Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.

Lesson: Multi-Step Reaction Kinetics

Worksheet • 8 Questions

Q1:

Compound D is produced with an overall rate constant π‘˜ . The reaction involves three elementary reactions:

Write a balanced chemical equation for the overall reaction.

  • A B + E 2 D
  • B A + B + E 2 D
  • C A + E D
  • D A + B D
  • E E 2 D

Which species act as catalysts in this reaction?

  • A A only
  • B C only
  • C B only
  • D A and C
  • E A and B

Use the preequilibrium approximation to find an expression for π‘˜ in terms of the elementary reaction rate constants.

  • A π‘˜ π‘˜ π‘˜    
  • B π‘˜ π‘˜ π‘˜    
  • C π‘˜ βˆ’ π‘˜ π‘˜    
  • D π‘˜ ( π‘˜ βˆ’ π‘˜ )    
  • E π‘˜ ( π‘˜ βˆ’ π‘˜ )    

In the preequilibrium approximation, what is the rate law for the overall reaction?

  • ARate = π‘˜ [ ] [ ] [ ] [ ] A B E D
  • BRate = π‘˜ [ ] [ ] [ ] [ ] A D E B
  • CRate = π‘˜ [ ] [ ] [ ] [ ] A B D E
  • DRate = π‘˜ [ A ] [ E ]
  • ERate = π‘˜ [ B ] [ E ]

Q2:

Compound A decomposes into compounds C, D and E. The decomposition involves three elementary reactions:

  • Reaction 1: A B , rate constant = π‘˜  .
  • Reaction 2: A + B B + C + D , rate constant = π‘˜  .
  • Reaction 3: 2 B E , rate constant = π‘˜  .

The rates of reaction may be estimated by using a steady-state approximation. In this approximation, the rate of change of [B] is zero.

The stoichiometry of the reaction depends on the relative rates of reactions 2 and 3. Based on the mechanism described, which of the following is not a balanced reaction equation?

  • A 8 A 3 C + 3 D + 4 E
  • B 7 A C + D + 3 E
  • C 4 A 2 C + 2 D + E
  • D 1 3 A 5 C + 5 D + 4 E
  • E 1 0 A 4 C + 4 D + 3 E

Which condition must be satisfied for the steady-state approximation to be valid?

  • A π‘˜ ≫ π‘˜  
  • B π‘˜ β‰ͺ π‘˜  
  • C π‘˜ β‰ͺ π‘˜  
  • D π‘˜ ≫ π‘˜  
  • E π‘˜ ≫ π‘˜  

Use the steady-state approximation to find an expression for the rate of formation of C in terms of [A] and the elementary reaction rate constants.

  • A d C d A [ ] 𝑑 = π‘˜ ο„Ÿ π‘˜ π‘˜ [ ]     
  • B d C d A [ ] 𝑑 = π‘˜ ο„Ÿ π‘˜ π‘˜ [ ]     
  • C d C d A [ ] 𝑑 = π‘˜ ο„Ÿ π‘˜ π‘˜ [ ]   
  • D d C d A [ ] 𝑑 = π‘˜ ο„Ÿ π‘˜ π‘˜ [ ]   
  • E d C d A [ ] 𝑑 = π‘˜ ο„Ÿ π‘˜ π‘˜ [ ]     

Use the steady-state approximation to find an expression for the rate of formation of E in terms of [A] and the elementary reaction rate constants.

  • A d E d A [ ] 𝑑 = π‘˜ [ ] 
  • B d E d A [ ] 𝑑 = π‘˜ [ ]  
  • C d E d A [ ] 𝑑 = π‘˜ [ ]  
  • D d E d A [ ] 𝑑 = π‘˜ π‘˜ π‘˜ [ ]   
  • E d E d A [ ] 𝑑 = π‘˜ π‘˜ π‘˜ [ ]   

Q3:

A reaction proceeds via three elementary reactions:

  • Reaction 1: A + B C , rate constant = π‘˜ 1 .
  • Reaction 2: C A + B , rate constant = π‘˜ βˆ’ 1 .
  • Reaction 3: C D + E , rate constant = π‘˜ 2 .

In the steady-state approximation, the rate of change in [C] is equal to zero.

Write a balanced chemical equation for the overall reaction.

  • A A + B D + E
  • B B D + E
  • C A D + E
  • D A + C D + E
  • E C D + E

Find an expression for [C] in terms of [A], [B] and the elementary reaction rate constants.

  • A π‘˜ π‘˜ + π‘˜ [ ] [ ] 1 βˆ’ 1 2 A B
  • B π‘˜ π‘˜ + π‘˜ ( [ ] + [ ] ) 2 βˆ’ 1 2 A B
  • C π‘˜ π‘˜ [ ] [ ] 1 βˆ’ 1 A B
  • D π‘˜ π‘˜ βˆ’ π‘˜ [ ] [ ] 1 βˆ’ 1 2 A B
  • E π‘˜ π‘˜ ( [ ] + [ ] ) 2 βˆ’ 1 A B

Which condition must be satisfied for the reaction to follow Michaelis-Menten kinetics?

