Question 1

When a catalyst is added to a reaction mixture, it

Accepted Answer

A)   increases the rate of collisions between reactant molecules.
B)   provides reactant molecules with more energy.
C)   slows down the rate of the back reaction.
D)   provides a new pathway (mechanism)  for the reaction.
E)   does none of the above.F) A) and B)
G) A) and C)

Question 2

According to the collision theory of reaction rates, what are the three requirements which must be met before an elementary reaction between two molecules can occur?

Accepted Answer

Molecules must collide with ea...

Question 3

A boiled egg can be cooked at 100.0 °C in exactly 5 minutes. At an altitude of around 2000 m where the boiling point of water is 93.0 °C, it takes exactly 7.5 minutes to cook the egg to the same amount. What is the activation energy for the reaction involved when an egg is boiled?

Accepted Answer

A)   0.5 kJ/mol
B)   4.5 kJ/mol
C)   7.9 kJ/mol
D)   66 kJ/mol
E)   >100 kJ/molF) A) and D)
G) A) and E)

Question 4

The reaction X  Y is first-order overall and first-order with respect to the reactant X. The result of doubling the initial concentration of X will be to

Accepted Answer

A)   shorten the half-life of the reaction.
B)   increase the rate constant of the reaction.
C)   decrease the rate constant of the reaction.
D)   shorten the time taken to reach equilibrium.
E)   double the initial rate.F) A) and B)
G) A) and C)

Question 5

The gas-phase conversion of 1,3-butadiene to 1,5-cyclooctadiene, 2C4H6 F1F1F1S1F1F1F10 C8H12 was studied, providing data for the plot shown, of 1/[butadiene] versus time.  a. Explain how this plot confirms that the reaction is second order.
b. Calculate the second-order rate constant, k.
c. Determine the initial concentration of 1,3-butadiene in this experiment.

Accepted Answer

a. The fact that a plot of 1/[...

Question 6

If the activation energy of a reaction decreases by 10.0 kJ/mol, from 100.0 to 90.0 kJ/mol, what effect will this have on the rate of reaction at 298K?

Accepted Answer

A)   The rate will increase, by a factor of more than 50.
B)   The rate will decrease, by a factor of more than 50.
C)   The rate will increase, by a factor of less than 50.
D)   The rate will decrease, by a factor of less than 50.
E)   The rate will not change unless temperature changes.F) D) and E)
G) A) and B)

Question 7

The decomposition of dinitrogen pentaoxide to nitrogen dioxide and oxygen follows first-order kinetics and has an activation energy of 102 kJ/mol. By what factor will the fraction of collisions with energy greater than or equal to the activation energy increase if the reaction temperature goes from 30°C to 60°C?

Accepted Answer

A)   1.00
B)   1.10
C)   2.00
D)   4.00
E)   38.4F) B) and E)
G) C) and D)

Question 8

A reaction is second-order with respect to the reactant R. Which of the following plots will produce a straight line?

Accepted Answer

A)   [R] vs. 1/time
B)   1/[R] vs. time
C)   [R]2 vs. time
D)   1/[R]2 vs. time
E)   ln[R] vs. timeF) C) and D)
G) B) and D)

Question 9

The kinetics of the decomposition of dinitrogen pentaoxide is studied at 50°C and at 75°C. Which of the following statements concerning the studies is correct?

Accepted Answer

A)   The rate at 75°C will be greater than the rate at 50°C because the activation energy will be lower at 75°C than at 50°C.
B)   The rate at 75°C will be greater than the rate at 50°C because the activation energy will be higher at 75°C than at 50°C.
C)   The rate at 75°C will be less than the rate at 50°C because the molecules at higher speeds do not interact as well as those at lower speeds.
D)   The rate at 75°C will be greater than at 50°C because the concentration of a gas increases with increasing temperature.
E)   The rate at 75°C will be greater than the rate at 50°C because the number of molecules with enough energy to react increases with increasing temperature.F) B) and E)
G) A) and B)

Question 10

Consider the reaction 2NH3(g)   N2(g)  + 3H2(g) 
If the rate [H2]/t is 0.030 mol L-1 s-1, then [NH3]/t is

Accepted Answer

A)   -0.045 mol L-1 s-1
B)   -0.030 mol L-1 s-1
C)   -0.020 mol L-1 s-1
D)   -0.010 mol L-1 s-1
E)   none of the aboveF) B) and C)
G) A) and E)

Question 11

Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. H+ + H2O2 + + H2O2   H2O+-OH (rapid equilibrium)  H2O+-OH + Br-  HOBr + H2O (slow)  HOBr + H+ + Br-  Br2 + H2O (fast)  Which of the following rate laws is consistent with the mechanism? A)  Rate = k[H2O2][H+]2[Br-] B)  Rate = k [H2O+-OH][Br-] C)  Rate = k[H2O2][H+][Br-] D)  Rate = k[HOBr][H+][Br-][H2O2] E)  Rate = k[Br-]" class="answers-bank-image d-inline" rel="preload" > H2O+-OH (rapid equilibrium) 
H2O+-OH + Br-  HOBr + H2O (slow) 
HOBr + H+ + Br-  Br2 + H2O (fast) 
Which of the following rate laws is consistent with the mechanism?

