Deck 13: Rates of Reaction

Question 1

For the reaction of the ammonium ion with nitrous acid,the net reaction is
NH₄⁺(aq)+ HNO₂(aq)→ N₂(g)+ 2H₂O(l)+ H⁺(aq)
​
If the initial concentration of nitrous acid is 1.00 M and,after 17.8 s has elapsed,the concentration of nitrous acid has fallen to 0.72 M,what is the average rate of the reaction over this time interval?

A)​-0.015 M/s
B)​0.04 M/s
C)​0.015 M/s
D)​-0.04 M/s
E)​0.096 M/s

Answer 1

​-0.015 M/s

Question 2

Ozone reacts with nitrogen dioxide to produce oxygen and dinitrogen pentoxide according to the following chemical equation:
O₃(g)+ 2NO₂(g)→ O₂(g)+ N₂O₅(g)
The rate law for this reaction is Rate = k[O₃][NO₂].If concentration is measured in moles per liter and time is measured in seconds,what are the units of k?

A)L ∙ mol^-1 ∙ s
B)L² ∙ mol^-2 ∙ s^-1
C)L ∙ mol^-1 ∙ s^-1
D)mol ∙ L^-1 ∙ s^-1
E)mol² ∙ L^-2 ∙ s^-1

Answer 2

L ∙ mol^-1 ∙ s^-1

Question 3

In the reaction 2H₂O₂(aq)→ 2H₂O(l)+ O₂(g),the initial concentration of H₂O₂ is 0.565 M and,17.0 seconds later,the concentration of H₂O₂ is 0.361 M.What is the average rate of reaction over this time interval?

A)0.012779 M/s
B)0.012608 M/s
C)0.0212 M/s
D)0.00619 M/s
E)0.00615 M/s

Answer 3

0.00619 M/s

Question 4

Which of the following statements is incorrect?

A)The rates of most chemical reactions change with time.
B)The rate constant for a reaction can be changed by changing the temperature.
C)The rate constant is dependent on the reactant concentrations.
D)In a series of stepwise reactions,the rate-determining step is the slowest one.
E)The rate of a catalyzed reaction is dependent on the concentration of the catalyst.

Question 5

A rate constant for a particular reaction is 0.0070 M^-1·s−1.What is the overall order of this reaction?
​

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

Question 6

If the rate law for a reaction is
Rate = k[ClO₃^-][I^-][H⁺]²
What are the units of k when the unit of time is seconds and the unit of concentration is moles per liter?

A)(L ∙ s)/mol
B)mol²/(L² ∙ s)
C)mol/(L ∙ s)
D)L²/(mol² ∙ s)
E)L³/(mol³ ∙ s)

Question 7

For the hypothetical reaction A + 2B → 2C + D,the initial rate of disappearance of A is 2.0 × 10^-2 mol/(L ∙ s).What is the initial rate of disappearance of B?

A)8.0 × 10^-2 mol/(L ∙ s)
B)4 × 10^-2 mol/(L ∙ s)
C)1.4 × 10^-1 mol/(L ∙ s)
D)4.0 × 10^-4 mol/(L ∙ s)
E)1.4 × 10^-2 mol/(L ∙ s)

Question 8

Which of the following statements is always true?

A)Exothermic reactions have lower activation energies than endothermic reactions.
B)The rate of a catalyzed reaction is independent of the concentration of the catalyst.
C)The rate for a reaction depends on the concentrations of all the reactants.
D)The rate constant is independent of the concentrations of the reacting species.
E)The rate law can be determined from the stoichiometric equation.

Question 9

Which of the following statements concerning the experimental determination of reaction rates is incorrect?

A)To determine reaction rates one of the reactants must be colored.
B)Monitoring changes in reactant or product physical properties is a convenient way to determine reaction rates.
C)Analysis of samples withdrawn from the reaction solution at varying times is useful for slow reactions.
D)Instrumental methods,such as visible spectroscopy,may be used to continuously measure changes in reactants or products.
E)Any method of analysis that can determine product or reactant concentrations during the course of the reaction can potentially be used to determine reaction rates.

Question 10

For the reaction
6CH₂O(aq)+ 4NH₃(aq)→ (CH₂)₆N₄(aq)+ 6H₂O(l)
The rate of the reaction may be expressed as
)What is an equivalent expression for the rate of the reaction?

