Last modified: Sun 01/17/2016 03:21:08 pm
BCE

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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.

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The following data was collected for the first order reaction described in the reaction

A ---> Products

 

[A] (M)

Time (seconds)

0.4880

0

0.4665

10

0.4361

25

0.3897

50

0.3482

75

0.3112

100

0.2781

125

0.2440

154

0.1984

200

0.1416

275

0.1220

308

0.1010

350

0.0610

462

0.0411

550

0.0305

616

0.0209

700

0.0133

800

0.0054

1000

In chemical kinetics the half-life for a chemical reaction is defined as the time required for the initial concentration to fall to one half its value.

1. In the data above what is the initial concentration for the reactant A?

[A]o = M

2. How long does it take for the initial concentration to fall to half of its initial value?

seconds

3. What is the concentration of A at the first half-life?

M

4. What is the concentration of A at the second half-life?

M

5. What is the concentration of A at the third half-life?

M

6. What is the concentration of A at the sixth half-life?

M

7. How long does it take [A] to fall from 50% of its initial concentration to 25% of its initial concentration (2nd half-life)?

seconds

8. What is interesting about the half-life data for this first order reaction?

9. Below are two figures with associated times, what is the half-life of the reaction?

minutes

10. Which of the following figures represents the system shown in Q9 after two half-lives?

(Enter choice A, B, C or D)

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

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