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Chemistry LibreTexts

Report (Data Analysis and Discussion)

Consult with the lab instructor about content and format of the report. Suggested content includes graphs, plots, calculations and discussion. Make a suggested “do” list with things to consider and questions to answer [see reference 5 about CV calculations].

  1. Show plots of Ip vs. APAP concentration at a scan rate of 100 mV/s, and from the plot calculate and report the concentration of the unknown APAP. Correct the Ip for background charging current by extrapolating the initial straight part at the foot of the wave. With the computer-controlled potentiostat (CS-1200), Ip and Ep values can be determined with the imbedded “math” software, including baseline corrections.
  2. Plot Ip vs. square root of the scan rate for the oxidation of APAP from results obtained at pH 2 and 7.
  3. Are the plots linear? If not, why not?
  4. Does the Ep value for the oxidation of APAP shift with pH? What is the theoretical value of the Ep shift? Show your reasoning.
  5. At pH 7, why is the reverse cathodic peak height less than that for the oxidation of APAP?
  6. At pH 7, what is the formal potential for step 1?
  7. At pH 2, what are the differences in the CVs at slow and fast scan rates? Explain.
  8. Are your results consistent with the proposed mechanism in Figure 1?
  9. Did the results vary with the way in which you pretreated the electrode? What method of pretreatment produced the lowest Epa value and best reproducibility?
  10. Comment on what worked and what did not work for you in this experiment. What changes would you propose to improve the experiment?