Supporting Information Placeholder: Feerricyanide Diffusion Barrier

Supporting Information Placeholder

ABSTRACT: In this experiment, the ferricyanide diffusion coefficient was determined using chronoamperometry and cyclic voltammetry. The diffusion coefficient was 2.25 x 10-6 cm2/s for chronoamperometry and 1.62 x 10-6 cm2/s for cyclic voltammetry. Cyclic voltammetry was also used to identify three unknown compounds. Unknown A, B and C was determined to be benzoquinone, thyronine and tyrosine, respectively.

Introduction:

Electrochemistry is one of the most widespread branches in chemistry. Electrochemistry is the study of reactions that generate electricity through the transfer of electrons. Its applications are seen in everyday life from the use of cell phones, laptops, cars, batteries, and fuel cells.

The main forms of voltammetry are polarography, stripping, and cyclic voltammetry. Polarography uses a dropping-mercury working electrode, which can be used with a staircase or square wave potential technique. Staircase voltammetry applies a potential, holds for a second at the potential and then increases to a higher potential, holding for a second. This is repeated for multiple potential giving a voltammogram that looks like a staircase. This allows an accurate measurement of the faradaic current, which is the current of the redox reaction of the analyte at the electrode, by minimizing the charging current, which is the flow of ions in solution towards the electrode. Square wave voltammetry works in a similar manner. The potential is held constant for one second, decreased to a lower potential, holds for a second, then increases potential to a potential higher than first potential, holds for a second, then drops to a lower potential higher than the second potential. This method allows fast analysis time. Stripping voltammetry involves precipitating the analyte on the working electrode. The potential of the cell is then changed so the analyte is removed from the electrode. By monitoring the change in current with respect to potential, stripping voltammetry provides a sensitive and accurate quantitative analysis of the analyte concentration. Cyclic voltammetry uses both positive and negative potential scanning rates to detect both oxidation and reduction reaction potentials. This allows the observation of electrochemical behavior of the analyte generated at the