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Amperometry

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Amperometry
Doug Glosup
CHE 4213.002
03/18/13

Introduction:
Amperometry in chemistry is the detection of ions in a solution based on electric current or changes in electric current. Another words, the measurement of current resulting from the electrochemical reaction at the electrode, is a simple means of determining the concentration of electro-active species. The type of electrochemical cell used in this experiment is a three-electrode cell. The cell consists of working, reference and counter electrodes. The working electrode is the glassy carbon electrode, the reference electrode is that Ag/AgCl reference electrode, and the counter electrode is a platinum wire. The potential is applied between the working in the reference electrodes, and the current measure between the working and counter electrodes. The working electrodes provide the surface for electron transfer to occur for the system under investigation. Experimental:

The working electrode was first polished using 0.3 and 0.5 alumina. A 0.05 M solution with a pH of 7.3 Phosphate buffer solution (PBS), and a 50mM stock solution of Ru(NH3)6Cl3 was made. The PBS buffer was made using NaH2PO4 and NaH2PO4H2O in dilution with 200mL of water. Five different concentrations of Ru(NH3)6Cl3 and one unknown concentration was prepared. The amount needed for each concentration was calculated; 50 µL for 0.25 mM, 100 µL 0.5 mM, 200 µL for one mM, 300 µL for 1.5 mM, 400 µL for for 2mM. The unknown concentration required 80 µL. The electrochemical electrode was set up with three electrodes; the glassy Carbon electrode was the working electrode, Ag/AgCl reference electrode was the reference electrode, and the platinum wire was a counter electrode. Chi832 program with zero voltage, 750 seconds, and 1 e-5 Amp parameters were used to plot an ampoteric IT curve as shown below.

Results:

Conclusion:
One error in prep process of our solutions that did not directly affect our result data was measuring the pH. The...