. decrease by 3/4 b. increase by 3/4 c. increase by 3/2 d. decrease by 3/2 e. stays same

Name: ________________________ ID: A

11

____ 70. A reaction is second order in X and zero order in Y. Doubling the initial concentration of X and halving the initial concentration of Y at constant temperature causes the initial rate toa. increase by a factor of 4. b. decrease by a factor of 2. c. remain unchanged. d. increase by a factor of 2. e. be undeterminable without the balanced equation.

____ 71. Consider the following rate data for the reaction below at a particular temperature.

2A + 3B → Products

Experiment Initial [A] Initial [B] Initial Rate of Loss of A1 0.10 M 0.30 M 7.20 × 10-5 M•s-1

2 0.10 M 0.60 M 1.44 × 10-4 M•s-1

3 0.20 M 0.90 M 8.64 × 10-4 M•s-1

The reaction is __________ order in A and __________ order in B.a. first, first b. second, first c. first, second d. second, second e. third, first

____ 72. Given the following data for the NH4+ + NO2

- → N2 + 2H2O reaction

Trial [NH4+] [NO2

-] Rate1 0.010 M 0.020 M 0.020 M/s2 0.015 0.020 0.0303 0.010 0.010 0.005

The rate law for the reaction isa. rate = k[NH4

+][NO2-] b. rate = k[NH4

+]2[NO2-] c. rate = k[NH4

+][NO2-]2 d. rate = k[NH4

+]2[NO2-]2

e. None of the above

____ 73. Determine the rate-law expression for the reaction below.

2A + B2 + C → Α2B + BC

Trial Initial [A] Initial [B2] Initial [C] Initial Rate of Formation of BC1 0.20 M 0.20 M 0.20 M 2.4 × 10-6 M•min-1

2 0.40 M 0.30 M 0.20 M 9.6 × 10-6 M•min-1

3 0.20 M 0.30 M 0.20 M 2.4 × 10-6 M•min-1

4 0.20 M 0.40 M 0.40 M 4.8 × 10-6 M•min-1

a. rate = k[A]2[B2][C] b. rate = k[B2]2[C]2 c. rate = k[A][C]2 d. rate = k[A]2[C] e. rate = k[A][B2][C]

Name: ________________________ ID: A

12

____ 74. Rate data have been determined at a particular temperature for the overall reaction2NO + 2H2 → Ν2 + 2H2O in which all reactants and products are gases.

Trial Run Initial [NO] Initial [H2] Initial Rate (M•s-1)1 0.10 M 0.20 M 0.01502 0.10 M 0.30 M 0.02253 0.20 M 0.20 M 0.0600

The rate-law expression is __________.a. rate = k[NO]2[H2]2 b. rate = k[NO][H2]2 c. rate = k[NO]2[H2] d. rate = k[NO][H2] e. None of the preceding answers is correct.

____ 75. A troublesome reaction that is responsible in part for acid rain is

SO3 + H2O → H2SO4

Rate data have been determined at a particular temperature for the reaction in which all reactants and products are gases.

Trial Run Initial [SO3] Initial [H2O] Initial Rate (M•s-1)1 0.35 M 0.35 M 0.1502 0.70 M 0.35 M 0.6003 0.35 M 0.70 M 0.3004 0.70 M 0.70 M 1.20

The rate-law expression is __________.a. rate = k[SO3]2[H2O]2 b. rate = k[SO3]2[H2O] c. rate = k[SO3][H2O]2 d. rate = k[SO3]2 e. rate = k[SO3][H2O]

____ 76. NO reacts with chlorine in a gas phase reaction to form nitrosyl chloride, NOCl. From the following experimental data, determine the form of the equation that describes the relationship of reaction rate to initial concentrations of reactants.

2NO + Cl2 → 2NOCl

Run Initial [NO] Initial [Cl2] Initial Rate of Formation of NOCl1 0.50 M 0.35 M 1.14 M/hr2 1.00 M 1.00 M 9.12 M/hr3 1.00 M 0.50 M 4.56 M/hr

a. rate = k[NO] b. rate = k[NO][Cl2] c. rate = k[NO]2 d. rate = k[NO]2[Cl2] e. rate = k[NO]2[Cl2]2

Name: ________________________ ID: A

13

____ 77. The following data were collected for the following reaction at a particular temperature. What is the rate-law expression for this reaction? rate = __________.

A + B → C

Experiment Initial [A] Initial [B] Initial Rate of Formation of C1 0.10 M 0.10 M 4.0 × 10-4 M/min2 0.20 M 0.20 M 3.2 × 10-3 M/min3 0.10 M 0.20 M 1.6 × 10-3 M/min

a. k[A] b. k[A]2 c. k[A][B] d. k[B] e. k[A][B]2

____ 78. The following data were collected for the following reaction at a particular temperature. What is the rate-law expression for this reaction? rate = __________.

