Chemical Kinetics

Post-Lab Questions

Answer the following questions using a word processor. Include all relevant data tables and graphs. Use a spreadsheet program to set up tables before pasting into the word processing document. Use the spreadsheet program to find the best-fit line, where applicable. Your lab handout is your guide to performing the calculations correctly. Read it carefully and follow the instructions exactly.

1. Experiments 1 - 7 and Catalyzed Reaction Times incl. Average
2. Initial Concentrations of Reactants and Rates of Reaction
   • Show one sample calculation for finding the rate
3. Order of Each Reactant
   • Show one sample calculation for each reactant
4. Rate Constant for Each Experiment with Average (incl. units)
   • Show one sample calculation
5. Activation Energy Data (incl. rate, rate constant w/units, and ln k)
6. Graph of ln k vs. 1/T showing slope and R² value
   • Show calculation of the activation energy

1. In general, how does the reaction rate depend on the concentrations of the reactants?
2. Why does the reaction rate change as you alter the experimental conditions by changing the initial concentrations?
3. In your own words briefly explain the method you used in this lab to find the differential rate law.
4. Why in this lab did we work on finding the differential rate law and not the integrated rate law?
5. Why is the reaction rate dependent on the temperature at which the reaction takes place?
6. What is the difference between the reaction rate and the rate constant?
7. What was the effect of the catalyst on the measured rate of the reaction? How did the catalyst affect the activation energy of the reaction?
8. What effect does a catalyst have on the rate constant?
9. Comment on the reliability of your data. Were your experiments consistent for a given set of initial conditions? Did the calculated reactant orders of reaction come out close to integers? How well did the activation energy data fit the linear model for the equation ln k = -(E_a/R)·(1/T) + ln A? Give percent errors where possible and comment on why the activation energy data might not have fit the linear model exactly.
10. How could you change the experiments to improve the data? Comment on the virtues or pitfalls of a microscale technique such as that used in this lab.