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Chemistry LibreTexts

Kinetics III (Worksheet)

  • Page ID
    79288
  • Name: ______________________________

    Section: _____________________________

    Student ID#:__________________________

    Work in groups on these problems. You should try to answer the questions without referring to your textbook. If you get stuck, try asking another group for help.

    Q1

    Reaction Rates and Rate laws for the following gas phase reaction:

    \[NO(g) + O_3 (g) \rightarrow NO_2(g) + O_2(g)\]

    Given the following data:

    [O3] = 1.0*1014molecules cm-3 [NO] = 2.0*1014 molecules cm-3
    Time [NO] Time [O3]
    0 ms \(6.0 \times 10^8\) 0 1.0 1010
    100 \(5.0 \times 10^8\) 50 8.4*109
    500 \(2.4 \times10^8\) 100 7.0*109
    700 \(1.7 \times10^8\) 200 4.9*109
    1000 \(9.9 \times 10^7\) 300 3.4*109

    Using the data above:

    1. Graph each data set.
    2. Graph ln[] vs. time.
    3. Determine the average rate for the reaction, between each data point.
    4. Use your graph to determine the instantaneous reaction rate at 250 ms.
    5. Given that the reaction is first order in \(NO\) and in \(O_3\), determine the rate constant using your calculated rate for each set of data points
    6. Use the ln[] vs time graph to determine the rate constant.
    7. What is the overall rate law?
    8. Convert the units of the rate constant to moles, liters, and seconds.

    Q2

    Given the following kinetics data for the above reaction:

    T (K) k(L mole-1 sec-1)
    195 1.08 * 109
    230 2.95 * 109
    260 5.42 * 109
    298 12.0 * 109
    369 35.5 * 109
    1. Graph this data as ln(k) vs 1/T.
    2. Determine the activation energy and the preexponential factor from the graph.
    3. What is the rate constant at 150 K?

    Q3

    Catalysis, Temperature, and the Arrhenius equation

    1. For the above reaction mechanism with several additional steps as shown below:

      Step 1: NO + O3 -> NO2 + O2

      Step 2: NO2 + O -> NO + O2

      Overall: O3 + O -> 2 O2

    2. Which species is a catalyst?
    3. Which species is an intermediate?
    4. How does this catalyst effect the rate of the reaction shown below. Ea = 11.9 kJ for the catalyzed reaction and Ea = 14.0 kJ for the uncatalyzed reaction. Calculate the change in the reaction rate at 200, 250, and 300 K
      \[\ce{O_3 + O -> 2 O_2}\]
    5. Draw an energy level diagram for this reaction, with and without catalysis.
    6. For the catalytic destruction of O3 by Cl Ea = 2.1 kJ, Compare the reaction rate for the uncatalyzed reaction and the Cl catalyzed reaction at 250 K.