Question 1

The reaction of ethylene (C2H4)  with butadiene (C4H6=)  to form cyclohexene (C6H10)  has an activation energy (Ea)  of 115 kJ/mol. The reverse reaction (decomposition of cyclohexene to ethylene and butadiene)  has an activation energy of 287 kJ/mol. What is the heat of reaction, Δ Hrxn, for the forward reaction?

Accepted Answer

A)   +115 kJ/mol
B)   +287 kJ/mol
C)   -287 kJ/mol
D)   +172 kJ/mol
E)   -172 kJ/mol

Question 2

In going from room temperature (25.0°C)  to 10°C above room temperature, the rate of a reaction doubles. Calculate the activation energy for the reaction.

Accepted Answer

A)   157.2 kJ/mol
B)   103.8 kJ/mol
C)   52.9 kJ/mol
D)   6.4 kJ/mol
E)   <1 kJ/mol

Question 3

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.

Question 4

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 1020 molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

Accepted Answer

A)   1.00 × 104 molecules
B)   2.00 × 1019 molecules
C)   3.20 × 1016 molecules
D)   5.00 × 1020 molecules
E)   None of these choices are correct.

Question 5

For the reaction 3A(g)  + 2B(g)  → 2C(g)  + 2D(g) 
The following data were collected at constant temperature. Determine the correct rate law for this reaction.
Trial Initial [A] Initial [B] Initial Rate
(mol/L)  (mol/L)  (mol/(L·min) ) 
1 0) 200 0.100 6.00 × 10-2
2 0) 100 0.100 1.50 × 10-2
3 0) 200 0.200 1.20 × 10-1
4 0) 300 0.200 2.70 × 10-1

Accepted Answer

A)   Rate = k[A][B]
B)   Rate = k[A][B]2
C)   Rate = k[A]3[B] 2
D)   Rate = k[A]1.5[B]
E)   Rate = k[A] 2[B]

Question 6

A reaction is first-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. time

Question 7

Consider the reaction 2NH3(g)  → N2(g)  + 3H2(g) 
If the rate Δ[H2]/Δt is 0.030 mol L-1s-1, then Δ[NH3 ]/Δt 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 these choices are correct.

Question 8

The active ingredient in an over the counter pain killer analgesic decomposes with a rate constant, k = 9.05 × 10-4 day-1. How many days does it take for 15% of the original ingredient to decompose?

Accepted Answer

A)   730 days
B)   414 days
C)   365 days
D)   180 days
E)   78 days

Question 9

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. time

Question 10

The half-life of a first-order reaction does not depend on the initial concentration of reactant.

Accepted Answer

A) True 
 B)False

Question 11

Consider the following reaction 8A(g)  + 5B(g)  → 8C(g)  + 6D(g) 
If [C] is increasing at the rate of 4.0 mol L-1s-1, at what rate is [B] changing?

Accepted Answer

A)   -0.40 mol L-1s-1
B)   -2.5 mol L-1s-1
C)   -4.0 mol L-1s-1
D)   -6.4 mol L-1s-1
E)   None of these choices are correct.

Question 12

Chlorine atoms act as heterogeneous catalysts in the destruction of ozone in the stratosphere.

Accepted Answer

A) True 
 B)False

Question 13

A catalyst accelerates a reaction because

Accepted Answer

A)   it increases the number of molecules with energy equal to or greater than the activation energy.
B)   it lowers the activation energy for the reaction.
C)   it increases the number of collisions between molecules.
D)   it increases the temperature of the molecules in the reaction.
E)   it supplies energy to reactant molecules.

Question 14

Ammonia will react with oxygen in the presence of a copper catalyst to form nitrogen and water. From 164.5°C to 179.0°C, the rate constant increases by a factor of 4.27. What is the activation energy of this oxidation reaction?

Accepted Answer

A)   24.5 kJ/mol
B)   165 kJ/mol
C)   242 kJ/mol
D)   1630 kJ/mol
E)   > 104 kJ/mol

Question 15

A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 × 10-4 mol L-1 and the rate constant k = 1.08 × 10-6 s-1, what concentration of R remains after 25 days?

Accepted Answer

A)   1.0 × 10-3 mol L-1
B)   1.0 × 10-4 mol L-1
C)   9.6 × 10-5 mol L-1
D)   4.3 × 10-5 mol L-1
E)   9.7 × 10-6 mol L-1

Question 16

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)   38.4

Question 17

The units of the rate constant depend on the order of the reaction.

Accepted Answer

A) True 
 B)False

Question 18

In order to obtain the activation energy of a reaction using a graphical method, __________ is plotted against _________, giving a straight line whose slope is equal to __________.

