Deck 13: Chemical Kinetics

Question 1

For a reaction that follows the general rate law,Rate = k[A][B]²,what will happen to the rate of reaction if the concentration of A is increased by a factor of 3.00? The rate will

A)decrease by a factor of 1/9.00.
B)decrease by a factor of 1/3.00.
C)increase by a factor of 3.00.
D)increase by a factor of 9.00.

Answer 1

increase by a factor of 3.00.

Question 2

The decomposition of dinitrogen pentoxide is described by the chemical equation 2 N₂O₅(g)→ 4 NO₂(g)+ O₂(g)
If the rate of disappearance of N₂O₅ is equal to 1.40 mol/min at a particular moment,what is the rate of appearance of NO₂ at that moment?

A)0.700 mol/min
B)1.40 mol/min
C)2.80 mol/min
D)5.60 mol/min

Answer 2

2.80 mol/min

Question 3

What is the overall reaction order for the reaction that has the rate law: Rate = k[H₂][NO]²?

A)zero order
B)first order
C)second order
D)third order

Answer 3

third order

Question 4

Chlorine reacts with chloroform according to the reaction given below: Cl₂ + CHCl₃ → CCl₄ + HCl
When the initial concentration of Cl₂ is doubled the reaction rate increases by a factor of 1.41.What is the order of the reaction with respect to Cl₂?

A)-1/2
B)-1
C)1/2
D)2

Question 5

The following set of data was obtained by the method of initial rates for the reaction: 2 HgCl₂(aq)+ C₂O₄^2-(aq)→ 2 Cl^-(aq)+ 2 CO₂(g)+ Hg₂Cl₂(s)
What is the value of the rate constant,k?

A)1.4 × 10^-8 1/M²∙s
B)1.3 × 10^-7 1/M²∙s
C)1.4 × 10^-5 1/M²∙s
D)1.3 × 10^-4 1/M²∙s

Question 6

A concentration-time study of the gas phase reaction 2 A₃ → 3 A₂ produced the data in the table below. Time (s)[A₃] (M)[A₂] (M)
0 4.00 × 10^-4 0
10 2.00 × 10^-4 3.00 × 10^-4
20 1.00 × 10^-4 4.50 × 10^-4
30 5.00 × 10^-5 ?
What is the concentration of A₂ after 30 seconds?

A)5.00 × 10^-4 M
B)5.25 × 10^-4 M
C)5.50 × 10^-4 M
D)6.00 × 10^-4 M

Question 7

A concentration-time study of the gas phase reaction 2 A₃ → 3 A₂ produced the data in the table below. Time (s)[A₃] (M)[A₂] (M)
0 4.00 × 10^-4 0
10 2.00 × 10^-4 3.00 × 10^-4
20 1.00 × 10^-4 4.50 × 10^-4
30 5.00 × 10^-5 ?
What is the average rate of decomposition of A₃ in the time interval 20-30 seconds?

A)4.00 × 10^-4 M/s
B)3.50 × 10^-5 M/s
C)5.00 × 10^-6 M/s
D)4.00 × 10^-6 M/s

Question 8

Methanol can be produced by the following reaction: CO(g)+ 2 H₂(g)→ CH₃OH(g).
How is the rate of disappearance of hydrogen gas related to the rate of appearance of methanol?
- = ?

A)+
B)+
C)+2
D)none of these

Question 9

Iodide and hypochlorite ion react in aqueous solution according to the reaction below: I^- + OCl^- → OI^- + Cl^-
If the concentration of OH^- in the solution is doubled,the rate of the reaction is halved.What is the order of the reaction with respect to OH^-?

A)-2
B)-1
C)+1
D)+2

Question 10

Hydrogen peroxide decomposes to water and oxygen according to the reaction below: 2 H₂O₂(aq)→ 2 H₂O(l)+ O₂(g)
In the presence of large excesses of I^- ion,the following set of data is obtained.What is the average rate of disappearance of H₂O₂(aq)in M/s in the first 45.0 seconds of the reaction if 1.00 L of H₂O₂ reacts at 25°C and 1.00 atm pressure?