NH3 + O2 → N2O + H2O

Experiment Initial [NH3] Initial [O2] Initial Rate1 1.10 M 1.10 M 5.5 × 10-3 M/s2 2.20 M 2.20 M 4.4 × 10-2 M/s3 1.10 M 2.20 M 2.2 × 10-2 M/s

a. k[NH3] b. k[NH3]2 c. k[NH3][ O2] d. k[O2] e. k[NH3][ O2]2

____ 79. Determine the rate-law expression for the reaction below at the temperature at which the tabulated initial rate data were obtained. rate = __________

A + 2B + 3C → Products

Experiement Initial [A] Initial [B] Initial [C] Initial Rage of Loss of A1 0.10 M 0.20 M 0.10 M 4.0 × 10-2 M•min-1

2 0.40 M 0.20 M 0.10 M 4.0 × 10-2 M•min-1

3 0.20 M 0.20 M 0.25 M 1.0 × 10-1 M•min-1

4 0.20 M 0.40 M 0.10 M 1.6 × 10-1 M•min-1

a. k[A][B] b. k[A]2[C] c. k[C]2 d. k[B]2[C] e. none of these

____ 80. Evaluate the specific rate constant for this reaction at 800°C. The rate-law expression is rate = k[NO]2[H2]. (Choose the closest answer.)

2NO(g) + 2H2(g) → Ν 2(g) + 2H2O(g)

Experiment Initial [NO] Initial [H2] Initial Rate of Reaction (M•s-1)1 0.0010 M 0.0060 M 7.9 × 10-7

2 0.0040 M 0.0060 M 1.3 × 10-5

3 0.0040 M 0.0030 M 6.4 × 10-6

a. 22 M-2•s-1 b. 4.6 M-2•s-1 c. 1.3 x 102 M-2•s-1 d. 0.82 M-2•s-1 e. 0.024 M-2•s-1

Name: ________________________ ID: A

14

____ 81. Evaluate the specific rate constant for the reaction at the temperature for which the data were obtained. The rate-law expression is rate = k[A][B]2.

A + B → C

Experiement Initial [A] Initial [B] Initial Rage of Formation of C1 0.10 M 0.10 M 4.0 × 10-4 M/min2 0.20 M 0.20 M 3.2 × 10-3 M/min3 0.10 M 0.20 M 1.6 × 10-3 M/min

a. 1.2 × 10-2 M-2•min-1 b. 3.6 × 10-2 M-2•min-1 c. 4.0 × 10-1 M-2•min-1 d. 6.2 × 10-1 M-2•min-1 e. 7.0 × 10-3 M-2•min-1

____ 82. Evaluate the specific rate constant at the temperature at which the data were collected. The rate-law expression is rate = k[NO]2[H2].

H2(g) + NO(g) → N2O(g) + H2O(g)

Experiement Initial [NO] (M) Initial [H2] (M) Initial Rate (M•s-1)1 0.30 0.35 2.835 × 10-3

2 0.60 0.35 1.134 × 10-2

3 0.60 0.70 2.268 × 10-2

a. 9.4 × 10-3 M-2•s-1 b. 2.7 × 10-2 M-2•s-1 c. 1.6 × 10-4 M-2•s-1 d. 8.1 × 10-3 M-2•s-1 e. 9.0 × 10-2 M-2•s-1

____ 83. Rate data have been determined at a particular temperature for the overall reaction

2NO + 2H2 → Ν2 + 2H2O in which all reactants and products are gases. The value of the specific rate constant at this temperature is __________.

Trial Run Initial [NO] Initial [H2] Initial Rate (M•s-1)1 0.10 M 0.20 M 0.01502 0.10 M 0.30 M 0.02253 0.20 M 0.20 M 0.0600

a. 0.75 M-1•s-1 b. 7.5 M-2•s-1 c. 3.0 × 10-3 M-2•s-1 d. 3.0 × 10-4 M-1•s-1 e. 375 M-2•s-1

____ 84. The following rate data apply to the reaction 3X + Y + 2Z → Products at a particular temperature. What is the value of k at this temperature?

Experiment Initial [X] Initial [Y] Initial [Z] Initial Rate of Loss of X1 0.300 M 0.200 M 0.100 M 6.40 × 10-3 M•min-1

2 0.300 0.300 0.250 4.00 × 10-2

3 0.600 0.300 0.250 4.00 × 10-2

4 0.900 0.200 0.400 1.02 × 10-1

5 0.800 0.400 0.100 6.40 × 10-3

a. 0.274 M-1•min-1 b. 0.341 M-1•min-1 c. 0.640 M-1•min-1 d. 0.890 M-1•min-1 e. 0.914 M-1•min-1

Name: ________________________ ID: A

15

____ 85. Consider a chemical reaction involving compounds A and B, which is found to be first order in A and second order in B. At what rate will the reaction occur in experiment 2?

Experiment Rate (M•s-1) Initial [A] Initial [B]1 0.10 1.0 M 0.20 M2 ? 2.0 M 0.60 M

a. 1.2 M•s-1 b. 0.20 M•s-1 c. 0.60 M•s-1 d. 1.8 M•s-1 e. 0.36 M•s-1

____ 86. The oxidation of NO by O3 is first order in each of the reactants, and its rate constant is 1.5 × 107 M-1•s-1. If the concentrations of NO and O3 are each 5.0 × 10-7 M, what is the rate of oxidation of NO in M•s-1?a. 3.8 × 10-6 b. 2.5 × 10-14 c. 7.5 × 10-7 d. 15 e. 7.5

____ 87. A bimolecular reaction is found to be 1st order with respect to both reactants. If the rate of reaction is 1.87 mol/L •s at 25°C, what is the reaction rate if both reactant concentrations are doubled?a. 7.48 mol/L •s b. 46.8 mol/L •s c. 1.87 mol/L •s d. 0.94 mol/L •s e. 3.74 mol/L •s

____ 88. Consider the hypothetical reaction and rate data below. Determine the form of the rate-law expression (i.e., determine the values of a and b in rate = k[A]a[B]b) and also the value of the specific rate constant, k. Which of the answers below would be the initial rate of reaction for [A]initial = 0.40 M and [B]initial = 0.10 M?

