Deck 15: Chemical Kinetics

Question 1

For the reaction 2A + 3B $\rightarrow$ 4C + 5D, the rate of the reaction in terms of $\Delta$ B would be written as __________

A) - $\Delta$ B/ $\Delta$ t
B) + $\Delta$ B/ $\Delta$ t
C) -1/3 $\Delta$ B/ $\Delta$ t
D) +1/3 $\Delta$ B/ $\Delta$ t
E) -3 $\Delta$ B/ $\Delta$ t

Answer 1

-1/3 $\Delta$ B/ $\Delta$ t

Question 2

For the reaction 2A + 3B $\rightarrow$ 4C + 5D, the rate of the reaction in terms of $\Delta$ C would be written as __________

A) + $\Delta$ C/ $\Delta$ t
B) +4 $\Delta$ C/ $\Delta$ t
C) +1/4 $\Delta$ C/ $\Delta$ t
D) -4 $\Delta$ C/ $\Delta$ t
E) -1/4 $\Delta$ C/ $\Delta$ t

Answer 2

+1/4 $\Delta$ C/ $\Delta$ t

Question 3

Indicate which of the following compounds is not a component of photochemical smog.

A) O₃
B) H₂O
C) NO₂
D) NO
E) Organic molecules

Answer 3

H₂O

Question 4

At what time of day are ozone concentrations highest during a photochemical smog event?

A) in the morning before rush hour
B) in the morning just after rush hour
C) midmorning
D) noon
E) midafternoon

Question 5

For the reaction 2A + 3B $\rightarrow$ 4C + 5D, the rate of the reaction in terms of $\Delta$ A would be written as __________

A) - $\Delta$ A/ $\Delta$ t.
B) -1/2 $\Delta$ A/ $\Delta$ t.
C) + $\Delta$ A/ $\Delta$ t.
D) +1/2 $\Delta$ A/ $\Delta$ t.
E) -2 $\Delta$ A/ $\Delta$ t.

Question 6

The device in automobiles that has decreased NO and partially oxidized hydrocarbons from exhaust gases is termed a(n) __________

A) catalytic intermediate.
B) photochemical inhibitor.
C) catalytic linker.
D) nitrogen monoxide reducer.
E) catalytic converter.

Question 7

The order in which ozone, nitrogen monoxide, and nitrogen dioxide build up in the atmosphere over the course of the day is in the order __________ then __________ then __________

A) NO; NO₂; O₃.
B) NO; O₃; NO₂.
C) NO₂; NO; O₃.
D) NO₂; O₃; NO.
E) O₃; NO; NO₂.

Question 8

In the combustion of methane, CH₄(g) + 2 O₂(g) $\rightarrow$ CO₂(g) + 2 H₂O (g), which reactant has the greatest rate of disappearance?

A) CH₄
B) O₂
C) CO₂
D) H₂O
E) CH₄ and O₂ have the same rate of disappearance.

Question 9

Assuming that each of the following graphs has the same concentration and time axes, which has the greatest initial rate of disappearance of reactant?

A)
B)
C)
D)

Question 10

Indicate which of the following compounds is a component of photochemical smog.

A) H₂O
B) CO₂
C) N₂O
D) O₃
E) CO

Question 11

Which of the following statements is true about the instantaneous rate for the chemical reaction A $\rightarrow$ B as the reaction progresses?

A) - $\Delta$ A/ $\Delta$ t increases while $\Delta$ B/ $\Delta$ t decreases
B) - $\Delta$ A/ $\Delta$ t decreases while $\Delta$ B/ $\Delta$ t increases
C) both - $\Delta$ A/ $\Delta$ t and $\Delta$ B/ $\Delta$ t decrease
D) both - $\Delta$ A/ $\Delta$ t and $\Delta$ B/ $\Delta$ t increase
E) The answer will vary depending on the reaction mechanism.

Question 12

The following graph shows the kinetics curves for the reaction of oxygen with hydrogen to form water: O₂(g) + 2H₂(g) $\rightarrow$ 2H₂O(g). Which curve is hydrogen?

A) the dashed curve
B) the gray curve
C) the black curve
D) either the gray or the black curve
E) Any of these curves could be hydrogen.

Question 13

Large cities often issue ozone advisories. At what time of year would an advisory be likely to occur most often?