A)
B)​
C)​
D)​
E)​

Question 11

For which of the following hypothetical rate laws would the units of the rate constant have the general form M^-3·time−1?

A)rate = k[A]⁴
B)rate = k
C)rate = k[A]
D)rate = k[A]²
E)rate = k[A]³

Question 12

Consider the reaction
AA + bB
DD + eE C = catalyst
The rate law is
Rate = k[A]^q[B]^r[C]s
Which of the following statements is incorrect?

A)The exponents q and r are always equal to the coefficients a and b,respectively.
B)The overall reaction order is q + r + s.
C)The exponent s must be determined experimentally.
D)The symbol k represents the rate constant.
E)The exponents q,r,and s are often integers.

Question 13

The hypochlorite ion oxidizes the iodide ion in aqueous solution as represented by the following equation:
OCl^-(aq)+ I^-(aq)→ OI^-(aq)+ Cl^-(aq)
The rate law for this reaction is Rate = k
)If time is measured in seconds and concentration is measured in moles per liter,what are the units for k?

A)mol²/(L² ∙ s)
B)L/(mol ∙ s)
C)1/s
D)L²/(mol² ∙ s)
E)mol/(L ∙ s)

Question 14

For the reaction
IO₃^-(aq)+ 5I^-(aq)+ 6H⁺(aq)→ 3I₂(aq)+ 3H₂O(l)
The rate of disappearance of I O₃^-(aq)at a particular time and concentration is 2.5× 10^-3 mol/(L · s).What is the rate of appearance of I₂(aq)?

A)8.3 × 10^-3 mol/(L ∙ s)
B)3 × 10^-3 mol/(L ∙ s)
C)-8 × 10^-3 mol/(L ∙ s)
D)8 × 10^-3 mol/(L ∙ s)
E)1 × 10^-3 mol/(L ∙ s)

Question 15

For a certain first-order reaction with the general form aA → products,the rate is 0.32 M·s−1 when the concentration of the reactant is 0.27 M.What is the rate constant for this reaction?

A)0.22 s−1​
B)1.1 s−1
C)0.32 s−1
D)3.10 s−1​
E)4.3 s−1

Question 16

The oxidation of ammonia produces nitrogen and water via the following reaction:
4NH₃(g)+ 3O₂(g)→ 2N₂(g)+ 6H₂O(l)
Suppose the rate of formation of H₂O(l)is 3.0 mol/(L ∙ s).Which of the following statements is true?

A)The rate of consumption of NH₃ is 2.0 mol/(L ∙ s).
B)The rate of consumption of O₂ is 2.0 mol/(L ∙ s).
C)The rate of formation of N₂ is 1.3 mol/(L ∙ s).
D)The rate of formation of N₂ is 2.0 mol/(L ∙ s).
E)The rate of consumption of NH₃ is 0.50 mol/(L ∙ s).

Question 17

Which of the following statements is true concerning the reaction given below?
2H₂S(g)+ O₂(g)→ 2S(s)+ 2H₂O(g)

A)The rate law is Rate = k[H₂S]²[O₂].
B)The reaction is second-order in H₂S(g)and first-order in O₂(g).
C)The reaction is first-order in H₂S(g)and second-order in O₂(g).
D)The rate law is Rate = k[H₂S][O₂].
E)The rate law may be determined only by experiment.

Question 18

For the reaction
2N₂O₅(g)→ 4NO₂(g)+ O₂(g)
Which of the following expressions is equal to the rate of the reaction?

A)
B)​
C)​
D)​
E)​

Question 19

Which of the following experimental methods cannot be used to measure the rate of a reaction?

A)measurement of the absorbance of a colored reactant with time
B)measurement of the change in the partial pressure of a gas-phase product over time
C)measurement of the equilibrium concentration of an acidic product via titration with a strong base
D)measurement of the absorbance of a colored product with time
E)measurement of the change in the partial pressure of a gas-phase reactant over time

Question 20

For a second-order reaction,what are the possible units of the rate constant?

A)L^-1 ∙ s^-1
B)mol ∙ L^-1 ∙ s^-1
C)s
D)L^.mol^-1·s^-1
E)mol ∙ L^-1

Question 21

In aqueous solution,iodine reacts with acetone as represented by the following equation:
I₂(aq)+ CH₃COCH₃(aq)→ CH₃COCH₂I(aq)+ H⁺(aq)+ I^-(aq)
The experimental rate law is Rate = k[H⁺][CH₃COCH₃].According to the information above,an increase in the hydrogen ion concentration has what effect on the reaction?