A)9.09 × 10^-7 M/s
B)3.63 × 10^-6 M/s
C)4.33 × 10^-5 M/s
D)1.64 × 10^-4 M/s

Question 11

Using the method of initial rates for the reaction A → B,if the initial concentration of A is doubled and the rate of reaction quadruples,what is the order of reaction with respect to A?

A)zeroth
B)first
C)second
D)fourth

Question 12

The decomposition of dinitrogen pentoxide is described by the chemical equation 2 N₂O₅(g)→ 4 NO₂(g)+ O₂(g)
If the rate of appearance of NO₂ is equal to 0.560 mol/min at a particular moment,what is the rate of appearance of O₂ at that moment?

A)0.140 mol/min
B)0.280 mol/min
C)1.12 mol/min
D)2.24 mol/min

Question 13

For a reaction that follows the general rate law,Rate = k[A][B]²,what will happen to the rate of reaction if the concentration of B is increased by a factor of 2.00? The rate will

A)decrease by a factor of 1/4.00.
B)decrease by a factor of 1/2.00.
C)increase by a factor of 2.00.
D)increase by a factor of 4.00.

Question 14

The reaction that occurs in a Breathalyzer,a device used to determine the alcohol level in a person's bloodstream,is given below.If the rate of appearance of Cr₂(SO₄)₃ is 1.24 mol/min at a particular moment,what is the rate of disappearance of C₂H₆O at that moment? 2 K₂Cr₂O₇ + 8 H₂SO₄ + 3 C₂H₆O → 2 Cr₂(SO₄)₃ + 2 K₂SO₄ + 11 H₂O

A)0.413 mol/min
B)0.826 mol/min
C)1.86 mol/min
D)3.72 mol/min

Question 15

The decomposition of dinitrogen pentoxide is described by the chemical equation 2 N₂O₅(g)→ 4 NO₂(g)+ O₂(g)
If the rate of appearance of O₂ is equal to 2.40 mol/min at a particular moment,what is the rate of disappearance of N₂O₅ at that moment?

A)0.600 mol/min
B)1.20 mol/min
C)4.80 mol/min
D)9.60 mol/min

Question 16

A concentration-time study of the gas phase reaction 2 A₃ → 3 A₂ produced the data in the table below. Time (s)[A₃] (M)[A₂] (M)
0 4.00 × 10^-4 0
10 2.00 × 10^-4 3.00 × 10^-4
20 1.00 × 10^-4 4.50 × 10^-4
30 5.00 × 10^-5 ?
What is the average rate of formation of A₂ in the time interval 20-30 seconds?

A)6.00 × 10^-4 M/s
B)5.25 × 10^-5 M/s
C)7.50 × 10^-6 M/s
D)6.00 × 10^-6 M/s

Question 17

The following set of data was obtained by the method of initial rates for the reaction: 2 HgCl₂(aq)+ C₂O₄^2-(aq)→ 2 Cl^-(aq)+ 2 CO₂(g)+ Hg₂Cl₂(s)
What is the rate law for the reaction?

A)Rate = k[HgCl₂][C₂O₄^2-]^-2
B)Rate = k[HgCl₂][C₂O₄^2-]^-1
C)Rate = k[HgCl₂]²[C₂O₄^2-]
D)Rate = k[HgCl₂][C₂O₄^2-]²

Question 18

The hydrolysis of tert-butyl chloride is given in the reaction below: (CH₃)₃CCl(aq)+ H₂O(l)→ (CH₃)₃COH(aq)+ H⁺(aq)+ Cl^-(aq)
If the rate law is: Rate = k[(CH₃)₃CCl],what is the order of the reaction with respect to water?