A) winter
B) spring
C) summer
D) fall
E) No season should have more advisories than another.

Question 14

Smog created by the interaction of sunlight with nitrogen oxides and volatile organic compounds is termed __________ smog.

A) photolytic
B) photochemical
C) photophysical
D) acid
E) sulfurous

Question 15

Which of the following is not important as a contributing factor to photochemical smog?

A) stagnant air
B) sunlight
C) lots of traffic
D) irrigation
E) cars without catalytic converters

Question 16

NO₂ contributes to the "brown haze" associated with photochemical smog events. At what time of day is NO₂ concentration highest?

A) in the morning before rush hour
B) in the morning just after rush hour
C) midmorning
D) noon
E) midafternoon

Question 17

The greatest NO concentration is observed __________

A) in the morning before rush hour.
B) in the morning just after rush hour.
C) in midmorning.
D) at noon.
E) in midafternoon.

Question 18

For the reaction 2A + 3B $\rightarrow$ 4C + 5D, the rate of the reaction in terms of $\Delta$ D would be written as __________

A) + $\Delta$ D/ $\Delta$ t
B) +5 $\Delta$ D/ $\Delta$ t
C) +1/5 $\Delta$ D/ $\Delta$ t
D) -5 $\Delta$ D/ $\Delta$ t
E) -1/5 $\Delta$ D/ $\Delta$ t

Question 19

When one chemical is a precursor of another chemical in a series of reactions, the concentrations of the two species are said to be __________

A) catalytic.
B) volatile.
C) coalescent.
D) linked.
E) intermediate.

Question 20

Which of the following is not a possible graph of concentration versus time for a reactant?

A)
B)
C)
D)

Question 21

The rate of disappearance of HI in the reaction 2HI(g) $\rightarrow$ I₂(g) + H₂(g) is shown in the following figure. What is the instantaneous rate of this reaction at t = 5 s?

A) 0.2 M/s
B) 0.01 M/s
C) 0.02 M/s
D) 0.100 M/s
E) 0.04 M/s

Question 22

HI dissociates to form I₂ and H₂: 2HI(g) $\rightarrow$ H₂(g) + I₂(g)
If the concentration of HI changes at a rate of -0.45 M/s, what is the rate of appearance of I₂(g)?

A) 0.90 M/s
B) 0.45 M/s
C) 0.23 M/s
D) 1.00 M/s
E) 0.13 M/s

Question 23

If the rate of the reaction: 2O₃(g) $\rightarrow$ 3O₂(g)
Is 0.250 M/s over the first 5.50 s, how much oxygen will form during this time?

A) 1.38 M
B) 4.13 M
C) 0.69 M
D) 0.25 M
E) 0.46 M

Question 24

Which of the following does the initial rate of a chemical reaction depend on?
(I)Concentration of reactants
(II)Concentration of products
(III)Temperature

A) I
B) III
C) II
D) Both I and III
E) I, II, and III

Question 25

The difference between an average rate and an instantaneous rate is __________

A) the average rate is taken over a larger time period.
B) the instantaneous rate is taken from the slope of the curve at a specific time.
C) they are not different if the time interval chosen is small enough.
D) All the above are correct.

Question 26

For the rate law Rate = k[A][B]^3/2, the partial order with respect to A is __________, the partial order with respect to B is __________, and the total order is __________.

A) 0; ;
B) 1; ; 1
C) 1; ;
D) 1; ;
E) The orders cannot be determined without a chemical reaction.

Question 27

If the rate of appearance of O₂ in the reaction: 2O₃(g) $\rightarrow$ 3O₂(g)
Is 0.250 M/s over the first 5.50 s, how much oxygen will form during this time?

A) 1.38 M
B) 4.13 M
C) 0.69 M
D) 0.25 M
E) 0.46 M

Question 28

For the rate law Rate = k[A][B]^1/2, the partial order with respect to A is __________, the partial order with respect to B is __________, and the total order is __________.

A) 0; ;
B) 1; ; 1
C) 1; ;
D) 1; ;
E) The orders cannot be determined without a chemical reaction.

Question 29

The reaction A + 2B $\rightarrow$ C
Is first order in B and A. The overall order of the reaction is __________

A) first.
B) second.
C) third.
D) zero.
E) fourth.

Question 30

For the rate law Rate = k[A]^3/2[B], the partial order with respect to A is __________, the partial order with respect to B is __________, and the total order is __________.