3A + 2B → Products

Run [A]initial [B]initial

Initial Rate of Reaction(moles per liter per second)

1 0.10 M 0.10 M 4.0 × 10-4

2 0.20 M 0.30 M 4.8 × 10-3

3 0.30 M 0.10 M 3.6 × 10-3

a. 1.6 × 10-4 M•s-1 b. 3.4 × 10-3 M•s-1 c. 1.2 × 10-3 M•s-1 d. 4.8 × 10-4 M•s-1 e. 6.4 × 10-3 M•s-1

____ 89. Rate data have been determined at a particular temperature for the overall reaction

2NO + 2H2 → Ν2 + 2H2Oin which all reactants and products are gases.

Trial Run Initial [NO] Initial [H2] Initial Rate (M•s-1)1 0.10 M 0.20 M 0.01502 0.10 M 0.30 M 0.02253 0.20 M 0.20 M 0.0600

What would be the initial rate of the reaction if the initial molar concentration of NO = 0.30 M and the initial molar concentration of H2 = 0.10 M?a. 0.068 M•s-1 b. 0.22 M•s-1 c. 0.022 M•s-1 d. 0.040 M•s-1 e. 0.10 M•s-1

Name: ________________________ ID: A

16

____ 90. What will be the initial rate of this reaction when [A] =0.60 M, [B] = 0.30 M, and [C] = 0.10 M? A + 2B + 3C → Products

Experiement Initial [A] Initial [B] Initial [C] Initial Rate of Loss of A1 0.10 M 0.20 M 0.10 M 4.0 × 10-2•M min-1

2 0.40 M 0.20 M 0.10 M 4.0 × 10-2•M min-1

3 0.20 M 0.20 M 0.25 M 1.0 × 10-1•M min-1

4 0.20 M 0.20 M 0.10 M 1.6 × 10-1•M min-1

a. 0.090 M•min-1 b. 4.0 M•min-1 c. 0.30 M•min-1 d. 0.40 M•min-1 e. 0.016 M•min-1

____ 91. The half-life for the reactant A in the first order reaction A → B is 36.2 seconds. What is the rate constant for this reaction at the same temperature?a. 52.2 s-1 b. 0.0276 s-1 c. 0.0191 s-1 d. 18.1 s-1 e. 0.00832 s-1

____ 92. The rate constant for the first order reaction A → B + C is k = 3.3 × 10-2 min-1 at 57 K. What is the half-life for this reaction at 57 K?a. 21 min b. 30 min c. 61 min d. 9.1 min e. 1200 min

____ 93. The rate constant for the second order reaction 2NO2 → N2O4 is 2.79 L/mol•min at 48 oC. If the initial concentration of NO2 is 1.05 M, what is the half-life?a. 20.5 s b. 10.3 s c. 0.341 min d. 176 s e. 14.9 s

____ 94. The half-life of the zero order reaction A → B is 0.56 minutes. If the initial concentration of A is 3.4 M, what is the rate constant?a. 6.07 mol/L •min b. 1.24 mol/L •min c. 3.04 mol/L •min d. 0.619 mol/L •min e. 1.79 mol/L •min

____ 95. The decomposition of dimethylether at 504°C is first order with a half-life of 1570. seconds. What fraction of an initial amount of dimethylether remains after 4710. seconds?a. 1/3 b. 1/6 c. 1/8 d. 1/16 e. 1/32

____ 96. The decomposition of dinitrogen pentoxide obeys the rate-law expression rate = 0.080 min-1[N2O5]. If the initial concentration of N2O5 is 0.30 M, what is the concentration after 2.6 minutes? N2O5 → N2O3 + O2

a. 0.38 M b. 0.028 M c. 0.24 M d. 0.13 M e. 0.32 M

____ 97. A chemical reaction A → B + C is first order in A and has a rate constant of 1.2 × 10-3 min-1. If the initial concentration of A is 0.40 M., how much time must pass in order to reduce the concentration of A to 0.22 M?a. 5.0 × 102 min b. 3.0 × 102 min c. 7.4 × 10-3 min d. 4.3 × 10-4 min e. 2.2 × 102 min

____ 98. The gas phase reaction below obeys the rate-law expression rate = k[SO2Cl2]. At 593 K the specific rate constant is 2.2 × 10-5 s-1. A 2.0-g sample of SO2Cl2 is introduced into a closed 4.0-L container.