A)zero
B)first
C)second
D)third

Question 19

Molecular hydrogen can be made from methane gas by the reaction below.How is the rate of disappearance of CH₄ related to the rate of appearance of H₂? - = ?
CH₄ (g)+ H₂O (l)→ CO (g)+ 3H₂ (g)

A)+
B)+
C)+ 3
D)none of these

Question 20

The decomposition of ammonia to nitrogen and hydrogen on a tungsten filament at 800°C is independent of the concentration of ammonia at high pressures of ammonia.What is the order of the reaction with respect to ammonia?

A)zero
B)first
C)second
D)third

Question 21

The isomerization reaction,CH₃NC → CH₃CN,is first order and the rate constant is equal to 0.46 s^-1 at 600 K.What is the concentration of CH₃NC after 0.20 minutes if the initial concentration is 0.10 M?

A)4.0 × 10^-4 M
B)9.1 × 10^-4 M
C)4.0 × 10^-2 M
D)9.1 × 10^-2 M

Question 22

The first-order reaction,SO₂Cl₂ → SO₂ + Cl₂,has a half-life of 8.75 hours at 593 K.How long will it take for the concentration of SO₂Cl₂ to fall to 12.5% of its initial value?

A)0.165 hr
B)3.22 hr
C)6.06 hr
D)26.2 hr

Question 23

The decomposition of cyclopropane,was observed at 500°C and its concentration was monitored as a function of time.The data set is given below.What is the order of the reaction with respect to cyclopropane?

A)zero
B)first
C)second
D)third

Question 24

The data below were collected for the following reaction: 2 NO₂ (g)+ F₂ (g)2 NO₂F (g) What is the expression for the rate law of the reaction?

A)Rate = k[NO₂][F₂]
B)Rate = k[NO₂][F₂]²
C)Rate = k[NO₂]²[F₂]
D)Rate = k[NO₂]

Question 25

The half life of the reaction shown below is found not to depend on the concentration of H₂O₂(aq). 2 H₂O₂(aq)→ 2 H₂O(l)+ O₂(g)
What is the order of this reaction?

A)zeroth
B)first
C)second
D)third

Question 26

The rate constant,k,for a first-order reaction is equal to 4.2 × 10^-4 s^-1.What is the half-life for the reaction?

A)2.9 × 10^-4 s
B)1.2 × 10³ s
C)1.7 × 10³ s
D)2.4 × 10³ s

Question 27

The first-order decomposition of hydrogen peroxide occurs according to the equation 2 H₂O₂(aq)→ 2 H₂O(l)+ O₂(g)
Using data from a concentration-time study of this reaction,which plot will produce a straight line?

A)[H₂O₂] versus time
B)[H₂O₂]² versus time
C)1/[H₂O₂] versus time
D)ln[H₂O₂] versus time

Question 28

The following reaction is first order: C₂H₆ → 2 CH₃.If the rate constant is equal to 5.5 × 10^-4 s^-1 at 1000 K,how long will it take for 0.35 mol of C₂H₆ in a 1.00 L container to decrease to 0.10 mol in the same container?

A)7.6 min
B)38 min
C)106 min
D)131 min

Question 29

The following set of data was obtained by the method of initial rates for the reaction: S₂O₈^2-(aq)+ 3 I^-(aq)→ 2 SO₄^2-(aq)+ I₃^-(aq)
What is the rate law for the reaction?

A)Rate = k[S₂O₈^2-][I^-]
B)Rate = k[S₂O₈^2-][I^-]⁵
C)Rate = k[S₂O₈^2-][I^-]²
D)Rate = k[S₂O₈^2-]²[I^-]

Question 30

The following set of data was obtained by the method of initial rates for the reaction: S₂O₈^2-(aq)+ 3 I^-(aq)→ 2 SO₄^2-(aq)+ I₃^-(aq)
What is the initial rate when S₂O₈^2- is 0.15 M and I^- is 0.15 M?