A) ; 0;
B) ; 1; 1
C) ; 1;
D) ; 1;
E) The orders cannot be determined without a chemical reaction.

Question 31

For the rate law Rate = k[A]^1/2[B], the partial order with respect to A is __________, the partial order with respect to B is __________, and the total order is __________.

A) ; 0;
B) ; 1; 1
C) ; 1;
D) ; 1;
E) The orders cannot be determined without a chemical reaction.

Question 32

A scientist conducts an experiment to determine the rate of the following reaction: N₂(g) + O₂(g) $\rightarrow$ 2NO(g)
If the initial concentration of N₂ was 0.500 M and the concentration of N₂ was 0.450 M after 0.100 s, what is the rate of the reaction?

A) 0.500 M/s
B) 1.00 M/s
C) 5.00 M/s
D) 10.0 M/s
E) 0.250 M/s

Question 33

If the rate of formation of ammonia is 0.345 M/s, what is the rate of disappearance of N₂?

A) 0.173 M/s
B) 0.345 M/s
C) 0.690 M/s
D) 245 M/s
E) 0.518 M/s

Question 34

A scientist conducts an experiment to determine the rate of NO formation in the reaction: N₂(g) + O₂(g) $\rightarrow$ 2NO(g)
If the initial concentration of N₂ was 0.500 M and the concentration of N₂ was 0.450 M after 0.100 s, what is the rate of NO formation?

A) 0.500 M/s
B) 1.00 M/s
C) 5.00 M/s
D) 10.0 M/s
E) 0.250 M/s

Question 35

If the rate of formation of ammonia is 0.345 M/s, what is the rate of disappearance of N₂? N₂(g) + 3H₂(g) $\rightarrow$ 2NH₃(g)

A) 0.173 M/s
B) 0.345 M/s
C) 0.690 M/s
D) 245 M/s
E) 0.518 M/s

Question 36

In a rate law, the partial orders are determined by __________

A) the reactant concentrations.
B) the stoichiometric coefficients.
C) the product concentrations.
D) experiment.
E) the difference between the forward and reverse rates.

Question 37

If the reaction 3A + B + C $\rightarrow$ 2D + E is first order overall, which of these could be the units of its rate constant, k?

A) 1/s
B) M/s
C) 1/Ms
D) 1/Ms²
E) Ms

Question 38

Which of these could be the units of the rate constant for a first-order reaction?

A) M/s
B) 1/Ms
C) 1/Ms²
D) 1/s
E) Ms

Question 39

Ammonia gas (NH₃) is produced from hydrogen and nitrogen gas according to the following reaction: 3H₂(g) + N₂(g) $\rightarrow$ 2NH₃(g)
If the rate of production of ammonia is R(NH₃), what is the rate of loss of hydrogen and nitrogen gas, respectively?

A) -R(H₂) = 2/3 R(NH₃); -R(N₂) = 1/2 R(NH₃)
B) -R(H₂) = 3/2 R(NH₃); -R(N₂) = 2 R(NH₃)
C) -R(H₂) = 3/2 R(NH₃); -R(N₂) = 1/2 R(NH₃)
D) -R(H₂) = 2/3 R(NH₃); -R(N₂) = 2 R(NH₃)
E) -R(H₂) = R(NH₃); -R(N₂) = R(NH₃)

Question 40

A scientist conducts an experiment to determine the rate of the following reaction: N₂(g) + O₂(g) $\rightarrow$ 2NO(g)
If the initial concentration of NO was 0.00 M and the concentration of NO was 0.050 M after 0.100 s, what is the rate of the reaction?

A) 0.500 M/s
B) 1.00 M/s
C) 5.00 M/s
D) 10.0 M/s
E) 0.250 M/s

Question 41

A second-order reaction (2A $\rightarrow$ B) with a rate constant of 0.350 M^-1s^-1 is found to have a half-life of 3.45 s. What was the initial concentration of the reactant, [A]₀?

A) 0.828 M
B) 0.201 M
C) 1.00 M
D) 1.21 M
E) 0.350 M

Question 42

The rate of a reaction is found to double when the concentration of one reactant is quadrupled. The order of the reaction with respect to this reactant is __________

A) first.
B) second.
C) one-quarter.
D) one-half.
E) third.

