AP Chem                                                         Unit 12                                     

Chapter 12                                                       Kinetics

Daily

 

 

 

  1. Given the following information, calculate the average rate, Δ[SO2]/Δt , between 10 and 40 minutes for the production of SO2.

 

2SO3(g)à 2SO2(g) + O2(g)

                       

            T/min                   [SO3]/M                    [SO2]/M                      [O2]/M

            

            0.0                          0.124                       0.0                              0.0

            10.0                        0.092                       0.032                          0.01

            20.0                        0.068                       0.056                          0.028

            30.0                        0.050                       0.074                          0.037

            40.0                        0.037                       0.087                          0.044

            50.0                        0.028                       0.096                          0.048

    

            A. 1.8 X 10-3         B.1.5 X 10-3             C. 3.0 X 10-3                   D. 3.2 X 10-3

 

2.Given the following information, calculate the average rate, -Δ[NH3]/Δt, between 10 and 30 minutes for the production of NH3.

 

                                                2NH3(g)à N2(g) + 3H2(g)

 

            T/min                            [NH3]/M                      [N2]/M                         [H2]/M

 

0.0                                                              1.00                             0.0                               0.0

            10.0                             0.083                           0.034                           0.11

            20.0                             0.063                           0.044                           0.024

            30.0                             0.045                           0.053                           0.036

            40.0                             0.033                           0.059                           0.044

            50.0                             0.025                           0.063                           0.049

 

            A. 8.0 X 10-3                B. 1.9 X 10-3                     C. 1.5 X 10-2                     D. 2.3 X 10-3

 

 

  1. For the following reaction, under circumstances where the reverse reaction can be neglected , the reaction rate will depend on which of the options below?

 

A1Cl3(g) + PH3(g)à Cl3A1PH3(g)

 

            A. A1C13                     B. A1C13 and PH3             C. PH3                   D. C13A1PH3

 

 

  1. Based on the following data, determine the rate law of this reaction:

 

SO2(g) + Cl2(g)à SOCl2 + ClO(g)

 

                        Experiment            [SO2](M)               [Cl2](M)                     Initial rate (M/s)

 

                             1                         0.400                     0.400                           0.2918

                             2                         0.400                     0.200                           0.0730

                             3                         0.400                     0.800                           1.1674

                             4                         0.200                     0.800                           0.5837

 

                  A. R= k [SO2]        B. R= k [SO2] [Cl2]        C. R= k [Cl2]         D. R= k [SO2] [Cl2]2

 

 

  1. Based on the following data, determine the overall order of this reaction:

 

2PO(g) + Cl2(g) à 2POCl(g)

            Experiment                   [PO] (M)                     [Cl2] (M)               Initial rate (M/s)

1                                                      0.20                             0.20                      0.40

2                                                      0.20                             0.40                      0.80

3                                                      0.60                             0.20                      3.6

4                                                      0.60                             0.60                      10.8

 

Now what if the data were

 

                   1                           0.2                               0.2                         0.4

                   2                           0.4                               0.2                         3.2

                   3                           0.4                               0.6                         9.6

 

A. 3                             B. 2                              C.5/2                     D. 4

 

  1. In a zero-order rate expression, what units must the specific rate constant possess?

 

A. t/M              B. 1/t                C.M/t               D. 1/M* t

 

  1. A particular drug can be sold until 20% of the original drug has undergone change.     Knowing that k=1.25*10-2/day and the change is first order, how long, in days, will it take before the drug can no longer be sold?

 

A. 17 days       B. 18 days        C. 18 hours      D. 35 hours

 

  1. The decomposition of N20 gas obeys zero-order kinetics. Given a rate constant = 2.46*10-3 M/s and [N2O]120 sec= 0.155M,calculate [N2O]0.

 

A. 0.445          B. 0.450           C. 0.550          D.0.225

 

  1. To determine whether data from different experiments correspond to a zero-order rate expression, a plot of what variables will yield a straight line?

 

A. [X] vs. 1/t                B. [X] vs. t                   C. 1/[X] vs.t                 D. [X]3 vs. 1/t

 

  1. The following is a proposed mechanism for this reaction:

 

H2(g)+Br(g)          2HBr(g)

 

            A. Br2+light        2Br

            B. 2Br+2H2             2HBr+2H

            C. H+Br2              HBr+Br

            D. H+HBr         H2+Br

            E. Br+Br        Br2

 

            In this proposed mechanism, which steps are bimolecular?

            A. a                  B. b,c,d,e                     C. All               D. b,c,d

 

  1. For a reaction to take place, the molecules that are reacting:
    1. Must have more energy than the products
    2. Must have less energy than the products
    3. Must be able to reach the activation energy
    4. Must be in considerable numbers

 

  1. In the following system, give the proper units for k (the rate constant) given R=k[I2]2 and  [I2o]=0.8M , determine the amount of time to reach 75% completion?

 

I2(g) à 2I(g)   k=1.429 X 10-10

                                           UV

 

A. 2.6 X 1010 sec    B. 8.1 X 10-2 sec   C. 3.7 X 106sec    D. 5.56 X109 sec

 

  1. In a “reaction progress” graph, reacting molecules are most unstable at:

 

    1. Their initial position                                           C. Right after they collide
    2. When they are about to collide              D. At the transition state

 

  1. In which of the following examples is a heterogenous catalyst NOT used?

 

    1. Hydrogenation of fats
    2. Oxidation of sulfur dioxide
    3. Decomposition of ozone
    4. Catalytic converters of automobile exhaust systems

 

  1. At 40o C H2O2(aq) will decompose according to the following reaction:

2H2O2(aq)        2H2O(l) + O2(g)

            The following data were collected for concentration of H2O2 at various times.