SO2Cl2 → SO2 + Cl2

How much time must pass in order to reduce the amount of SO2Cl2 present to 1.8 grams?a. 7.4 × 103 seconds b. 2.1 × 102 seconds c. 3.5 × 102 seconds d. 4.8 × 103 seconds e. 5.8 × 104 seconds

Name: ________________________ ID: A

17

____ 99. The gas phase reaction below obeys the rate-law expression rate = k[PCl5]. At 400 K the specific rate constant is 0.0371 min-1. How many hours are required to reduce a sample of PCl5 to 10% of its original amount?

PCl5 → PCl3 + Cl2

a. 3.10 hrs b. 1.03 hrs c. 186 hrs d. 3.71 hrs e. 62 hrs

____ 100. Consider the following first order reaction. A2B → AB + AIf it takes 87 seconds for the concentration of A2B to be reduced from 2.2 M to 0.12 M, what is the value of the specific rate constant?a. 0.0334 min-1 b. 2.01 min-1 c. 2.01 s-1 d. 18.3 min-1 e. 3.51 × 10-3 s-1

____ 101. Cyclopropane rearranges to form propene in a reaction that is first order. If the rate constant is 2.74 × 10-3 s-1, how long would it take for 85.6% of the cyclopropane to rearrange if the initial concentration was 0.460 M?a. 51.0 s b. 62.0 s c. 707 s d. 2.74 × 10-3 s e. 3.83 × 10-4 s

____ 102. At 300 K the reaction below obeys the rate law Rate =k[NOCl]2 where k = 2.8 × 10-5 M-1•s-1.

2NOCl → 2NO + Cl2

Suppose 1.0 mole of NOCl is introduced into a 2.0-liter container at 300 K. Evaluate the half-life of the reaction.a. 2.6 × 103 seconds b. 3.6 × 104 seconds c. 2.4 × 104 seconds d. 1.1 × 103 seconds e. 4.0 × 104 seconds

____ 103. The second order reaction 2CH4 → C2H2 + 3H2

has a rate constant of 5.76 M-1•min-1 at 1600 K. How long would it take for the concentration of CH4 to be reduced from 0.89 M to 5.25 ×10-4 M?a. 165 hrs b. 0.15 hrs c. 2.75 hrs d. 5.51 hrs e. 9.27 hrs

____ 104. Compounds A and B react to form C and D in a reaction that is found to be second-order overall and second-order in B. The rate constant at 50°C is 2.48 liter per mole per minute. What is the half-life of B (in min) if 0.822 M B reacts with excess A?

A + B → C + D

a. 0.0139 b. 12.0 c. 1.39 d. 0.491 e. 5.88

____ 105. At 300 K the reaction below obeys the rate law rate = k[NOCl]2 where k = 2.8 × 10-5 M-1•s-1.

2NOCl → 2NO + Cl2

Suppose 1.0 mole of NOCl is introduced into a 2.0-liter container at 300 K. How much NOCl will remain after 30 minutes?a. 0.77 mol b. 0.84 mol c. 0.87 mol d. 0.63 mol e. 0.95 mol

____ 106. At 100 K the reaction below obeys the rate law rate = k[AB2]2 wherek = 5.7 M-1•s-1. 2AB2 → A2 + 2B2

What would the concentration of AB2 be after 60 minutes if the initial concentration was 1.45 mol/L?a. 4.9 × 10-5 M b. 2.0 × 10-5 M c. 1.2 × 10-2 M d. 2.4 × 10-5 M e. 1.9 × 10-4 M

Name: ________________________ ID: A

18

____ 107. At a certain temperature the reaction 2B → C + D obeys the rate-law expression rate = (1.14 × 10-3 M-1•s-1)[B]2. If 5.00 mol of B is initially present in a 1.00-L container at that temperature, how long would it take for 2.00 mol of B to be consumed at constant temperature?a. 224 s b. 87.5 s c. 46.0 s d. 73.0 s e. 58.5 s

____ 108. Compounds A and B react to form C and D in a reaction that is found to be second-order overall and second-order in B. The rate constant at 30°C is 0.622 liter per mole per minute. A + B → C + D

How many minutes does it take 4.0 × 10-2 M B (mixed with excess A) to be reduced to 3.3 × 10-2 M B?a. 1.4 min b. 3.6 min c. 5.0 min d. 6.4 min e. 8.5 min

____ 109. Which statement is incorrect?a. The reaction rate for a zero-order reaction is independent of concentrations.b. The specific rate constant for a second-order reaction is independent of

temperature.c. The half-life for a first-order reaction is independent of initial concentrations.d. The rate law expression relates rate and concentration.e. The integrated rate equation relates time and concentration.

____ 110. Which of the following statements concerning graphical methods for determining reaction order is false?a. For a first-order reaction the plot of ln [A] vs. time gives a straight line. b. For a first-order reaction the slope of the straight-line graph equals -ak. c. For a second-order reaction the plot of [A]2 vs. time gives a straight line. d. For a first-order reaction the intercept of the straight-line graph equals ln [A]0. e. For a zero-order reaction the plot of [A] vs. time gives a straight line.

____ 111. Which one of the following statements is false?a. In order for a reaction to occur, reactant molecules must collide with each other. b. A catalyst alters the rate of a reaction and is neither a product nor a reactant in the overall equation. c. According to collision theory a three-body collision is less likely than a two-body collision. d. In reactions that are second order in one reactant and first order in another, the slow step generally involves a three-body collision of these reactants. e. The transition state is a short-lived, high energy state, intermediate between reactants and products.

