Last modified: Fri 01/14/2011 03:51:47 pm
Mechanism ACA

Oklahoma State University

This is ACA # 15. It is OK to use your textbook, but if you can answers the questions without it that is OK too.

Do not press the RETURN or ENTER key while you are answering these questions. Your browser will interpret either the same as clicking on the Submit key.

Answer all of the questions below. If you do not know an answer enter CNA. However, it will help me the most if you answer each question with your best intuition/idea about what would be a reasonable answer.


First Name:

Last Name:

Laboratory Section:

To complete this ACA click on the Reaction link below. When you click on the link a new window will appear. Resize the window and position it on your screen so you can move between it and the ACA window.

1. Once the simulation appears click on the Enable Reactions button and then the Resume button and allow the simulation to run. Describe what you observe happening in the sample region. Use some or all of the following terms in your description: atom, molecule, particle, collision, effective collision, speed, energy, reactant(s), product(s), and intermediate(s).

The Replay option allows you to slow down the motion in the Sample Region and to replay portions of the reaction sequence. You can click on the Pause Button and using the forward or reverse arrows on the time index function, view the motion of the particles a step at a time. You can click the mouse on the Reset button located below the temperature scrollbar to return to the original conditions. To control the number of particles, click Reset, and then use the individual scrollbar to change the amount for a particle.

 

2. Write an overall balanced chemical equation that best describes the reaction you observed in the sample region. (Use the form 2A + B --> A2B when writing the equation. Use a single space to separate a letter from a symbol. Do not worry about trying to represent subscripts.)

3. Assuming a two-step mechanism write each elementary step in the cells below. (Use the form 2A + B --> A2B when writing the equation. Use a single space to separate a letter from a symbol. Do not worry about trying to represent subscripts.)

Step 1:

Step 2:

 

4. Return to the simulation window and click the Reset Button and use the sliderbar to remove all of the R from the sample region. Click on the Enable Reactions button and then the Resume button and observe the interaction in the sample region. Based on your observations propose an alternate mechanism (compared to the mechanism you proposed in Question 3.)

5. Compare and contrast the two mechanisms (Question 3 and Question 4), and indicate similarities and differences you observed.

6. Consider the following possible mechanisms for the following reaction:

2NO2Cl ---> 2NO2 + Cl2

Mechanism I:

Step 1: NO2Cl + NO2Cl ---> 2NO2 + Cl2

 

Mechanism II:

Step 1: NO2Cl ---> NO2 + Cl

Step 2: NO2Cl + Cl ---> NO2 + Cl2

 

Mechanism III:

Step 1: NO2Cl ---> NO2- + Cl+

Step 2: NO2Cl + NO2- ---> 2NO2 + Cl-

Step 3: Cl+ + Cl- ---> Cl2

Select all that could be reasonable mechanisms for the reaction:

a) I only

b) II only

c) III only

d) I and II

e) I and III

f) II and III

g) I, II and III

7. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

8. If there is one question you would like to have answered in lecture, what would that question be?