A)It decreases the rate of the reaction.
B)It increases the rate of the reaction.
C)It decreases the value of the equilibrium constant.
D)It increases the value of the equilibrium constant.
E)It does not affect the rate of the reaction.

Question 22

The following data were obtained in a kinetics study of the hypothetical reaction A + B + C → products.
[A]₀ (M)
[B]₀ (M)
[C]₀ (M)
Initial Rate (10^-3 M/s)
0)4
0)4
0)2
160
0)2
0)4
0)4
80
0)6
0)1
0)2
15
0)2
0)1
0)2
5
0)2
0)2
0)4
20
Using the initial-rate method,what is the order of the reaction with respect to C?

A)zero-order
B)first-order
C)third-order
D)second-order
E)impossible to tell from the data given

Question 23

The reaction
2H₂(g)+ 2NO(g)→ 2H₂O(g)+ N₂(g)
Is first-order in H₂ and second-order in NO at a particular temperature.What is the rate law?

A)Rate = k[H₂]²[NO]²
B)Rate = k[H₂][NO]²
C)Rate = k[H₂][NO]
D)Rate = k[H₂O]²[N₂]
E)Rate = k[H₂]²[NO]

Question 24

If a reaction is first-order with respect to a particular reactant,when the concentration of that reactant is increased by a factor of 2,the reaction rate will _____.

A)increase by a factor of 2.
B)remain constant.
C)decrease by a factor of .
D)increase by a factor of 8.
E)increase by a factor of 4.

Question 25

The reaction between selenous acid and the iodide ion in acid solution is
H₂SeO₃(aq)+ 6I^-(aq)+ 4H⁺(aq)→ Se(s)+ 2I₃^-(aq)+ 3H₂O(l)
The data in the following table were measured at 0°C.
Experiment
[H₂SeO₃]₀ (M)
[H⁺]₀ (M)
[I^-]₀ (M)
Initial Rate [mol/(L ∙ s)]
1
1)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
5)30 × 10^-7
2
2)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
1)06 × 10^-6
3
3)00 × 10^-4
4)00 × 10^-2
3)00 × 10^-2
6)36 × 10^-6
4
3)00 × 10^-4
8)00 × 10^-2
3)00 × 10^-2
2)54 × 10^-5
5
3)00 × 10^-4
8)00 × 10^-2
6)00 × 10^-2
2)04 × 10^-4
6
2)00 × 10^-4
2)00 × 10^-2
6)00 × 10^-2
8)48 × 10^-6
Tripling the initial concentration of H₂SeO₃ while holding the initial concentrations of H⁺ and I^- constant increases the rate of the reaction by a factor of

A)8.
B)4.
C)3.
D)2.
E)1.

Question 26

Nitrosyl chloride is produced from the reaction of nitrogen monoxide and chlorine:
2NO(g)+ Cl₂(g)→ 2NOCl(g)
The following initial rates at a given temperature were obtained for the concentrations listed below.
Experiment
Initial Rate (mol·L^-1·h^-1)
[NO]₀ (mol·L^-1)
[Cl₂]₀ (mol·L^-1)
1
2)21
0)25
0)25
2
19)89
0)75
0)25
3
6)63
0)25
0)75
From the data,what is the experimental rate law?

A)Rate = k[Cl₂]
B)Rate = k[NO]
C)Rate = k[NO][Cl₂]²
D)Rate = k[NO]²[Cl₂]
E)Rate = k[NO][Cl₂]^1/2

Question 27

The rate law for the chemical reaction
5Br^-(aq)+ BrO₃^-(aq)+ 6H⁺(aq)→ 3Br₂(aq)+ 3H₂O(l)
Has been determined experimentally to be Rate = k[Br^-][BrO₃^-][H⁺]².What is the overall order of the reaction?

A)3
B)5
C)4
D)2
E)1

Question 28

For the reaction A + B + C → products,the following initial-rate data were obtained.
[A]₀ (mol/L)
[B]₀ (mol/L)
[C]₀ (mol/L)
Initial Rate (mol/(L ∙ s))
0)40
0)40
0)20
0)0160
0)20
0)40
0)40
0)0080
0)60
0)10
0)20
0)0015
0)20
0)10
0)20
0)0005
0)20
0)20
0)40
0)0020
What are the reaction orders with respect to A,B,and C,respectively?