Accepted Answer

A)   k; T; -Ea
B)   k; 1/T; -Ea
C)   lnk; T; -Ea/R
D)   k; 1/T; -Ea/R
E)   lnk; 1/T; -Ea/R

Exam 16: Kinetics Rates and Mechanisms of Chemical Reactions

Correct Answer
verified

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 first-order with respect to the reactant R. Which of the following plots will produce a straight line?

Correct Answer
verified

Chlorine atoms act as heterogeneous catalysts in the destruction of ozone in the stratosphere.

Correct Answer
verified

A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 × 10^-4 mol L^-1 and the rate constant k = 1.08 × 10^-6 s^-1, what concentration of R remains after 25 days?

Correct Answer
verified

Ammonia will react with oxygen in the presence of a copper catalyst to form nitrogen and water. From 164.5°C to 179.0°C, the rate constant increases by a factor of 4.27. What is the activation energy of this oxidation reaction?

Correct Answer
verified

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 10²⁰ molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

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

Correct Answer
verified

The active ingredient in an over the counter pain killer analgesic decomposes with a rate constant, k = 9.05 × 10^-4 day^-¹. How many days does it take for 15% of the original ingredient to decompose?

Correct Answer
verified

In going from room temperature (25.0°C) to 10°C above room temperature, the rate of a reaction doubles. Calculate the activation energy for the reaction.

Correct Answer
verified

Correct Answer
verified

The units of the rate constant depend on the order of the reaction.

Correct Answer
verified

In order to obtain the activation energy of a reaction using a graphical method, ______ is plotted against _, giving a straight line whose slope is equal to ______.

Correct Answer
verified

A catalyst accelerates a reaction because

Correct Answer
verified

Consider the reaction 2NH₃(g) → N₂(g) + 3H₂(g) If the rate Δ[H₂]/Δt is 0.030 mol L_-1s_-1, then Δ[NH₃ ]/Δt is

Correct Answer
verified

The half-life of a first-order reaction does not depend on the initial concentration of reactant.

Correct Answer
verified

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L^-1s^-1, at what rate is [B] changing?

Correct Answer
verified

Exam 16: Kinetics Rates and Mechanisms of Chemical Reactions

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 first-order with respect to the reactant R. Which of the following plots will produce a straight line?

Correct AnswerverifiedShow Answer

Chlorine atoms act as heterogeneous catalysts in the destruction of ozone in the stratosphere.

Correct AnswerverifiedShow Answer

A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 × 10-4 mol L-1 and the rate constant k = 1.08 × 10-6 s-1, what concentration of R remains after 25 days?

Correct AnswerverifiedShow Answer

Ammonia will react with oxygen in the presence of a copper catalyst to form nitrogen and water. From 164.5°C to 179.0°C, the rate constant increases by a factor of 4.27. What is the activation energy of this oxidation reaction?

Correct AnswerverifiedShow Answer

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 1020 molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

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

Correct AnswerverifiedShow Answer

The active ingredient in an over the counter pain killer analgesic decomposes with a rate constant, k = 9.05 × 10-4 day-1. How many days does it take for 15% of the original ingredient to decompose?

Correct AnswerverifiedShow Answer

In going from room temperature (25.0°C) to 10°C above room temperature, the rate of a reaction doubles. Calculate the activation energy for the reaction.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The units of the rate constant depend on the order of the reaction.

Correct AnswerverifiedShow Answer

In order to obtain the activation energy of a reaction using a graphical method, __________ is plotted against _________, giving a straight line whose slope is equal to __________.

Correct AnswerverifiedShow Answer

A catalyst accelerates a reaction because

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The half-life of a first-order reaction does not depend on the initial concentration of reactant.

Correct AnswerverifiedShow Answer

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L-1s-1, at what rate is [B] changing?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 × 10^-4 mol L^-1 and the rate constant k = 1.08 × 10^-6 s^-1, what concentration of R remains after 25 days?

Correct Answer
verified

Correct Answer
verified

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 10²⁰ molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The active ingredient in an over the counter pain killer analgesic decomposes with a rate constant, k = 9.05 × 10^-4 day^-¹. How many days does it take for 15% of the original ingredient to decompose?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

In order to obtain the activation energy of a reaction using a graphical method, ______ is plotted against _, giving a straight line whose slope is equal to ______.

Correct Answer
verified

Correct Answer
verified

Consider the reaction 2NH₃(g) → N₂(g) + 3H₂(g) If the rate Δ[H₂]/Δt is 0.030 mol L_-1s_-1, then Δ[NH₃ ]/Δt is

Correct Answer
verified

Correct Answer
verified

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L^-1s^-1, at what rate is [B] changing?

Correct Answer
verified