 

                                    Times(s)                                   [H2O2](M)

0                                                                                                          1.000

2.16 x 104                                       0.500

4.32 x 104                                       0.250

            A. Calculate the average rate of decomposition of H2O2 between 0 and 2.16 x 104s. Use this rate to calculate the rate of production of O2(g).

 

            B. What are these rates for the time period 2.16 x 104s to 4.32 x 104s?

 

 

 

16.Use the given data for the hypothetical reaction: 2A + B à products, to determine the rate law and to evaluate the rate constant at 30˚C.

Reaction #        [A]       [B]       Initial rate (mol/L s)

      1                0.1       0.1                   3 x 10-2

      2                0.1       0.3                   3 x 10-2

      3                0.2       0.3                   6 x 10-2

 

17. Indicate the overall order of reaction for each of the following rate laws.

A.R = k[NO2][F2]

            B.R = k[I]2[H2]

            C.R = k[H2][Cl2]1/2

 

18. The decomposition of H2O2(aq) into H2O(l) and O2(g) is first order. From the data in problem 15, determine the rate constant and the half-life.

 

19. Determine the rate constant (k) and t1/2 for the data pertaining to the decomposition of phosphine (PH3)…hint : use rate expression and table for k.

                                    4PH3(g) à 4P(g) + 6H2

                        Reaction #                    [PH3]               Initial Rate (mol/L s)…not k

                                    1                      0.18                             2.4 x 10-3

                                    2                      0.54                             7.2 x 10-3

                                    3                      1.08                             1.4 x 10-2

 

20. Data for the decomposition of compound AB to give A and B is given below. Determine the rate expression, the rate constant, and t1/2 for a 1 M solution.

                        Reaction #                    [AB]                Initial Rate (mol/L s)…not k

                                    1                      0.2                               3.2 x 10-3

                                    2                      0.4                               12.8 x 10-3

                                    3                      0.6                               28.8 x 10-3

 

21. Using the following information, calculate [NOBr]o if it took 4.31 s for 75% to react (warning do not “double” apply the half life idea as times are not the same for each half life)

                                    2NOBr(g) à 2NO(g) + Br2(g)

            rate = k[NOBr]2, where k = 0.80 L/mol s

 

22. The decomposition of NOCl is a second-order reaction with k = 4.0 x 10-8 L/mol s. Given an initial concentration of 0.50 M, what is the half-life? How much is left after 1 x 108 s? What is the half-life for an initial concentration of 0.25 M?

 

23. The rate law for the reaction:

                        2NO(g) + Cl2(g) à 2NOCl(g)

is R = k[NO]2[Cl]. If an experiment was performed in which the partial pressure of NO(g) initially was 0.1 atm and the initial partial pressure of Cl2(g) was 10 atm, what experimental data would give a straight line plot?

 

24. Write the rate laws for the proposed mechanisms for the decomposition of IBr to I2 and Br2.

            A. IBr(g) à I(g) + Br(g)                                              (fast)

                 IBr(g) + Br(g) à I(g) + Br2(g)                                 (slow)

                 I(g) + I(g) à I2(g)                                                   (fast)

 

            B. IBr(g) à I(g) + Br(g)                                               (slow)

                 I(g) + IBr(g) à I2(g) + Br(g)                                   (fast)

                 Br(g) + Br(g) à Br2(g)                                            (fast)

 

            C. IBr(g)+IBr(g)à I2Br+(g) + Br- (g)                            (fast)

                 I2Br+(g)à Br+(g)+I2(g)                                            (slow)

                 Br-(g) + Br+(g)à Br2(g)                                          (fast)

 

            D. IBr(g) + IBr(g)à I2(g) + Br2(g)                               (one step)

 

25. Write the rate law for the following predicted mechanism for the production of nitrogen dioxide(NO2):

                                                NO+O2ß àNO3       (fast)

                                                NO3+NOà 2NO2      (slow)

 

26. The activation energy for the decomposition HI(g) to H2(g) and I2(g) is 186 kJ/mol. The rate constant at 555 K is 3.52*10-7 L/mols. What is the rate constant at 645 K…hint : use the slope eq and –Ea/R to find the Y value and antiln .

 

27. The rate constant for the reaction:

                                                            C4H8à2C2H4

          At 325o C 6.1* 10-8 s-1. At 525o C the rate constant is 3.16*10-2 s-1. Calculate the activation energy.

 

28.Given the equation below, is the mechanism consistent with the rate expression?

            Equation

                        2NO + 2H2 à 2H2O + N2

            Experimental Rate expression

                        R= k [NO]2[H2]

            Mechanism

                        NO + H2 à N + H2O              S

                        N + NO à N2O                      F

                        N2O + H2 à N2 + H2O           F

           

 

29. Given the following information, verify the order of the reaction with respect to the SO3

                                                2SO3(g)à2SO2(g)+O2(g)

t/min                 [SO3]/M                      

0.0                   0.124                          

10.0                 0.092                          

20.0                 0.068                          

30.0                 0.050                          

40.0                 0.037