A)0,1,1
B)1,2,1
C)1,1,1
D)1,2,0
E)0,2,1

Question 29

For the reaction
(CH₃)₃CCl(aq)+ OH^-(aq)→ (CH₃)₃COH(aq)+ Cl^-(aq)
It is found experimentally that doubling the initial concentration of (CH₃)₃CCl causes the initial reaction rate to double,but doubling the initial concentration of OH^- has no effect on the rate.What is the rate law?

A)Rate = k[(CH₃)₃CCl]²[OH^-]
B)Rate = k[(CH₃)₃CCl][OH^-]
C)Rate = k
D)Rate = k[(CH₃)₃COH][Cl^-]
E)Rate = k[(CH₃)₃CCl]

Question 30

The reaction between selenous acid and the iodide ion in acid solution is
H₂SeO₃(aq)+ 6I^-(aq)+ 4H⁺(aq)→ Se(s)+ 2I₃^-(aq)+ 3H₂O(l)
The data in the following table were measured at 0°C.
Experiment
[H₂SeO₃]₀ (M)
[H⁺]₀ (M)
[I^-]₀ (M)
Initial Rate [mol/(L ∙ s)]
1
1)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
5)30 × 10^-7
2
2)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
1)06 × 10^-6
3
3)00 × 10^-4
4)00 × 10^-2
3)00 × 10^-2
6)36 × 10^-6
4
3)00 × 10^-4
8)00 × 10^-2
3)00 × 10^-2
2)54 × 10^-5
5
3)00 × 10^-4
8)00 × 10^-2
6)00 × 10^-2
2)04 × 10^-4
6
2)00 × 10^-4
2)00 × 10^-2
6)00 × 10^-2
8)48 × 10^-6
What is the rate constant for this reaction?

A)1.5 × 10⁴ L⁵/(mol⁵ ∙ s)
B)1.5 × 10¹⁰ L⁵/(mol⁵ ∙ s)
C)4.9 × 10⁵ L⁵/(mol⁵ ∙ s)
D)294 L⁵/(mol⁵ ∙ s)
E)8.8 L⁵/(mol⁵ ∙ s)

Question 31

Two substances A and B react with each other in such a way that one-half of A remains after 25 min and one-fourth of A remains after 50 min.Doubling the concentration of B while keeping the concentration of A fixed doubles the rate of the reaction.This reaction is

A)first-order in both A and B.
B)zero-order in both A and B.
C)second-order in A and first-order in B.
D)first-order in A and second-order in B.
E)second-order in both A and B.

Question 32

The following data were obtained for the hypothetical reaction 2A + B → products.

What is the overall order of this reaction?

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

Question 33

If a reaction is zero-order in a reactant,when the concentration of the reactant is decreased by a factor of 2,the reaction rate will

A)quadruple.
B)decrease by a factor of 1/2.
C)remain constant.
D)decrease by a factor of 1/4.
E)double.

Question 34

The rate law for the hydrolysis of thioacetamide (CH₃CSNH₂),
CH₃CSNH₂(aq)+ H₂O(l)→ H₂S(g)+ CH₃CONH₂(aq)
Is Rate = k[H⁺][CH₃CSNH₂].If,during the course of the reaction,some solid sodium hydroxide is added to the reaction mixture,then

A)the reaction rate decreases,but k remains the same.
B)the reaction rate remains the same,but k decreases.
C)the reaction rate increases,but k remains the same.
D)there is no change in the reaction rate or the rate constant.
E)the reaction rate remains the same,but k increases.

Question 35

The acid-catalyzed reaction of acetone,CH₃COCH₃,with iodine can be represented by the following net reaction:
CH₃COCH₃ + I₂
CH₂ICOCH₃ + H⁺ + I^-
It is found experimentally that the rate law for this reaction is Rate = k[CH₃COCH₃][H⁺].Suppose that in trial 1,the initial rate of the reaction is measured with the initial concentrations of acetone,iodine,and hydrogen ion all equal to 0.10 M.Then,in trial 2,the initial rate of the reaction is measured with the initial concentrations all equal to 0.20 M.The initial rate of trial 2 will be larger than the initial rate of trial 1 by a factor of

A)4.
B)16.
C)8.
D)2.
E)64.

