Kinetics Exercise
This problem set was developed by S.E. Van Bramer for Chemistry 146 at Widener University.
For the reaction 2 NO2 <-> 2 NO + O2 At 300 C
Kinetics Data
| Experimental Data from Zumdahl |
| time (s) | NO2 (atm) | NO (atm) | O2 (atm) |
| 0 | 0.0100 | 0 | 0 |
| 50 | 0.0079 | 0.0021 | 0.0011 |
| 100 | 0.0065 | 0.0035 | 0.0018 |
| 150 | 0.0055 | 0.0045 | 0.0023 |
| 200 | 0.0048 | 0.0052 | 0.0026 |
| 250 | 0.0043 | 0.0057 | 0.0029 |
| 300 | 0.0038 | 0.0062 | 0.0031 |
| 350 | 0.0034 | 0.0066 | 0.0033 |
| 400 | 0.0031 | 0.0069 | 0.0035 |
- Plot NO2 pressure vs time
- Plot NO pressure vs time
- Plot O2 pressure vs time
Rate of the reaction:
Calculate the average concentration and the average rate of the reaction for each of the time differences. What are the appropriate units for the rate of the reaction?
- 0-50 s
- 50-100 s
- 100-150 s
- 150-200 s
- 200-250 s
- 250-300 s
- 300-350 s
- 350-400 s
Graph the rate of the reaction for each time increment.
Rate Constant
The rate equation for a chemical reaction follows the form: Rate = k[reactant]x where:
- Rate is the rate of the reaction
- k is the rate constant for the reaction
- [reactant] is the concentration of the reactant
- x is the order of the reaction
- For the reaction of NO2, assume the reaction is zero order and calculate the rate constant k at each time interval and plot the results below. What are the units for k if the reaction is zero order? Comment on how well this assumption works.
- For the reaction of NO2, assume the reaction is first order and calculate the rate constant k at each time interval. What are the units for k if the reaction is zero order? Comment on how well this assumption works.
- For the reaction of NO2, assume the reaction is second order and calculate the rate constant k at each time interval. What are the units for k if the reaction is second order? Comment on how well this assumption works.
- Based upon the figures above, which of the following equations best fits this experimental data.
- rate = k [NO2]0
- rate = k [NO2]1
- rate = k [NO2]2
Rate Equation
Determine the rate equation for this reaction. Include the order of the reaction and the rate constant.
Graphs and figures to accompany exercise discussion
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Scott Van Bramer
Department of Chemistry
Widener University
Chester, PA 19013
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Last Updated 1/16/2008