A)4.10 × 10^-6 M s^-1
B)8.10 × 10^-3 M s^-1
C)1.22 × 10^-2 M s^-1
D)5.40 × 10^-2 M s^-1

Question 31

Acetaldehyde decomposes at 750 K: CH₃CHO → CO + CH₄.The reaction is first order in acetaldehyde and the half-life of the reaction is found to be 530 seconds.What is the rate constant for the reaction at this temperature?

A)2.7 × 10^-3 s^-1
B)1.3 × 10^-3 s^-1
C)2.7 × 10² s^-1
D)7.6 × 10² s^-1

Question 32

The first-order reaction,SO₂Cl₂ → SO₂ + Cl₂,has a rate constant equal to 2.20 × 10^-5 s^-1 at 593 K.What percentage of the initial amount of SO₂Cl₂ will remain after 2.00 hours?

A)1.00%
B)14.7%
C)17.1%
D)85.4%

Question 33

A zeroth order reaction is one whose

A)rate is zero.
B)rate is independent of reactant concentration.
C)rate can be found where [A]_t= -kt + ln [A]_o.
D)rate is dependent on none of the reactants.

Question 34

Which statement below regarding the half-life of a zeroth-order reaction is true?

A)Each half-life is half as long as the preceding half-life.
B)Each half-life is twice as long as the preceding half-life.
C)Each half-life is four times as long as the preceding half-life.
D)The half-life remains unchanged throughout the course of the reaction.

Question 35

The first-order reaction,2 N₂O(g)→ 2 N₂(g)+ O₂(g),has a rate constant equal to 0.76 s^-1 at 1000 K.How long will it take for the concentration of N₂O to decrease to 42% of its initial concentration?

A)0.88 s
B)1.1 s
C)1.8 s
D)2.4 s

Question 36

The following set of data was obtained by the method of initial rates for the reaction: BrO₃^-(aq)+ 5 Br^-(aq)+ 6 H⁺(aq)→ 3 Br₂(aq)+ 3 H₂O(l).
Calculate the initial rate when BrO₃^- is 0.30 M,Br^- is 0.050 M,and H⁺ is 0.15 M.

A)6.1 × 10^-5 M/s
B)2.7 × 10^-3 M/s
C)5.3 × 10^-2 M/s
D)8.4 × 10^-2 M/s

Question 37

The following set of data was obtained by the method of initial rates for the reaction: (H₃C)₃CBr + OH^- → (H₃C)₃COH + Br^-
What is the order of reaction with respect to ion,OH^-?

A)zero
B)first
C)second
D)none of these

Question 38

The following set of data was obtained by the method of initial rates for the reaction: BrO₃^-(aq)+ 5 Br^-(aq)+ 6 H⁺(aq)→ 3 Br₂(aq)+ 3 H₂O(l).
What is the rate law for the reaction?

A)Rate = k[BrO₃^-][Br^-][H⁺]⁴
B)Rate = k[BrO₃^-][Br^-][H⁺]^-4
C)Rate = k[BrO₃^-][Br^-][H⁺]^-2
D)Rate = k[BrO₃^-][Br^-][H⁺]²

Question 39

The following set of data was obtained by the method of initial rates for the reaction: (H₃C)₃CBr + OH^- → (H₃C)₃COH + Br^-
What is the value of the rate constant,k?

A)8.8 × 10^-4 s^-1
B)4.4 × 10^-4 s^-1
C)1.8 × 10^-4 s^-1
D)none of these

Question 40

For a particular first-order reaction,it takes 48 minutes for the concentration of the reactant to decrease to 25% of its initial value.What is the value for rate constant (in s^-1)for the reaction?