Question 43

The first-order reaction A $\rightarrow$ B, has k = 5.67 s^-1. If [A]₀ = 0.500 M, how long will it take [A] = 0.124 M?

A) 0.122 s
B) 0.100 s
C) 8.18 s
D) 0.244 s
E) 0.488 s

Question 44

Indicate which of the following plots would be obtained for a second-order reaction.

A)
B)
C)
D)

Question 45

The second-order reaction A + B $\rightarrow$ C will obey pseudo first-order kinetics when __________

A) the concentrations of A and B are both small.
B) the concentration of one of the reactants does not change.
C) the concentration of C is large.
D) the concentrations of A and B are both large.
E) a catalyst changes the mechanism to a first-order reaction.

Question 46

Which of the following plots indicates that the reaction is zero order?

A)
B)
C)
D)

Question 47

Indicate which of the following plots would be obtained for a first-order reaction.

A)
B)
C)
D)

Question 48

The energy needed to form an activated complex is called __________

A) collision energy.
B) kinetic energy.
C) activation energy.
D) potential energy.
E) thermodynamic energy.

Question 49

Which of these could be the units for the rate constant in a second-order reaction?

A) M^-1 s
B) M s^-1
C) M^-1 s^-1
D) M^-2 s^-1
E) Ms

Question 50

The half-life (t_1/2) of a first-order reaction is 0.100 s. What is the rate constant?

A) 6.93 s^-1
B) 0.693 s^-1
C) 0.0693 s^-1
D) 0.144 s^-1
E) 3.01 s^-1

Question 51

Which point as labeled by an asterisk (*) on the following energy profile is the transition state?

A)
B)
C)
D)

Question 52

Which of the following plots would indicate that a reaction was first order?

A)
B)
C)
D)

Question 53

The energy profiles for four different reactions are shown. Which reaction requires the most energetic collisions to reach the transition state?

A) a
B) b
C) c
D) d

Question 54

The reaction CHCl₃(g) + Cl₂(g) $\rightarrow$ CCl₄(g) + HCl(g) has the following rate law: Rate = k[CHCl₃][Cl₂]. If the concentration of CHCl₃ is increased by a factor of five while the concentration of Cl₂ is kept the same, the rate will __________

A) double.
B) triple.
C) stay the same.
D) increase by a factor of five.
E) decrease by a factor of one-fifth.

Question 55

The reaction 2NO(g) + O₂(g) $\rightarrow$ 2NO₂(g) has the following rate law: Rate = k[O₂][NO]². If the concentration of NO is reduced by a factor of two, the rate will __________

A) double.
B) quadruple.
C) be reduced by one-quarter.
D) be reduced by one-half.
E) remain the same.

Question 56

Collision theory assumes that the rate of a reaction depends on __________

A) the energy of collisions.
B) the orientation of colliding molecules.
C) the energy of collisions and the orientation of colliding molecules.
D) the change in energy between the products and the reactants.
E) the change in free energy between the reactants and products.

Question 57

Which of the following plots indicates the reaction is second order?

A)
B)
C)
D)

Question 58

The second-order reaction A $\rightarrow$ B is found to have a rate constant of 0.978 M^-1s^-1. What is the half-life of this reaction when [A]₀ = 0.0300 M?

A) 0.0293 s
B) 0.710 s
C) 34.1 s
D) 60.1 s
E) 24.3 s

Question 59

The initial rate data for the reaction 2N₂O₅(g) $\rightarrow$ 4NO₂(g) + O₂(g) is shown in the following table. Determine the value of the rate constant for this reaction. Experiment
[N₂O₅](M)
Rate (M/s)
1
2.56*10³
450
2
1.28 *10²
22.5

A) 4.09 s^-1
B) 0.176 s^-1
C) 0.0569 s^-1
D) 0.225 s^-1
E) 80.1 s^-1

Question 60

A reaction is first order in A. If the rate constant of the reaction is 3.45 *10^-3 s^-1, what is the half-life (t_1/2) of the reaction?

A) 4.98 *10^-3 s
B) 200 s
C) 3.45 *10^-3 s
D) 100 s
E) 1.73 *10^-3 s

Question 61

The linear form of the Arrhenius equation is very useful, as it allows us to calculate the __________ from the slope and the __________ from the intercept.