Question 36

For the reaction between nitrogen monoxide and chlorine to produce nitrosyl chloride,2NO(g)+ Cl₂(g)→ 2NOCl(g),it is found that tripling the initial concentration of both reactants increases the initial rate by a factor of 27.If only the initial concentration of chlorine is tripled,the initial rate increases by a factor of 3.What is the order of the reaction with respect to Cl₂?

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

Question 37

The balanced chemical equation and rate law for the reaction between NO(g)and H₂(g)at a particular temperature are
2NO(g)+ 2H₂(g)→ N₂(g)+ 2H₂O(g)
Rate = k[NO]²[H₂]
What is the reaction order with respect to nitric oxide?

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

Question 38

The hypochlorite ion oxidizes the iodide ion in aqueous solution as represented by the following equation:
OCl^-(aq)+ I^-(aq)→ OI^-(aq)+ Cl^-(aq)
The rate law for this reaction is Rate = k
)The overall reaction order and the order with respect to OH^- are

A)2 and -1.
B)0 and -1.
C)0 and 1.
D)2 and 1.
E)1 and -1.

Question 39

The reaction between selenous acid and the iodide ion in acid solution is
H₂SeO₃(aq)+ 6I^-(aq)+ 4H⁺(aq)→ Se(s)+ 2I₃^-(aq)+ 3H₂O(l)
The data in the following table were measured at 0°C.
Experiment
[H₂SeO₃]₀ (M)
[H⁺]₀ (M)
[I^-]₀ (M)
Initial Rate [mol/(L ∙ s)]
1
1)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
5)30 × 10^-7
2
2)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
1)06 × 10^-6
3
3)00 × 10^-4
4)00 × 10^-2
3)00 × 10^-2
6)36 × 10^-6
4
3)00 × 10^-4
8)00 × 10^-2
3)00 × 10^-2
2)54 × 10^-5
5
3)00 × 10^-4
8)00 × 10^-2
6)00 × 10^-2
2)04 × 10^-4
6
2)00 × 10^-4
2)00 × 10^-2
6)00 × 10^-2
8)48 × 10^-6
The overall order of this reaction is

A)4.
B)6.
C)2.
D)8.
E)3.

Question 40

The rate law for the reaction between chlorine and nitric oxide,
2NO(g)+ Cl₂(g)→ 2NOCl(g)
Is Rate = k[NO]²[Cl₂].Which of the following changes will not alter the initial rate of the reaction?

A)increasing the concentration of NOCl
B)decreasing the volume of the reaction system
C)running the reaction in a solvent rather than in the gas phase
D)increasing the volume of the reaction system
E)increasing the concentration of chlorine gas

Question 41

The gas-phase decomposition of N₂O₅ is a first-order process with a rate constant of 1.50 × 10^-3 s^-1 at 55°C.The decomposition reaction is
N₂O₅(g)→ 2NO₂(g)+
O₂(g)
If 8.0 g of N₂O₅ is placed in vessel 1 and 16.0 g of N₂O₅ in vessel 2 and the vessels are at the same temperature (55°C)and the same pressure,how much time is required for half of the N₂O₅ to decompose in each vessel?

A)Vessel 1 requires the same amount of time as vessel 2.
B)Vessel 1 requires twice as much time as vessel 2.
C)Vessel 1 requires three times as much time as vessel 2.
D)Vessel 1 requires four times as much time as vessel 2.
E)Vessel 2 requires twice as much time as vessel 1.

Question 42

The reaction between selenous acid and the iodide ion in acid solution is
H₂SeO₃(aq)+ 6I^-(aq)+ 4H⁺(aq)→ Se(s)+ 2I₃^-(aq)+ 3H₂O(l)
The data in the following table were measured at 0°C.
Experiment
[H₂SeO₃]₀ (M)
[H⁺]₀ (M)
[I^-]₀ (M)
Initial Rate [mol/(L ∙ s)]
1
1)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
5)30 × 10^-7
2
2)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
1)06 × 10^-6
3
3)00 × 10^-4
4)00 × 10^-2
3)00 × 10^-2
6)36 × 10^-6
4
3)00 × 10^-4
8)00 × 10^-2
3)00 × 10^-2
2)54 × 10^-5
5
3)00 × 10^-4
8)00 × 10^-2
6)00 × 10^-2
2)04 × 10^-4
6
2)00 × 10^-4
2)00 × 10^-2
6)00 × 10^-2
8)48 × 10^-6
Tripling the initial concentration of I^- while holding the initial concentrations of H₂SeO₃ and H⁺ constant increases the initial rate of the reaction by a factor of

A)27.
B)9.
C)3.
D)8.
E)6.