A)1.0 × 10^-4 s^-1
B)4.8 × 10^-4 s^-1
C)6.0 × 10^-3 s^-1
D)2.9 × 10^-2 s^-1

Question 41

In aqueous solution,hypobromite ion,BrO^-,reacts to produce bromate ion,BrO₃^-,and bromide ion,Br^-,according to the following chemical equation. 3 BrO^-(aq)→ BrO₃^-(aq)+ 2 Br^-(aq)
A plot of 1/[BrO^-] vs.time is linear and the slope is equal to 0.056 M^-1s^-1.If the initial concentration of BrO^- is 0.65 M,how long will it take one-half of the BrO^- ion to react?

A)3.6 × 10^-2 s
B)7.1 s
C)12 s
D)27

Question 42

The reaction: 2 HI → H₂ + I₂,is second order and the rate constant at 800 K is 9.70 × 10^-2 M^-1 s^-1.How long will it take for 8.00 × 10^-2 mol/L of HI to decrease to one-fourth of its initial concentration?

A)0.619 s
B)124 s
C)387 s
D)429 s

Question 43

Which part of the Arrhenius equation contains a term which measures the number of molecules that have the correct orientation for reaction?

A)activation energy
B)e^-Ea/RT
C)frequency factor
D)none of these

Question 44

What factor affects the rate of a chemical reaction?

A)collision frequency
B)fraction of collisions with sufficient energy
C)orientation of molecules
D)All of these

Question 45

A common rule in organic chemistry is that increasing the temperature of a reaction at room temperature by 10°C doubles the rate.Calculate E_a for a reaction that follows this rule.Assume room temperature is 25°C.

A)0.576 kJ
B)12.2 kJ
C)38.4 kJ
D)52.9 kJ

Question 46

What is the minimum energy barrier that must be overcome for a chemical reaction to occur?

A)activation energy
B)net energy
C)potential energy
D)rate limiting energy

Question 47

The reaction for the decomposition of dinitrogen monoxide gas to form oxygen radicals is: .If the rate constant is 3.04 × 10^-2 s^-1 and the frequency factor is 8.00 × 10¹¹ s^-1,what is the activation energy for the first-order reaction at 700°C?

A)0.262 kJ/mol
B)38.2 kJ/mol
C)180 kJ/mol
D)250 kJ/mol

Question 48

A plot of 1/[BrO^-] vs time is linear for the reaction: 3 BrO^-(aq)→ BrO₃^-(aq)+ 2 Br^-(aq)
What is the order of the reaction with respect to the hypobromite ion,BrO^-?

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

Question 49

For the hypothetical second order reaction: A → products,the general rate law is: rate = k[A]².How long is the third half-life of the reaction if [A]₀ is 0.080 M and the first half-life is 22 minutes?

A)0.57 min
B)1.7 min
C)7.3 min
D)88 min

Question 50

The second-order reaction,2 Mn(CO)₅ → Mn₂(CO)₁₀ has a rate constant equal to 3.0 × 10⁹ M^-1s^-1 at 25°C.If the initial concentration of Mn(CO)₅ is 1.0 × 10^-5 M,how long will it take for 90.% of the reactant to disappear?

A)3.3 × 10^-16 s
B)3.7 × 10^-15 s
C)3.0 × 10^-4 s
D)3.0 × 10³ s

Question 51

The reaction for the decomposition of dinitrogen monoxide gas to form an oxygen radical is: .If the activation energy is 250 kJ/mol and the frequency factor is 8.0 × 10¹¹ s^-1,what is the rate constant for the first-order reaction at 1000 K?

A)1.1 × 10^-3 s^-1
B)7.0 × 10^-2 s^-1
C)1.6 × 10¹³ s^-1
D)9.1 × 10²⁴ s^-1

Question 52

According to kinetic molecular theory,which of the following will decrease the rate of reaction?

