Chapter 10 Example

Example Exam Questions

 

Question 1                           

Figure 1: Data from a differential reactor.

Which of the following best describe the data in the above figure?

  1. Species C could be adsorbed on the surface.

  2. The reaction could be reversible.

  3. Both the above statements could be true.

  4. Neither A or B are on the surface.

  5. None of the above could be true.

Go To Solution #1         









Question 2          

Assume the reaction is irreversible

What can you tell from the above figures?

  1. Species A could be adsorbed on the surface but only very weakly adsorbed.

  2. Species A is not adsorbed on the surface.

  3. Species B is on the surface.

  4. Species A is adsorbed on the surface.

  5. Species C is adsorbed on the surface.

  1. 1 and 2 are true.

  2. 1 and 3 are true.

  3. 1 and 4 are false.

  4. 4 and 5 are true.

  5. 2 and 5 are true.

  Go To Solution #2 









  

 Question 3 

 

            The following data were reported for the reaction

A  B
C D

Which of the following mechanism is consistent with the above data

(a)  (b) (c)
(d) (e)

Go To Solution #3









                                                                                                  

Question

 

The initial rate of reaction is shown below

(a) (b) (c)

         

  1. The reaction is irreversible.

  2. Species B is on the surface.

  3. Species C is on the surface.

  1. 1 and 2 are true.

  2. 1 and 2 are false.

  3. 1 and 3 are false.

  4. 2 and 3 are false.

  5. 2 and 3 are true.

            

Go To Solution #4                                                                                                 









 

Question

  

The initial rate of reaction is shown below

           

1. The rate law is

  Go To Solution #5  










Question 6

For the reaction from Self Tests 12 and 13 we found

which mechanism is consistent with the rate law

   Go To Solution #6  


 







































Solution #1

If the reaction is reversible the increase in PC will decrease the rate. If C is on the surface it will be in the denomination of the rate law and thus increasing PC will decrease the rate.

  Ans: C

Back to Problem #1

Problem #2

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Solution #2

 A is not on the surface or if it is KAPA << 1.  B is on the surface and we see as we increase PB, the rate reaches a plateau. The curves from A, B, and C partial pressure suggest a rate law of the for

Figure 1

Figure 2

Figure 3

Combining

Possible Mechanism

From the rate law we know species B and C are adsorbed on the surface. From the data you canít tell whether or not C is adsorbed on the surface.

 

Ans: E

Back to Problem #2

Problem #3

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Solution #3

Recall

Figure (a) suggests

Figure (b) suggests

Combining

Figure (c) suggests

 

 therefore reaction is irreversible and D is not on surface

  Figure (d) suggests


Combining all the above

Therefore (b) is consistent

Back to Problem #3

Problem 4

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Solution #4

1.   The reaction is irreversible because when PB = 1 atm, increasing the product C does not change the rate. (TRUE)

2.   Species B is on the surface because in 1 we showed that the reaction is irreversible, therefore the only way the rate could decrease were if were in the denominator of the rate law. If a species is in the denominator of the rate law itís on the surface. (TRUE)

3.   Species C is not on the surface because increasing PC does not affect the rate.(FALSE)



Ans: A

Back to Problem #4

Problem #5

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Solution #5

 Low PT

High PT

Combining



Ans: (c)

Back to Problem #5

Problem #6

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Solution #6

    

 

Ans: (e)

Back to Problem #6

Back to Chapter 10