Question 43

A reaction that is second-order in one reactant has a rate constant of 3.8 × 10^-2 L/(mol ∙ s).If the initial concentration of the reactant is 0.280 mol/L,how long will it take for the concentration to become 0.140 mol/L?

A)180 s
B)47 s
C)930 s
D)18 s
E)93 s

Question 44

For the hypothetical first-order reaction A → products,k = 0.0822 s^-1.If the initial concentration of A is 0.372 M,how long would it take for A to be 28.2% consumed?

A)8.43 s
B)4.03 s
C)12 s
D)32.7 s
E)15.3 s

Question 45

For the hypothetical second-order reaction A → products,k = 0.379 M^-1 s^-1.If the initial concentration of A is 0.799 M,how long would it take for A to be 39.7% consumed?

A)5.01 s
B)3.3129 s
C)1.33 s
D)2 s
E)2.43 s

Question 46

A chemical reaction that is first-order in X is observed to have a rate constant of 2.00 × 10^-2 s^-1.If the initial concentration of X is 1.0 M,what is the concentration of X after 196 s?

A)0.20 M
B)0.020 M
C)50 M
D)0.61 M
E)0.98 M

Question 47

The radioactive nuclide ⁶³Ni decays by a first-order process via the emission of a beta particle.The ⁶³Ni nuclide has a half-life of 100.years.How long will it take for 71% of ⁶³Ni to decay?

A)49.4 years
B)21.4 years
C)0.857 years
D)178 years
E)77.5 years

Question 48

The nuclide ¹⁸⁸W decays by a first-order process with a rate constant of 1.0 × 10^-2 d^-1.How long will it take for 88% of the initial amount of ¹⁸⁸W to be consumed?

A)6 d
B)240 d
C)12 d
D)210 d
E)92 d

Question 49

The reaction between selenous acid and the iodide ion in acid solution is
H₂SeO₃(aq)+ 6I^-(aq)+ 4H⁺(aq)→ Se(s)+ 2I₃^-(aq)+ 3H₂O(l)
The data in the following table were measured at 0°C.
Experiment
[H₂SeO₃]₀ (M)
[H⁺]₀ (M)
[I^-]₀ (M)
Initial Rate [mol/(L ∙ s)]
1
1)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
5)30 × 10^-7
2
2)00 × 10^-4
2)00 × 10^-2
3)00 × 10^-2
1)06 × 10^-6
3
3)00 × 10^-4
4)00 × 10^-2
3)00 × 10^-2
6)36 × 10^-6
4
3)00 × 10^-4
8)00 × 10^-2
3)00 × 10^-2
2)54 × 10^-5
5
3)00 × 10^-4
8)00 × 10^-2
6)00 × 10^-2
2)04 × 10^-4
6
2)00 × 10^-4
2)00 × 10^-2
6)00 × 10^-2
8)48 × 10^-6
Tripling the initial concentration of H⁺ while holding the initial concentrations of H₂SeO₃ and I^- constant increases the initial rate of the reaction by a factor of

A)9.
B)16.
C)32.
D)2.
E)4.

Question 50

The half-life of a reaction is

A)twice as long for a second-order reaction as it is for a first-order reaction.
B)one-half of the time the reaction will take to go to completion.
C)how long the reaction can run before stopping.
D)the time it takes for the amount of product formed to equal half the initial amount of reactant.
E)the time it takes for the reactant concentration to decrease to one-half of its initial value.

Question 51

At a given temperature,a first-order reaction has a rate constant of 2.5 × 10^-3 s^-1.How long will it take for the reaction to be 35% complete?

A)410 s
B)1600 s
C)1400 s
D)74 s
E)170 s

Question 52

Which of the following is not a correct representation of the integrated rate expression for a first-order reaction?

A)
B)
C)
D)
E)

Question 53

At 500^oC,cyclopropane (C₃H₆)reacts to form its isomer,propene (C₃H₆).The reaction is first-order,and the rate constant is 6.7 × 10^-4 s^-1.If the initial concentration of cyclopropane is 0.500 M and the initial concentration of propene is 0,determine the time required for the concentration of propene to reach 0.100 M.