A)increase the temperature
B)increase the concentration
C)increase the size of the molecule
D)increase the size of the reaction vessel

Question 53

Nitrogen dioxide decomposes at 300°C via a second-order process to produce nitrogen monoxide and oxygen according to the following chemical equation. 2 NO₂(g)→ 2 NO(g)+ O₂(g).
A sample of NO₂(g)is initially placed in a 2.50-L reaction vessel at 300°C.If the half-life and the rate constant at 300°C are 11 seconds and 0.54 M^-1 s^-1,respectively,how many moles of NO₂ were in the original sample?

A)0.17 mol
B)0.42 mol
C)5.9 mol
D)15 mol

Question 54

Which statement below regarding the half-life of a second-order reaction is true?

A)Each half-life is half as long as the preceding one.
B)Each half-life is twice as long as the preceding one.
C)Each half-life is four times as long as the preceding one.
D)The length of the half-life remains unchanged throughout the course of the reaction.

Question 55

A gas molecule at 298 K and 1 atm pressure undergoes a collision with another gas molecule approximately every ________ seconds.

A)10^-15
B)10^-9
C)10^-6
D)10^-3

Question 56

When the temperature of a gas whose activation energy is 55 kJ/mol is increased from 300 K to 320 K,the fraction of collisions with sufficient energy to react

A)decreases by a factor of 2.
B)decreases by a factor of 4.
C)increases by a factor of 2.
D)increases by a factor of 4.

Question 57

Consider a bimolecular reaction in the gas phase.Which one of the following changes in condition will not cause an increase in the rate of the reaction?

A)add a catalyst
B)increase the temperature at constant volume
C)increase the volume at constant temperature
D)All of these will increase the rate of reaction.

Question 58

For the first-order reaction,2 N₂O(g)→ 2 N₂(g)+ O₂(g),what is the concentration of N₂O after 3 half-lives if 0.15 mol of N₂O is initially placed into in a 1.00-L reaction vessel?

A)9.4 × 10^-3 M
B)1.9 × 10^-2 M
C)3.8 × 10^-2 M
D)7.5 × 10^-2 M

Question 59

Hydrogen iodide decomposes at 800 K via a second-order process to produce hydrogen and iodine according to the following chemical equation. 2 HI(g)→ H₂(g)+ I₂(g)
At 800 K it takes 142 seconds for the initial concentration of HI to decrease from 6.75 × 10^-2 M to 3.50 × 10^-2 M.What is the rate constant for the reaction at this temperature?

A)5.12 × 10^-4 M^-1s^-1
B)9.69 × 10^-2 M^-1s^-1
C)10.3 M^-1s^-1
D)1.95 × 10³ M^-1s^-1

Question 60

The fraction of collisions with sufficient energy to react is equal to

A)A.
B)E_a.
C)e^-Ea/RT.
D)p.

Question 61

Shown is a concentration versus time plot for a reaction involving gases A,B,and C.
Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.What is the rate of reaction with respect to A over the time interval 700 to 800 seconds?

A)0 M/s
B)less than 3.7 × 10^-5 M/s
C)3.7 × 10^-5 M/s
D)greater than 3.7 × 10^-5 M/s

Question 62

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10^-4 s ^-1 at 470°C and an activation energy of 264 kJ/mol.What is the temperature of the reaction when the rate constant is equal to 4.36 × 10^-3 s^-1?

A)126°C
B)411°C
C)510°C
D)540°C

Question 63

Which of the following does not affect the rate of a bimolecular reaction?

A)concentrations of reactants
B)presence of a catalyst
C)temperature
D)All of these affect the rate.

Question 64

The aquation of tris(1,10-phenanthroline)iron(II)in acid solution takes place according to the equation: Fe(phen)₃²⁺ + 3 H₃O⁺ + 3 H₂O → Fe(H₂O)₆²⁺ + 3 phenH⁺
If the activation energy,E_a,is 126 kJ/mol and the rate constant at 30°C is 9.8 × 10^-3 min^-1,what is the frequency factor,A?