  • A B D =
  • B A B D E = = =
  • C B D E = =
  • D A B =
  • E D E =

Q4:

Nitryl chloride ( N O C l ) 2 decomposes with an overall rate constant π‘˜ . The decomposition involves five elementary reactions: Reaction 5 is the rate-determining step. The reaction may be modeled using two preequilibrium approximations:

  • rate of reaction 1 = rate of reaction 2,
  • rate of reaction 3 = rate of reaction 4.

Write a balanced chemical equation for the overall reaction.

  • A 2 N O C l 2 N O + C l 2 2 2
  • B 6 N O C l N O + 2 N O + 4 C l O + C l 2 2 2 2 2
  • C 1 6 N O C l 8 N O + 8 N O + 6 C l O + 5 C l 2 2 2 2 2
  • D 8 N O C l 4 N O + 6 C l O + C l 2 2 2 2
  • E 3 N O C l N O + N O + C l O + C l 2 2 2 2 2

Use the preequilibrium approximation to find an expression for π‘˜ in terms of the elementary reaction rate constants.

  • A π‘˜ π‘˜ π‘˜ π‘˜ π‘˜ 1 2 3 βˆ’ 1 βˆ’ 2
  • B π‘˜ + π‘˜ π‘˜ + π‘˜ π‘˜ 1 2 βˆ’ 1 βˆ’ 2 3
  • C π‘˜ ( π‘˜ βˆ’ π‘˜ ) ( π‘˜ βˆ’ π‘˜ ) 3 1 βˆ’ 1 2 βˆ’ 2
  • D π‘˜ βˆ’ π‘˜ π‘˜ βˆ’ π‘˜ π‘˜ 1 βˆ’ 1 2 βˆ’ 2 3
  • E π‘˜ + π‘˜ + π‘˜ π‘˜ + π‘˜ 1 2 3 βˆ’ 1 βˆ’ 2

In the preequilibrium approximation, what is the rate law for the overall reaction?

  • ARate = π‘˜ [ ] [ ] N O C l N O 2 2 2
  • BRate = π‘˜ [ ] [ ] N O C l C l 2 2
  • CRate = π‘˜ [ ] [ ] N O C l N O 2 2
  • DRate = π‘˜ [ ] [ ] [ ] N O C l N O C l 2 2 2 2
  • ERate = π‘˜ [ ] [ ] N O C l C l 2 2 2

Q5:

A reaction proceeds via four elementary reactions with an overall rate constant π‘˜ :

  • Reaction 1: 2 A B , rate constant = π‘˜ 1 .
  • Reaction 2: B 2 A , rate constant = π‘˜ βˆ’ 1 .
  • Reaction 3: B + C D + E , rate constant = π‘˜ 2 .
  • Reaction 4: C + E D + F , rate constant = π‘˜ 3 .

Write a balanced chemical equation for the overall reaction.

  • A 2 A + 2 C 2 D + F
  • B A + 2 C 2 D + 2 F
  • C A + C D + F
  • D 2 A + C D + 2 F
  • E 2 A + C 2 D + F

The reaction is found to be second-order with respect to A and first-order with respect to C. Identify the rate-determining step for the reaction.

  • AReaction 3
  • BNo single step is rate-determining.
  • CReaction 1
  • DReaction 4
  • EReaction 2

Use the pre-equilibrium approximation to find an expression for π‘˜ in terms of [A], [C] and the elementary reaction rate constants.

  • A 2 π‘˜ π‘˜ π‘˜ 1 2 βˆ’ 1
  • B π‘˜ π‘˜ 2 βˆ’ 1
  • C π‘˜ π‘˜ π‘˜ 1 2 βˆ’ 1
  • D 2 π‘˜ π‘˜ 2 βˆ’ 1
  • E π‘˜ π‘˜ 2 π‘˜ 1 2 βˆ’ 1

Q6:

The decomposition of compound A proceeds via three elementary reactions:

  • Reaction 1: A B , rate constant = π‘˜  .
  • Reaction 2: B A , rate constant = π‘˜   .
  • Reaction 3: B C + D , rate constant = π‘˜  .

Which condition must be satisfied for the pre-equilibrium approximation to be valid?

  • A π‘˜ ≫ π‘˜   
  • B π‘˜ β‰ˆ π‘˜   
  • C π‘˜ β‰ͺ π‘˜  
  • D π‘˜ ≫ π‘˜   
  • E π‘˜ β‰ˆ π‘˜   

Under which of the following conditions would the steady-state approximation be valid but not the pre-equilibrium approximation?