____ 112. Which of the following statements regarding collision and transition state theory is false?a. Reactants must collide to form products. b. All reactant collisions result in product formation. c. Activation energy is always positive. d. Reactant molecules must absorb energy to form the transition state. e. Reactant collisions must be oriented properly to form products.

____ 113. Which statement is false?a. If a reaction is thermodynamically spontaneous, it may occur rapidly. b. A fast reaction may be thermodynamically spontaneous. c. If a reaction is thermodynamically spontaneous, it may occur slowly. d. If a reaction is thermodynamically spontaneous, it must have a low activation energy. e. Rate of reaction is a kinetic quantity rather than a thermodynamic quantity.

Name: ________________________ ID: A

19

____ 114. A reaction has an activation energy of 40 kJ and an overall energy change of reaction of -100 kJ. In each of the following potential energy diagrams, the horizontal axis is the reaction coordinate and the vertical axis is potential energy in kJ. Which potential energy diagram best describes this reaction?

a. b. c. d.

e.

____ 115. Given the following potential energy diagram for the one-step reaction

X + Y → Z + R The reaction __________.

a. releases energy b. absorbs energy c. is impossible d. occurs without a net change in energy e. may either absorb or release energy

____ 116. Given the following potential energy diagram for the one-step reaction

X + Y → Z + R The arrow "d" represents the __________.

a. energy content of products b. activation energy for the forward reaction c. energy content of reactants d. activation energy for the reverse reaction e. the net change in energy for the reaction

Name: ________________________ ID: A

20

____ 117. Given the following potential energy diagram for the one-step reaction

X + Y → Z + R The arrow "a" represents the __________.

a. energy content of products b. activation energy for the forward reaction c. energy content of reactants d. activation energy for the reverse reaction e. the net change in energy for the reaction

____ 118. Given the following potential energy diagram for the one-step reaction

X + Y → Z + R The point "b" represents __________.

a. the energy of the mixture when half of the reactants have been converted to products b. the energy of the transition state c. the number of moles of transition state that must be formed d. the energy of the forward reaction e. the energy of the reverse reaction

____ 119. Given the following potential energy diagram for the one-step reactionX + Y → Z + R The arrow "c" represents the __________.

a. net energy of reaction for the forward reaction b. activation energy for the forward reaction c. net energy of reaction for the reverse reaction d. activation energy for the reverse reaction e. energy content for the reaction

Name: ________________________ ID: A

21

____ 120. Which of the following statements about reaction mechanisms is false?a. A reaction can have more than one possible mechanism. b. A reaction mechanism must be consistent with the experimentally observed rate law. c. The slowest step in the reaction mechanism is called the rate-determining step. d. Reaction mechanisms involve complex reaction steps. e. Reaction mechanisms are difficult to prove.

____ 121. A reaction mechanism will usually bea. the only possible explanation for the reaction. b. difficult to verify experimentally. c. proven experimentally to be the balanced chemical equation. d. obvious from a consideration of the balanced chemical equation. e. obvious from a consideration of the reaction rate data.

____ 122. Which of the following is a kinetics concept?a. free energy b. enthalpy c. spontaneity d. reaction mechanism e. entropy

____ 123. Consider the hypothetical reaction shown below.

A + 2B → AB2

Assume that the following proposed mechanism is consistent with the rate data.

B + B → B2 slowB2 + A → AB + B fastB + AB → AB2 fastA + 2B → AB2 overall

Which one of the following statements must be true? The reaction is __________.a. first order in A, second order in B, and third order overall b. second order in B and second order overall c. first order in A and first order overall d. second order in B, zero order in A, and third order overall e. second order in A and second order overall

____ 124. Consider the hypothetical reaction shown below.

2A + C2 → A2C + C

Assume that the following proposed mechanism is consistent with the rate data.

A + C2 → AC + C slowAC + A → A2C fast2A + C2 → A2C + C overall

Which one of the following statements must be true? The reaction is __________.a. first order in A, first order in B, and third order overall b. second order in C2 and second order overall c. first order in A and first order in C2 d. second order in C2, zero order in A, and third order overall e. second order in A and second order overall

Name: ________________________ ID: A

22

____ 125. Consider the following proposed mechanism. If this mechanism for the overall reaction were correct, and if k1 were much less than k2, then the observed rate law would be

2A k1→⎯⎯⎯ C + I

I + B k2→⎯⎯⎯ C + D

a. rate =k1[A] b. rate =k2[I][B] c. rate =k1[A]2 d. rate =k1[A]2 -k2[C][D] e. rate =k1k2[A]2[I][B]

____ 126. Suppose the reaction

2AB + C2 → A2C + B2C

occurs by the following mechanism.

Step 1 AB + C2 → AC2 + B slowStep 2 B + AB → AB2 fastStep 3 AC2 + AB2 → A2C2 +B2 fastStep 4 A2C2 + B2 → A2C + B2C fastOverall 2 AB + C2 → A2C + B2C

The rate law expression must be rate = __________.a. k[AB][C2] b. k[AB]2[C2] c. k[AB]2 d. k[AB] e. k[C2]

____ 127. Assume the following reaction

3H2 + CO → CH4 + H2O

occurs by the given reaction mechanism.