A)2 × 10^-24 min^-1
B)2 × 10^-20 min^-1
C)5 × 10¹⁹ min^-1
D)5 × 10²³ min^-1

Question 65

The aquation of tris(1,10-phenanthroline)iron(II)in acid solution takes place according to the equation: Fe(phen)₃²⁺ + 3 H₃O⁺ + 3 H₂O → Fe(H₂O)₆²⁺ + 3 phenH⁺
If the activation energy is 126 kJ/mol and frequency factor is 8.62 × 10¹⁷ s^-1,at what temperature is the rate constant equal to 3.63 × 10^-3 s^-1 for the first-order reaction?

A)0°C
B)36°C
C)50°C
D)94°C

Question 66

The aquation of tris(1,10-phenanthroline)iron(II)in acid solution takes place according to the equation: Fe(phen)₃²⁺ + 3 H₃O⁺ + 3 H₂O → Fe(H₂O)₆²⁺ + 3 phenH⁺
If the activation energy,E_a,is 126 kJ/mol and the rate constant at 30°C is 9.8 × 10^-3 min^-1,what is the rate constant at 50°C?

A)4.4 × 10^-4 min^-1
B)2.2 × 10^-1 min^-1
C)4.6 × 10⁰ min^-1
D)2.3 × 10³ min^-1

Question 67

When the concentration of A is doubled,the rate for the reaction: 2 A + B → 2 C quadruples. When the concentration of B is doubled the rate remains the same.Which mechanism below is consistent with the experimental observations?

A)Step 1: A + B ⇌ D (fast equilibrium)
Step 2: A + D → 2 C (slow)
B)Step 1: A + B → D (slow)
Step 2: A + D ⇌ 2 C (fast equilibrium)
C)Step 1: 2 A → D (slow)
Step 2: B + D → E (fast)
Step 3: E → 2 C (fast)
D)Step 1: 2 A ⇌ D (fast equilibrium)
Step 2: B + D → E (slow)
Step 3: E → 2 C (fast)

Question 68

A three-step mechanism has been suggested for the formation of carbonyl chloride: Step 1: Cl₂→ 2 Cl (fast,equilibrium)
Step 2: Cl + CO → COCl (fast,equilibrium)
Step 3: COCl + Cl₂ → COCl₂ + Cl (slow)
What is the molecularity of the rate-determining step?

A)unimolecular
B)bimolecular
C)termolecular
D)none of these

Question 69

Which of the following statements are true about reaction mechanisms? I.A rate law can be written from the molecularity of the slowest elementary step.
II.The final rate law can include intermediates.
III.The rate of the reaction is dependent on the fastest step in the mechanism.
IV.A mechanism can never be proven to be the correct pathway for a reaction.

A)I,II,III
B)II,IV
C)I,III
D)I,IV

Question 70

The elementary reaction representing the formation of ozone: O₂(g)+ O(g)+ M(g)→ O₃(g)+ M^*(g)is an example of a ________ reaction.

A)unimolecular
B)bimolecular
C)termolecular
D)tetramolecular

Question 71

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g)+ HO(g)→ HO₂(g)+ O₂(g)
Step 2: HO₂(g)+ O(g)→ HO(g)+ O₂(g)
What is the molecularity of the overall reaction?

A)unimolecular
B)bimolecular
C)none of these because molecularity is the difference of the exponents in the rate law
D)none of these because molecularity only refers to elementary steps

Question 72

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Br + O₃ → BrO + O₂
BrO + O → Br + O₂
Which species is a catalyst in this mechanism?

A)Br
B)BrO
C)O
D)O₃

Question 73

The first-order isomerization reaction: cyclopropane → propene,has a rate constant of 1.10 × 10^-4 s^-1 at 470°C and 5.70 × 10^-4 s^-1 at 500°C.What is the activation energy,E_a,for the reaction?