A)3.4 × 10³ s
B)3.3 × 10² s
C)1.2 × 10⁴ s
D)7.5 × 10² s
E)2.4 × 10³ s

Question 54

The reaction 3NO → N₂O + NO₂ is found to obey the rate law Rate = k[NO]².If the first half-life of the reaction is found to be 2.0 s,what is the length of the fourth half-life?

A)4.0 s
B)8.0 s
C)2.0 s
D)16.0 s
E)12.0 s

Question 55

A second-order reaction starts with an initial concentration of 0.100 mol/L of the reactant.If the rate constant is 2.4× 10^-2 L/(mol ∙ s),what is the time required to decrease the initial concentration to 0.050 mol/L?

A)410 s
B)620 s
C)28.9 s
D)2.08 s
E)1200 s

Question 56

The reaction A → products is first-order in A.If the concentration of A is cut in half,the half-life of the reaction will

A)decrease by a factor of 1/2.
B)double.
C)decrease by a factor of 1/4.
D)remain constant.
E)quadruple.

Question 57

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

A)second-order reaction only
B)first-order reaction only
C)zero-order reaction only
D)all of the above
E)none of the above

Question 58

The nuclide ⁹⁶Nb decays by a first-order process with a rate constant of 2.96 × 10^-2 h^-1.How long will it take for 86.0% of the initial amount of ⁹⁶Nb to be consumed?

A)33.7 h
B)66.4 h
C)30 h
D)5.09 h
E)4.72 h

Question 59

Dinitrogen tetroxide decomposes to form nitrogen dioxide in a second-order reaction:
N₂O₄(g)→ 2NO₂(g)
At 400.0 K,the rate constant for this reaction has been measured to be 2.9 × 10⁸ L/(mol ∙ s).Suppose 0.742 mol of N₂O₄(g)is placed in a sealed 34.3-L container at 400.0 K and allowed to react.What is the total pressure inside the vessel after 49.6 ns has elapsed? (R= 0.0821 (L ∙ atm)/(K ∙ mol))

A)​0.879 atm
B)​0.7138 atm
C)0.541​ atm
D)2.13​ atm
E)1.42​ atm

Question 60

Which of the following corresponds to the correct integrated expression for a second-order reaction?

A)
B)
C)
D)
E)

Question 61

For the hypothetical reaction A → products,the concentration of A was monitored over time.From the following graph,what is the rate constant for the decomposition of A?

A)-0.02735 s^-1
B)2.3026 s^-1
C)-2.3026 s^-1
D)0.02735 s^-1
E)0.01188 s^-1

Question 62

Which of the following corresponds to the correct equation for the half-life of a first-order reaction?

A)
B)
C)
D)
E)

Question 63

Which of the following is not a postulate of collision theory?

A)Reactant molecules must collide to react.
B)Reactant molecules must collide with a certain minimum energy in order to form products.
C)Reactant molecules must collide with the correct orientation in order to form products.
D)The rate constant is directly proportional to the energy of activation.
E)The maximum in the potential energy curve,the activation energy,is determined by the structure of the activated complex or transition state.

Question 64

For the following reaction producing 1 mol of oxygen gas at a particular temperature,ΔH = -200 kJ.
NO(g)+ O₃(g)→ NO₂(g)+ O₂(g)
The activation energy is 11 kJ/mol.What is the activation energy for the reverse reaction?

A)11 kJ/mol
B)200 kJ/mol
C)222 kJ/mol
D)188 kJ/mol
E)211 kJ/mol

Question 65

The main reason for the increase in reaction rate with temperature is that

A)the fraction of high-energy molecules increases exponentially with temperature.
B)the activation energy increases rapidly with temperature.
C)a 10°C temperature rise results in the rate doubling.
D)there is a dramatic increase in the number of collisions.
E)heat acts as a catalyst.

Question 66

For the first-order reaction
1/2 N₂O₄(g)→ NO₂(g); ΔH = 28.6 kJ
The activation energy is 53.7 kJ/mol.What is the activation energy for the reverse reaction?

A)15.2 kJ/mol
B)82.3 kJ/mol
C)-53.7 kJ/mol
D)25.1 kJ/mol
E)53.7 kJ/mol

Question 67

Which of the following statements best describes the condition(s)needed for a successful formation for a product according to the collision model?

A)The relative orientation of the particles has an effect only if the kinetic energy of the particles is below some minimum value.
B)The collision must involve a sufficient amount of energy,provided from the motion of the particles,to overcome the activation energy.
C)The relative orientation of the particles must allow for formation of the new bonds in the product.
D)The energy of the incoming particles must be above a certain minimum value,and the relative orientation of the particles must allow for formation of new bonds in the product.
E)The relative orientation of the particles has little or no effect on the formation of the product.