Step 1 H2 + CO → H2CO slowStep 2 H2 + H2CO → CH4 + O fastStep 3 H2 + O → H2O fastOverall 3H2 + CO → CH4 + H2O

The rate law expression must be rate = __________.a. k[H2]2[CO]2 b. k[H2]2[CO] c. k[H2][CO]2 d. k[H2][CO] e. k[H2]2[CO]3

Name: ________________________ ID: A

23

____ 128. The disproportionation (auto-oxidation-reduction) of the hypochlorite ion to chlorate and chloride ions occurs in aqueous solution. The rate expression is found to be rate = k[ClO-]2. Which one of the following (possible) mechanisms is consistent with this information?

3ClO- → ClO3- + 2Cl-

a. ClO- + ClO- → ClO2- + Cl- (slow)

ClO- + ClO2- → ClO3- + Cl- (fast)

b. ClO- → Cl + O- (slow)O- + ClO- → Cl- + O2- (fast)O2- + Cl → Cl- + O2 (fast)O2 + ClO- → ClO3- (fast)

c. 3ClO- → ClO3- + 2Cl- (one step)d. ClO- → Cl- + O (slow)

O + ClO- → O2 + Cl- (fast)ClO- + O2 → ClO3- (fast)

e. 3ClO- → ClO2- + Cl2O2- (slow)

Cl2O2- → Cl- + ClO- (fast)

ClO- + ClO2- → Cl- + ClO3- (fast)

____ 129. Consider the reaction below and its observed rate law expression. Which proposed mechanisms are consistent with the rate law expression?

2NO2 → 2NO + O2rate =k[NO2]2

I. NO2 + NO2 → N2O4 slowN2O4 → N2 + 2O2 fastN2 + O2 → 2NO fast2NO2 → 2NO + O2 overall

II. NO2 → N + O2 slowNO2 + N → N2O2 fastN2O2 → 2NO fast2NO2 → 2NO + O2 overall

III. NO2 → NO + O slowO + NO2 → NO + O2 fast2NO2 → 2NO + O2 overall

a. I b. II c. III d. I and III e. another combination

Name: ________________________ ID: A

24

____ 130. At 300 K the following reaction is found to obey the rate law rate =k[NOCl]2.

2NOCl → 2NO + Cl2

Consider the three postulated mechanisms given below. Then choose the response that lists all those that are possibly correct and no others.

I. NOCl → NO + Cl slowCl + NOCl → NOCl2 fastNOCl2 + NO → 2NO + Cl2 fast2NOCl → 2NO + Cl2

II. 2NOCl → NOCl2 + NO slowNOCl2 → NO + Cl2 fast2NOCl → 2NO + Cl2

III. NOCl → NO + Cl fastNOCl + 2Cl → NO + Cl2 slow2NOCl → 2NO + Cl2

a. I b. II c. III d. I and II e. II and III

____ 131. Which statement concerning a possible mechanism for a reaction is false?a. A possible mechanism must be consistent with the experimental data. b. Each elementary step is represented by a balanced equation. c. The elementary steps must add to give the equation for the overall reaction. d. The speed of the slow step limits the rate at which the overall reaction occurs. e. For all reactions the experimentally determined reaction orders of the reactants indicate the number of molecules of those reactants involved in the slow step of the mechanism.

____ 132. Which of the following statements concerning a reaction and its mechanism is false?a. For a reactant, more is consumed than is formed. b. For a product, more is formed than is consumed. c. A reaction intermediate is formed in early steps and completely consumed in later steps. d. For a multi-step mechanism, the slowest step has the highest activation energy. e. Reactions involving simultaneous trimolecular collisions are very common in gases.

____ 133. Reaction rates increase with increasing temperature because __________.a. the activation energy increases b. larger molecules collide more frequently c. the energy of the transition state is lowered d. the activation energy is decreased e. a greater fraction of molecules possess the activation energy when they collide

____ 134. Which response contains all the following statements that are true and no false statements?

I. Reactions with more negative values of ΔG0 are more spontaneous and proceed at higher rates than those with less negative values of ΔG0.

II. The activation energy, Ea, is usually about the same as ΔE for a reaction.III. The activation energy for a reaction does not change as temperature changes.IV. Reactions generally occur at faster rates at higher temperatures.

a. I and II b. III and IV c. I, II, and III d. II, III, and IV e. I, II, III, and IV

Name: ________________________ ID: A

25

____ 135. Suppose the activation energy of a certain reaction is 250 kJ/mol. If the rate constant at

T1 = 300 K is k1, and the rate constant at T2 = 320 K is k2, then k2/k1 = __________. (The universal gas constant = 8.314 J/mol•K.)

1nk 2

k 1

Ê

Ë

ÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃

=Ea

R1

T1− 1

T2

Ê

Ë

ÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃

a. 3 × 10-29 b. 0.067 c. 15.0 d. 525 e. 3 × 1028

____ 136. Suppose the activation energy of a certain reaction is 250 kJ/mol. If the rate constant at

T1 = 300 K is k1, and the rate constant at T2 = 320 K is k2, then k2/k1 = __________. (The universal gas constant = 8.314 J/mol•K.)a. 3 × 10-29 b. 0.067 c. 15.0 d. 525 e. 3 × 1028

____ 137. The specific rate constant, k, for a reaction is 2.64 × 10-2 s-1 at 25°C, and the activation energy is 74.0 kJ/mol. Calculate k at 50°C. (The universal gas constant = 8.314 J/mol•K.)

