Chem106C13: Chapter 13 End-of-Chapter Problems Collection

1. Define Reaction Rate

2. TRUE or FALSE: Changes in the temperature or the introduction of a catalyst will affect the rate constant of a reaction

For sample problems 3-6, use Formula 1 to answer the questions

H2O?2H2+O2(1)*Assume the reaction occurs at constant temperature

3. For the given reaction above, state the rate law.

4. State the overall order of the reaction.

5. Find the rate, given k = 1.14 x 10^-2 and [H₂O] = 2.04M

6. Find the half-life of the reaction.

7. Define Reaction Order

Use the following information to solve questions 8 and 9:

Given the rate law equation: Rate = k[A]¹[B]²

8 a) Determine the reaction order with respect to A, b) the reaction order with respect to B, and c) the total reaction order for the equation.

Use the data table below to answer questions 9 and 10

 

Experiment	[A] M	[B] M	Rate M Min-1
1	0.100	0.100	1.0 x 10-3
2	0.400	0.100	2.0 X 10-3
3	0.100	0.150	2.0 x 10-3

 

9.  Use The Differential Method to determine the reaction order with respect to A (x) and B (y). What is the total reaction order (n)?

10. What is the rate constant k?

11. Using the integrated form of the rate law, determine the rate constant k of a zero-order reaction if the initial concentration of substance A is 1.5 M and after 120 seconds the concentration of substance A is 0.75 M.

12. Using the substance from the previous problem, what is the half-life of substance A if its original concentration is 1.2 M?

13. Given the following information, determine the order of the reaction and the value of k, the reaction constant.
Concentration (M)         Time (s)
1.0                                 10
.50                                 20
.33                                 30

*Hint: Begin by graphing

14. The reaction between nitric oxide and oxygen:

2NO + O ₂ ? 2NO ₂

is found experimentally to obey the rate law

Rate = k( c _NO) ²( c _O2)

Decide which of the following mechanisms is compatible with this rate law:

   a) NO + NO ? N₂O₂           fast

         N₂O₂ + O₂ ? 2NO₂         slow

   b)  NO + NO ? NO₂ + N     slow

         N + O₂ ? NO₂             fast

   c)  NO + O₂ ? NO₃            fast

         NO₃ + NO ? 2NO₂         slow

   d)   NO + O₂ ? NO₂ + O      slow

         NO + O ? NO₂             fast 

15. Suppose the activation energy of a certain reaction is 250 kJ/mol. If the rate constant at T1 = 300 K is k1, and the rate constant at T2 = 320 K is k2, then k2/k1 = _______. (The       universal gas constant = 8.314 J/mol•K.)

             (a) 3 x 10–29    (b) 0.067          (c) 15.0            (d) 525                        (e) 3 x 1028

16. The reaction, A  +  2B    ->    B2  +  A, proceeds by the following mechanism: (A is a catalyst.)

                        A   +   B     ->     AB                                      (slow)

                        AB   +   B     ->     B2   +   A                          (fast)

            What is the rate law expression for this reaction?

17. The rate-law expression for the following reaction is found to be rate = k[N₂O₅]. What is the overall reaction order? 

    2N₂O₅(g) -> 4NO₂(g) + O₂(g)

18. Given these data for the following reaction:

(C₂H₅)₂(NH₂) + I₂ -> (C₂H₅)₂N₂ + 2HI

Expt.	[(C2H5)2(NH2)]0 (mol/L)	[I2]0 (mol/L)	Initial Rate of Formation of  (C­2H5)2N2
1	0.015	0.015	3.15 M/s
2	0.015	0.045	9.45 M/s
3	0.030	0.045	18.9 M/s

a)      a) Write the rate-law expression.

b)      b) What is the value, with units, for the specific rate constant?

19. a) Using the following information, determine the half life of this reaction, assuming there is a single reactant.
Concentration (M)        Time (s)
2.0                                 0
1.3                                10
.9633                            20
b) Given the information from the previous problem, what is the concentration after 5 minutes?

20. The second-order rate constant for the following gas phase reaction is 0.0442 M^-1s^-1. We start with 0.135 mol C₂F₄ in a 2.00 L container with no product initially present. 

a) What will the concentration of C₂F₄ after 1.00 hour?

c)What is the half-life of the reaction from the initial C₂F₄ concentration given in part (a)?

d)How long will it take for half of the C₂F­₄ that remains after 1.00 hour to disappear?

21. The rate constant for a first-order reaction is 0.58 s^–1 at 25 ^oC.  At what temperature would the rate constant have a value of 0.75 s^–1?  The activation energy is 84 kJ/mol and the universal gas constant = 8.314 J/mol•K. (Hint: use the following manipulation of the Arrhenius equation

Answers to Ch 13 Problems