  • A π‘˜ > π‘˜ ≫ π‘˜    
  • B π‘˜ β‰ˆ π‘˜ ≫ π‘˜    
  • C π‘˜ > π‘˜ ≫ π‘˜    
  • D π‘˜ ≫ π‘˜ β‰ˆ π‘˜    
  • E π‘˜ ≫ π‘˜ ≫ π‘˜    

In the steady-state approximation, the rate of change of [B] is zero. What is the rate of change of [B] in the pre-equilibrium approximation, in terms of [A] and the elementary reaction rate constants?

  • A βˆ’ π‘˜ π‘˜ π‘˜ [ ]     A
  • B βˆ’ ( π‘˜ + π‘˜ ) [ ]    A
  • C ( π‘˜ βˆ’ π‘˜ βˆ’ π‘˜ ) [ ]     A
  • D βˆ’ π‘˜ π‘˜ π‘˜ [ ]     A
  • E βˆ’ π‘˜ [ ]  A

Q7:

The decomposition of compound A into compounds B and E is a first-order reaction with overall rate constant π‘˜ . The decomposition involves four elementary reactions:

  • Reaction 1: A B + C , rate constant = π‘˜  .
  • Reaction 2: B + C A , rate constant = π‘˜   .
  • Reaction 3: B + C B + D + E , rate constant = π‘˜  .
  • Reaction 4: C + D 2 B , rate constant = π‘˜  .

The rate law for this reaction is given by:

Write a balanced chemical equation for the overall reaction.

  • A 2 A 4 B + E
  • B A 4 B + E
  • C A 2 B + E
  • D 2 A B + E
  • E 2 A 2 B + E

In the pre-equilibrium approximation, the rates of reactions 1 and 2 are equal. Use the pre-equilibrium approximation to find an expression for π‘˜ in terms of the elementary reaction rate constants.

  • A π‘˜ π‘˜ π‘˜    
  • B π‘˜ ( π‘˜ + π‘˜ ) π‘˜     
  • C π‘˜ ( π‘˜ + π‘˜ ) π‘˜     
  • D π‘˜ π‘˜ π‘˜    
  • E ( π‘˜ + π‘˜ ) π‘˜    

In the steady-state approximation, the rates of change of [C] and [D] are zero. No assumptions are made regarding [B] or the rates of reactions 1 and 2. Use the steady-state approximation to find an expression for π‘˜ in terms of the elementary reaction rate constants.

  • A π‘˜ π‘˜ π‘˜ + 2 π‘˜     
  • B π‘˜ π‘˜ π‘˜ βˆ’ π‘˜ βˆ’ π‘˜      
  • C π‘˜ π‘˜ π‘˜ βˆ’ π‘˜     
  • D π‘˜ π‘˜ π‘˜ + π‘˜ + π‘˜      
  • E π‘˜ π‘˜ π‘˜ + π‘˜     

Which condition must be satisfied for the pre-equilibrium and steady-state approximations to produce the same expression for π‘˜ ?

  • A π‘˜ ≫ π‘˜   
  • B π‘˜ π‘˜ β‰ͺ π‘˜ + π‘˜ + π‘˜      
  • C π‘˜ ≫ π‘˜ + π‘˜    
  • D π‘˜ β‰ͺ π‘˜   
  • E π‘˜ π‘˜ ≫ π‘˜ βˆ’ π‘˜ βˆ’ π‘˜      

Q8:

Compounds A and C react to form compound D with an overall rate constant π‘˜ . The reaction involves three elementary reactions:

Write a balanced chemical equation for the overall reaction.

  • A A + 2 C 2 D
  • B A + 2 C D
  • C A + C D
  • D 2 A + C 2 D
  • E 2 A + 2 C D

Which condition must be satisfied for the preequilibrium approximation to be valid?

  • A π‘˜ ≫ π‘˜ βˆ’ 1 2
  • B π‘˜ β‰ˆ π‘˜ 1 βˆ’ 1
  • C π‘˜ β‰ͺ π‘˜ βˆ’ 1 2
  • D π‘˜ ≫ π‘˜ βˆ’ 1 1
  • E π‘˜ β‰ˆ π‘˜ + π‘˜ 1 βˆ’ 1 2

In the preequilibrium approximation, the rates of reactions 1 and 2 are equal. Use the preequilibrium approximation to find an expression for π‘˜ in terms of the elementary reaction rate constants.

  • A π‘˜ ο„Ÿ π‘˜ π‘˜ 2 1 βˆ’ 1
  • B π‘˜ ο„Ÿ π‘˜ π‘˜ 2 βˆ’ 1 1
  • C ο„Ÿ π‘˜ π‘˜ βˆ’ 1 1
  • D π‘˜ ο„Ÿ π‘˜ π‘˜ 1 βˆ’ 1 2
  • E π‘˜ ο„Ÿ π‘˜ π‘˜ 1 2 βˆ’ 1

In the preequilibrium approximation, what is the order of reaction with respect to A ?

  • A 1 2
  • B 0
  • C 1
  • D 2
  • E 3 2
Preview