1nk 2

k 1

Ê

Ë

ÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃

=Ea

R1

T1− 1

T2

Ê

Ë

ÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃

a. 0.832 s-1 b. 71.9 s-1 c. 0.266 s-1 d. 1.08 s-1 e. 0.0265 s-1

____ 138. The specific rate constant, k, for a reaction is 0.44 s-1 at 298 K, and the activation energy is 245.kJ/mol. Calculate k at 398 K. (The universal gas constant = 8.314 J/mol•K.)

1nk 2

k 1

Ê

Ë

ÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃

=Ea

R1

T1− 1

T2

Ê

Ë

ÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃

a. 2.71 × 1010 s-1 b. 6.17 × 1010 s-1 c. 1.03 × 1010 s-1 d. 8.32 × 108 s-1 e. 4.51 × 109 s-1

____ 139. The specific rate constant, k, for a reaction is 2.64 × 10-2 s-1 at 25°C, and the activation energy is 74.0 kJ/mol. Calculate k at 50°C.a. 0.832 s-1 b. 71.9 s-1 c. 0.266 s-1 d. 1.08 s-1 e. 0.0265 s-1

____ 140. The rate constant, k, for a first-order reaction is 1.20 × 102 s-1 at 45°C and the activation energy is 98.2 kJ/mol. Calculate the rate constant for this reaction at 95°C.a. 1.87 × 104 s-1 b. 7.72 × 10-1 s-1 c. 6.06 × 10-2 s-1 d. 1.40 × 103 s-1 e. 2.02 × 105 s-1

____ 141. The rate constant, k, for a first-order reaction is 1.36 × 103 s-1 at 90.°C and the activation energy is 78.4 kJ/mol. Calculate the rate constant for this reaction at 50.°C.a. 60.4 s-1 b. 54.5 s-1 c. 23.8 s-1 d. 4.85 s-1 e. 1.78 × 103 s-1

Name: ________________________ ID: A

26

____ 142. Calculate the activation energy of a reaction if the rate constant is 0.75 s-1 at 25°C and 11.5 s-1 at 75°C. (The universal gas constant = 8.314 J/mol•K.)

1nk 2

k 1

Ê

Ë

ÁÁÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃˜̃

=Ea

R1

T1− 1

T2

Ê

Ë

ÁÁÁÁÁÁ

ˆ

¯

˜̃̃˜̃̃

a. 681 J/mol b. 20.4 kJ/mol c. 15.8 kJ/mol d. 47.1 kJ/mol e. 31.4 kJ/mol

____ 143. Calculate the activation energy of a reaction if the rate constant is 0.75 s-1 at 25°C and 11.5 s-1 at 75°C.a. 681 J/mol b. 20.4 kJ/mol c. 15.8 kJ/mol d. 47.1 kJ/mol e. 31.4 kJ/mol

____ 144. Calculate the activation energy of a reaction if its rate constant is 2.8 × 106 s-1 at 24°C and 1.5 × 107 s-1 at 48°C.a. 26 kJ/mol b. 80. kJ/mol c. 55 kJ/mol d. 67 J/mol e. 3.51 J/mol

____ 145. What would be the activation energy of a reaction if its rate constant at 35°C was double the value of its rate constant at 25°C?a. 63.8 kJ/mol b. 75.1 kJ/mol c. 8.12 kJ/mol d. 52.9 kJ/mol e. 68.3 J/mol

____ 146. A catalyst __________.a. is used up in a chemical reaction b. changes the value of ΔG0 of the reaction c. is always a solid d. does not influence the reaction in any way e. changes the activation energy of the reaction

____ 147. A catalysta. increases the amount of products present at equilibrium. b. increases the rate at which equilibrium is reached but decreases the equilibrium constant. c. increases the rate at which equilibrium is reached without changing the equilibrium constant. d. increases ΔH for the process. e. lowers ΔS for the process.

____ 148. Which of the following statements about catalysts are false?a. A catalyst lowers the activation energy. b. A catalyst can make a nonspontaneous reaction spontaneous. c. A catalyst speeds up both the forward and reverse reaction. d. A catalyst speeds up the rate of reaction. e. Catalyst are often transition metals and transition metal oxides.

____ 149. Which of the following is not an example of an important, useful reaction catalyzed by transition metals and/or their oxides?a. the Haber process for the production of ammonia b. the contact process for the production of sulfur trioxide in producing sulfuric acid c. the hydrogenation of unsaturated hydrocarbons d. the reaction of leaded fuels with the catalysts in catalytic converters e. the chlorination of benzene

____ 150. Consider the following catalyzed reaction.

2 NO (g) NiO, Pt→⎯⎯⎯⎯ N2 (g) + O2 (g)

Which response includes only true statements?