Accepted Answer

A)   Rate = k[H2O2][H+]2[Br-]
B)   Rate = k [H2O+-OH][Br-]
C)   Rate = k[H2O2][H+][Br-]
D)   Rate = k[HOBr][H+][Br-][H2O2]
E)   Rate = k[Br-]F) B) and D)
G) A) and D)

Question 12

The decomposition of SOCl2 is first-order in SOCl2. If the half-life for the reaction is 4.1 hr, how long would it take for the concentration of SOCl2 to drop from 0.36 M to 0.045 M?

Accepted Answer

A)   0.52 hr
B)   1.4 hr
C)   12 hr
D)   33 hr
E)   > 40 hrF) All of the above
G) B) and E)

Question 13

When the reaction A  B + C is studied, a plot 1/[A]t vs. time gives a straight line with a positive slope. What is the order of the reaction?

Accepted Answer

A)   zero
B)   first
C)   second
D)   third
E)   More information is needed to determine the order.F) A) and B)
G) A) and C)

Question 14

Sulfur trioxide can undergo decomposition according to the equation 2SO3  2SO2 + O2
For this reaction, rate = -0 0.5[SO3]/t = k[SO3]2. If the reaction rate is 1.75 × 10-7 mol L-1 min-1 when the concentration of sulfur trioxide is 5.4 × 10-3 mol L-1, what is the value of the rate constant k?

Accepted Answer

A)   3.2 × 10-5 L mol-1 min-1
B)   1.6 × 10-5 L mol-1 min-1
C)   6.0 × 10-3 L mol-1 min-1
D)   3.0 × 10-3 L mol-1 min-1
E)   1.6 × 10-2 L mol-1 min-1F) All of the above
G) C) and D)

Question 15

In an exothermic reaction,

Accepted Answer

A)   the forward reaction is slower than the reverse reaction.
B)   the reaction rate will speed up with time.
C)   the collision energy of the reactants will be greater than that of the products.
D)   the forward reaction will have a lower activation energy than the reverse reaction.
E)   the activation energy will change as the reaction progresses.F) D) and E)
G) B) and C)

Question 16

When the reaction A  B + C is studied, a plot of ln[A]t vs. time gives a straight line with a negative slope. What is the order of the reaction?

Accepted Answer

A)   zero
B)   first
C)   second
D)   third
E)   More information is needed to determine the order.F) C) and E)
G) None of the above

Question 17

A reactant R is being consumed in a first-order reaction. What fraction of the initial R is consumed in 4.0 half-lives?

Accepted Answer

A)   0.94
B)   0.87
C)   0.75
D)   0.13
E)   0.063F) C) and D)
G) A) and B)

Question 18

All second-order reactions are bimolecular reactions.

Accepted Answer

A) True 
 B)False

Question 19

In a reversible reaction, a catalyst will speed up the forward reaction but not affect the reverse reaction.

Accepted Answer

A) True 
 B)False

Question 20

A catalyst lowers the activation energy but does not affect the mechanism of a reaction.

Accepted Answer

A) True 
 B)False

Exam 16: Kinetics: Rates and Mechanisms of Chemical Reactions

According to the collision theory of reaction rates, what are the three requirements which must be met before an elementary reaction between two molecules can occur?

Correct Answer
verified
Molecules must collide with ea...
View Answer

A catalyst lowers the activation energy but does not affect the mechanism of a reaction.

Correct Answer
verified

Correct Answer
verified
a. The fact that a plot of 1/[...
View Answer

A boiled egg can be cooked at 100.0 °C in exactly 5 minutes. At an altitude of around 2000 m where the boiling point of water is 93.0 °C, it takes exactly 7.5 minutes to cook the egg to the same amount. What is the activation energy for the reaction involved when an egg is boiled?

Correct Answer
verified

When the reaction A  B + C is studied, a plot of ln[A]_t vs. time gives a straight line with a negative slope. What is the order of the reaction?

Correct Answer
verified

In an exothermic reaction,

Correct Answer
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If the activation energy of a reaction decreases by 10.0 kJ/mol, from 100.0 to 90.0 kJ/mol, what effect will this have on the rate of reaction at 298K?

Correct Answer
verified

A reaction is second-order with respect to the reactant R. Which of the following plots will produce a straight line?

Correct Answer
verified

When a catalyst is added to a reaction mixture, it

Correct Answer
verified

Correct Answer
verified

Consider the reaction 2NH₃(g)  N₂(g) + 3H₂(g) If the rate [H₂]/t is 0.030 mol L^-1 s^-1, then [NH₃]/t is

Correct Answer
verified

A reactant R is being consumed in a first-order reaction. What fraction of the initial R is consumed in 4.0 half-lives?