Question 68

When the concentrations of the reactants are increased,the rate of the reaction increases.This is best explained by

A)an increase in the fraction of molecules that have enough energy to react.
B)an increase in the rate constant.
C)an increase in the average potential energy of the molecules.
D)an increase in the frequency of the molecular collisions.
E)an increase in the kinetic energy of the molecules.

Question 69

The rates of most chemical reactions are sensitive to a change in the temperature of the reaction system.The increase in rate as the temperature increases is best explained by

A)an increase in the collision frequency.
B)an increase in the number of high-energy molecules.
C)a decrease in the collision frequency.
D)an increase in the activation energy.
E)a decrease in the activation energy.

Question 70

For a certain reaction of the general form aA → products,the experimental data plotted as 1/[A] versus time is linear.The slope of this plot must equal

A)-1.
B)the rate constant.
C)one over the rate constant.
D)the negative of the rate constant.
E)1.

Question 71

The OH· radical disproportionates according to the elementary chemical reaction This reaction is second-order in OH·.The rate constant for the reaction is 2.0 × 10^-12 cm³/molecules at room temperature.If the initial OH· concentration is 1.4 × 10¹³ molecules/cm³,what is the first half-life for the reaction?

A)2.8 × 10¹ s
B)3.6 × 10^-2 s
C)1.8 × 10^-2 s
D)3.5 × 10¹¹ s
E)7.1 × 10^-14 s

Question 72

For a certain reaction of the general form aA → products,a plot of the experimental data as [A] versus time is linear.What is the reaction order with respect to reactant A?

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

Question 73

For the hypothetical reaction aA → products,the concentration of A was monitored with time.Given the following graph of the experimental data,what is the rate constant for the loss of reactant A?

A)2.42 μΜ ⁻¹⋅min−1
B)400.00 μΜ ⁻¹⋅min−1
C)-2.42 μΜ ⁻¹⋅min−1
D)-400 μΜ ⁻¹⋅min−1
E)24.2 μΜ ⁻¹⋅min−1

Question 74

The rate constant for a first-order reaction is 1.5× 10^-2 s^-1 at 710 K and 4.1 × 10^-2 s^-1 at 884 K.What is the activation energy? (R = 8.31 J/(mol · K))

A)12 kJ/mol
B)13 kJ/mol
C)29 kJ/mol
D)3600 kJ/mol
E)30 kJ/mol

Question 75

For the hypothetical reaction A → products,the concentration of A was monitored with time.From the following graph,what is the rate constant for the decomposition of A?

A)-0.07238 M^-1 s^-1
B)-10.00 M^-1 s^-1
C)0.07238 M^-1 s^-1
D)10.00 M^-1 s^-1
E)0.007238 M^-1 s^-1

Question 76

In a first-order reaction,the half-life is 139 minutes.What is the rate constant?

A)1.20 × 10^-4 s^-1
B)5770 s^-1
C)0.299 s^-1
D)4.99 × 10^-3 s^-1
E)8.31 × 10^-5 s^-1

Question 77

What would happen if the kinetic energy of the reactants were not enough to provide the needed activation energy?

A)The rate of the reaction would tend to increase.
B)The reactants would continue to exist in their present form.
C)The activated complex would be converted into products.
D)The products would be produced at a lower energy state.
E)The products would form at an unstable energy state.

Question 78

For the formation of 1 mol of nitrosyl chloride at a given temperature,ΔH = -38 kJ.
NO(g)+ 1/2 Cl₂(g)→ NOCl(g)
The activation energy for this reaction is 69 kJ/mol.What is the activation energy for the reverse reaction?

A)69 kJ/mol
B)31 kJ/mol
C)107 kJ/mol
D)-38 kJ/mol
E)-107 kJ/mol

Question 79

For the hypothetical reaction aA → products,the experimental data showed the following behavior (below).What is the reaction order with respect to reactant A?

A)first-order
B)second-order
C)zero-order
D)third-order
E)fourth-order

Question 80

A first-order chemical reaction is observed to have a rate constant of 24 min^-1.What is the corresponding half-life for the reaction?

A)1.7 s
B)1.7 min
C)35 min
D)2.5 s
E)34.3 s