I. Pt and NiO are catalystsII. This is an example on homogeneous catalysisIII. This reaction would not be spontaneous without the catalysts

a. I, II b. I, II, III c. I d. II, III e. I, III

Name: ________________________ ID: A

27

____ 151. The catalytic converters installed in newer models of automobiles are designed to catalyze certain kinds of favorable reactions. Unfortunately, other unfavorable reactions also are catalyzed. Which one of those listed below, all of which are catalyzed in such mufflers, is an unfavorable reaction?a. 2CO(g) + O2(g) → 2CO2(g) b. 2C8H18(g) + 25O2(g) → 16CO2(g) + 18H2O(g) c. C(s) + O2(g) → CO2(g) d. 2SO2(g) + O2(g) → 2SO3(g) e. 2NO(g) → N2(g) + O2(g)

____ 152. Which statement concerning biological catalysts is false?a. Enzymes are proteins that act as catalysts for specific biochemical reactions. b. The reactants in enzyme-catalyzed reactions are called substrates. c. Each enzyme catalyzes many different reactions in a living system. d. Enzyme-catalyzed reactions are important examples of zero-order reactions. e. Discovery or synthesis of catalysts that mimic the efficiency of naturally occurring enzymes would saved on the costs of using high temperature and high pressure in commercial processes.

____ 153. The reaction, A + 2B → B2 + A, proceeds by the following mechanism: (A is a catalyst.)

A + B → AB (slow)AB + B → B2 + A (fast)

What is the rate law expression for this reaction?a. Rate =k[A] b. Rate =k[B] c. Rate =k[A][B] d. Rate =k[A][B]2 e. Rate =k[A]2[B]

CompletionComplete each statement.

154. The reaction mechanism for a catalyzed decomposition of hydrogen peroxide is shown below.

H2O2(aq) + I-(aq) → H2O(™) + IO-(aq)IO-(aq) + H2O2(aq) → H2O(™) + O2(g) + I-(aq)

Because the iodide ion is in the same phase as the reactants, it is referred to as a ________ catalyst.

155. The ________ of an elementary step is defined as the number of reactant molecules that come together in the reaction.

156. The pre-exponential, A, in the Arrhenius equation is called the ________ factor.

157. For a ________-order reaction, the half-life is independent of the initial reactant concentration.

158. Elementary steps in a reaction mechanism often include reaction ________. These (usually) short-lived species do not appear in the overall chemical reaction.

Essay

159. How is the enthalpy change in a chemical reaction affected by the addition of a catalyst?

160. The decay of radioactive elements is a first-order process. The half-life of carbon-14 is 5730 years. How many years will it take for 1.00 kg of carbon -14 to decay to 1.00 g?

161. What is implied if a reactant has a negative reaction order in the rate law expression? Are fractional orders possible?

Name: ________________________ ID: A

28

162. Describe the concept of a transition state. Why can't we collect and study transition state species? What observations about the transition state lead us to conclude that it is unstable?

163. Propose a 3-step mechanism for the following reaction, which shows 1st order dependence for both H2 and CO. 3H2 + CO → CH4 + H2O

164. Monoatomic chlorine is a catalyst in the decomposition of ozone, O3. Explain how a single chlorine atom is capable of decomposing thousands of O3 molecules.

ID: A

1

Kinetics Practice questionsAnswer Section

MULTIPLE CHOICE

1. D 2. C 3. E 4. B 5. A 6. C 7. A 8. C 9. B 10. C 11. E 12. A 13. E 14. D 15. B 16. A 17. D 18. A 19. B 20. B 21. C 22. C 23. E 24. B 25. A 26. B 27. E 28. E 29. C 30. C 31. B 32. A 33. D 34. C 35. D 36. B 37. C 38. D 39. A 40. C

ID: A

2

41. D 42. A 43. B 44. A 45. E 46. D 47. C 48. A 49. E 50. B 51. B 52. D 53. D 54. E 55. C 56. E 57. C 58. D 59. C 60. D 61. A 62. B 63. E 64. A 65. A 66. E 67. E 68. D 69. A 70. A 71. B 72. C 73. D 74. C 75. B 76. D 77. E 78. E 79. D 80. C 81. C 82. E 83. B 84. C 85. D 86. A

ID: A

3

87. A 88. E 89. A 90. A 91. C 92. A 93. B 94. C 95. C 96. C 97. A 98. D 99. A 100. B 101. C 102. B 103. C 104. D 105. E 106. D 107. E 108. E 109. B 110. C 111. D 112. B 113. D 114. A 115. A 116. E 117. B 118. B 119. D 120. D 121. B 122. D 123. B 124. C 125. C 126. A 127. D 128. A 129. A 130. B 131. E 132. E

ID: A

4

133. E 134. B 135. D 136. D 137. C 138. A 139. C 140. A 141. B 142. D 143. D 144. C 145. D 146. E 147. C 148. B 149. D 150. C 151. D 152. C 153. C

COMPLETION

154. homogeneous 155. molecularity 156. frequency 157. first 158. intermediates

ESSAY

159. The enthalpy change is unaffected by the addition of a catalyst. The catalyst reduces the activation barrier, thereby increasing the reaction rate.

160. 5.71 × 104 years 161. Answer not provided. 162. Answer not provided. 163. Answer not provided. 164. Answer not provided.