Correct Answer
verified

The reaction X  Y is first-order overall and first-order with respect to the reactant X. The result of doubling the initial concentration of X will be to

Correct Answer
verified

The kinetics of the decomposition of dinitrogen pentaoxide is studied at 50°C and at 75°C. Which of the following statements concerning the studies is correct?

Correct Answer
verified

All second-order reactions are bimolecular reactions.

Correct Answer
verified

When the reaction A  B + C is studied, a plot 1/[A]_t vs. time gives a straight line with a positive slope. What is the order of the reaction?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The decomposition of SOCl₂is first-order in SOCl₂. If the half-life for the reaction is 4.1 hr, how long would it take for the concentration of SOCl₂to drop from 0.36 M to 0.045 M?

Correct Answer
verified

In a reversible reaction, a catalyst will speed up the forward reaction but not affect the reverse reaction.

Correct Answer
verified

Exam 16: Kinetics: Rates and Mechanisms of Chemical Reactions

According to the collision theory of reaction rates, what are the three requirements which must be met before an elementary reaction between two molecules can occur?

Correct AnswerverifiedMolecules must collide with ea...View AnswerShow Answer

A catalyst lowers the activation energy but does not affect the mechanism of a reaction.

Correct AnswerverifiedShow Answer

Correct Answerverifieda. The fact that a plot of 1/[...View AnswerShow Answer

A boiled egg can be cooked at 100.0 °C in exactly 5 minutes. At an altitude of around 2000 m where the boiling point of water is 93.0 °C, it takes exactly 7.5 minutes to cook the egg to the same amount. What is the activation energy for the reaction involved when an egg is boiled?

Correct AnswerverifiedShow Answer

When the reaction A  B + C is studied, a plot of ln[A]t vs. time gives a straight line with a negative slope. What is the order of the reaction?

Correct AnswerverifiedShow Answer

In an exothermic reaction,

Correct AnswerverifiedShow Answer

If the activation energy of a reaction decreases by 10.0 kJ/mol, from 100.0 to 90.0 kJ/mol, what effect will this have on the rate of reaction at 298K?

Correct AnswerverifiedShow Answer

A reaction is second-order with respect to the reactant R. Which of the following plots will produce a straight line?

Correct AnswerverifiedShow Answer

When a catalyst is added to a reaction mixture, it

Correct AnswerverifiedShow Answer

Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. H+ + H2O2 H2O+-OH (rapid equilibrium) H2O+-OH + Br-  HOBr + H2O (slow) HOBr + H+ + Br-  Br2 + H2O (fast) Which of the following rate laws is consistent with the mechanism?

Correct AnswerverifiedShow Answer

Consider the reaction 2NH3(g)  N2(g) + 3H2(g) If the rate [H2]/t is 0.030 mol L-1 s-1, then [NH3]/t is

Correct AnswerverifiedShow Answer

A reactant R is being consumed in a first-order reaction. What fraction of the initial R is consumed in 4.0 half-lives?

Correct AnswerverifiedShow Answer

The reaction X  Y is first-order overall and first-order with respect to the reactant X. The result of doubling the initial concentration of X will be to

Correct AnswerverifiedShow Answer

The kinetics of the decomposition of dinitrogen pentaoxide is studied at 50°C and at 75°C. Which of the following statements concerning the studies is correct?

Correct AnswerverifiedShow Answer

All second-order reactions are bimolecular reactions.

Correct AnswerverifiedShow Answer

When the reaction A  B + C is studied, a plot 1/[A]t vs. time gives a straight line with a positive slope. What is the order of the reaction?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The decomposition of SOCl2 is first-order in SOCl2. If the half-life for the reaction is 4.1 hr, how long would it take for the concentration of SOCl2 to drop from 0.36 M to 0.045 M?

Correct AnswerverifiedShow Answer

In a reversible reaction, a catalyst will speed up the forward reaction but not affect the reverse reaction.

Correct AnswerverifiedShow Answer

Correct Answer
verified
Molecules must collide with ea...
View Answer

Correct Answer
verified

Correct Answer
verified
a. The fact that a plot of 1/[...
View Answer

Correct Answer
verified

When the reaction A  B + C is studied, a plot of ln[A]_t vs. time gives a straight line with a negative slope. What is the order of the reaction?

Correct Answer
verified

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

Consider the reaction 2NH₃(g)  N₂(g) + 3H₂(g) If the rate [H₂]/t is 0.030 mol L^-1 s^-1, then [NH₃]/t is

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

When the reaction A  B + C is studied, a plot 1/[A]_t vs. time gives a straight line with a positive slope. What is the order of the reaction?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The decomposition of SOCl₂is first-order in SOCl₂. If the half-life for the reaction is 4.1 hr, how long would it take for the concentration of SOCl₂to drop from 0.36 M to 0.045 M?

Correct Answer
verified

Correct Answer
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