A)46 kJ/mol
B)110 kJ/mol
C)260 kJ/mol
D)380 kJ/mol

Question 74

Shown is a concentration versus time plot for a reaction involving gases A,B,and C.
Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.Over the same time interval what is the rate of reaction with respect to C,Δ[C]/Δt?

A)Δ[C]/Δt = Δ[A]/Δt = 3.7 × 10^-5 M/s
B)Δ[C]/Δt = (1/4)(Δ[A]/Δt)= (1/4)(3.7 × 10^-5 M/s)= 9.2 × 10^-6 M/s
C)Δ[C]/Δt = (1/2)(Δ[A]/Δt)= (1/2)(3.7 × 10^-5 M/s)= 1.8 × 10^-5 M/s
D)Δ[C]/Δt = -(1/2)(Δ[A]/Δt)= -(1/2)(3.7 × 10^-5 M/s)= -1.8 × 10^-5 M/s

Question 75

A suggested mechanism for the decomposition of peroxide (H₂O₂)is H₂O₂ (aq)2OH (aq)
H₂O₂ (aq)+ OH (aq)H₂O (l)+ HO₂ (g)
HO₂ (g)+ OH (aq)H₂O (l)+ O₂ (g)
Which of the following correctly labels the chemical equation for the overall reaction and the reaction intermediates?

A)Overall reaction = H₂O₂ (aq)H₂O (l)+ O₂ (g),intermediates = HO₂ (aq)+ OH (aq)
B)Overall reaction = 3H₂O₂ (aq)3H₂O (l)+ O₂ (g),intermediates = OH (aq)
C)Overall reaction = 2H₂O₂ (aq)2H₂O (l)+ O₂ (g),intermediates = HO₂ (aq)+ OH (aq)
D)Overall reaction = H₂O₂ + 2OH (aq)+ HO₂ (aq)H₂O (l)+ 2OH (aq)+ O₂ (g)+ HO₂ (aq),intermediates = HO₂ (aq)+ OH (aq)

Question 76

The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: Step 1: Br + O₃ → BrO + O₂
Step 2: BrO + O → Br + O₂
Which species is an intermediate in this mechanism?

A)Br
B)BrO
C)O
D)O₃

Question 77

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g)+ HO(g)→ HO₂(g)+ O₂(g)
Step 2: HO₂(g)+ O(g)→ HO(g)+ O₂(g)
Which species is a catalyst?

A)HO
B)HO₂
C)O
D)O₃

Question 78

Shown is a concentration versus time plot for a reaction involving gases A,B,and C.
Over the time interval 300 to 400 seconds,the rate of reaction with respect to A is Δ[A]/Δt = 3.7 × 10^-5 M/s.Over the same time interval what is the rate of reaction with respect to B,Δ[B]/Δt?

A)Δ[B]/Δt = Δ[A]/Δt = 3.7 × 10^-5 M/s
B)Δ[B]/Δt = (1/4)(Δ[A]/Δt)= (1/4)(3.7 × 10^-5 M/s)= 9.2 × 10^-6 M/s
C)Δ[B]/Δt = (1/2)(Δ[A]/Δt)= (1/2)(3.7 × 10^-5 M/s)= 1.8 × 10^-5 M/s
D)Δ[B]/Δt = -(1/2)(Δ[A]/Δt)= -(1/2)(3.7 × 10^-5 M/s)= -1.8 × 10^-5 M/s

Question 79

Shown is a concentration versus time plot for a reaction involving gases A,B,and C.
Which equation best represents the reaction?

A)4A(g)→ B(g)+ 2C(g)
B)4A(g)+ B(g)→ 2C(g)
C)2C(g)→ 4A(g)+ B(g)
D)2C(g)+ B(g)→ 4A(g)

Question 80

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O₃(g)+ HO(g)→ HO₂(g)+ O₂(g)
Step 2: HO₂(g)+ O(g)→ HO(g)+ O₂(g)
Which species is an intermediate?

A)HO
B)HO₂
C)O
D)O₃