A) frequency factor, activation energy
B) initial concentration, activation energy
C) activation energy, frequency factor
D) activation energy, Boltzmann constant
E) transition state, steric factor

Question 62

Given the following data for the reaction A $\rightarrow$ B, determine the activation energy, E_a, of the reaction. k (M/s)
T (K)
0)681
500
0)715
1000

A) 48.7 J/mol
B) 6.90 J/mol
C) 405 J/mol
D) 9.95 kJ/mol
E) 2.05 *10^-2 kJ/mol

Question 63

The linear form of the Arrhenius equation is very useful, as a plot of ____________ allows us to calculate the activation energy and the frequency factor.

A) the rate constant vs. temperature
B) the logarithm of the rate constant vs. the temperature
C) the rate constant vs. the inverse temperature
D) the logarithm of the rate constant vs. the inverse temperature
E) the inverse rate constant vs. the logarithm of the temperature

Question 64

The following figure shows Arrhenius plots for four different reactions. Which reaction has the lowest activation energy?

A) dashed
B) dotted
C) dash-dot
D) solid

Question 65

The energy profiles for four different reactions are shown. Which reaction requires the least energetic collisions to reach the transition state?

A) a
B) b
C) c
D) d

Question 66

The following figure shows Arrhenius plots for four different reactions. Which reaction has the greatest activation energy?

A) dashed
B) dotted
C) dash-dot
D) solid

Question 67

The following figure shows Arrhenius plots for four different reactions. Which reaction has the largest frequency factor?

A) dashed
B) dotted
C) dash-dot
D) solid

Question 68

The linear form of the Arrhenius equation is very useful as it allows us to calculate the activation energy from the __________ and the frequency factor from the __________.

A) slope, intercept
B) half-life, rate constant
C) intercept, slope
D) rate constant, slope
E) change in ln k, change in $\Delta$ (1/T)

Question 69

Given the following data for the reaction A $\rightarrow$ B, determine the frequency factor, A, of the reaction. k (M/s)
T (K)
0)730
250
0)739
450

A) +0.75
B) +0.719
C) +2.05
D) +0.287
E) -0.287

Question 70

The following figure shows Arrhenius plots for four different reactions. Which reaction has the greatest temperature dependence?

A) dashed
B) dotted
C) dash-dot
D) solid

Question 71

The linear form of __________ is very useful as it allows us to calculate the activation energy and the frequency factor.

A) the Boltzmann equation
B) the Arrhenius equation
C) Planck's equation
D) the rate law
E) the integrated rate law

Question 72

Given the following data for the reaction A $\rightarrow$ B, determine the activation energy, E_a, of the reaction. k (M/s)
T (K)
2)04 * 10^-4
250
6)78* 10^-3
400

A) 2.34 kJ/mol
B) 19.4 kJ/mol
C) 38.2 kJ/mol
D) 2.02 kJ/mol
E) 18.6 kJ/mol

Question 73

The following energy profiles for four different reactions are shown. Which reaction is the most exothermic?

A) a
B) b
C) c
D) d

Question 74

Given the following data for the reaction A $\rightarrow$ B, determine the activation energy, E_a, of the reaction. k (M/s)
T (K)
0)730
250
0)739
450

A) 54.4 J/mol
B) 6.89 J/mol
C) 39.9 J/mol
D) 57.3 J/mol
E) 374 J/mol

Question 75

The energy profiles for four different reactions are shown. Which of the reactions will have the smallest rate constant?

A)
B)
C)
D)

Question 76

The energy profiles for four different reactions are shown. Which of the reactions will have the largest rate constant?

A) a
B) b
C) c
D) d

Question 77

The following figure shows Arrhenius plots for four different reactions. Which reaction has the lowest frequency factor?

A) dashed
B) dotted
C) dash-dot
D) solid

Question 78

The following figure shows Arrhenius plots for four different reactions. Which reaction has the least temperature dependence?

A) dashed
B) dotted
C) dash-dot
D) solid

Question 79

Given the following data for the reaction A $\rightarrow$ B, determine the frequency factor, A, of the reaction. k (M/s)
T (K)
2)04 * 10^-4
250
6)78 *10^-3
400

A) 2.3
B) 5.3
C) 0.99
D) 0.63
E) 0.85

Question 80

The following energy profiles for four different reactions are shown. Which reaction is the most endothermic?

A) a
B) b
C) c
D) d