Optional Experiment
- Page ID
- 60997
In strong acid (e.g., 1 to 2 M sulfuric acid) the rate of step 4 becomes sufficiently fast that the reduction of benzoquinone, species V, can be observed on the reverse cathodic scan. If you continue to run successive CV scans, the build-up of benzoquinone and its reduced form, hydroquinone, can be observed by the appearance of a wave just prior to the wave for APAP. The scan rate provides the “time window” for observation of different species in the mechanism.
Run CV of 2.0 mM APAP in 1 M sulfuric acid at scan rate of 20, 50, 100 and 200 mV/s. The potential range for the scan is -200 mV to 1000 mV, and then back to –200 mv. Run 10 continuous CV cycles at a scan rate of 100 mV/s to observe the appearance of waves due to benzoquinone/hydroquinone couple.
The kinetic rate for step 4 \(\rightarrow\) 5, the formation of benzoquinone, is determined by using the method described in reference 7. Discuss the method and results of your kinetic analysis in your Report.