Oxalate Lab Essay

609 Words3 Pages
Dr. Hjorth-Gustin

Chemistry 201 Lab

November 8th, 2010

Synthesis and Analysis of Iron(III) Oxalate Complex Discussion

This experiment initially involved the synthesis of an iron (III) oxalate complex with the general formula Kw[Fex(C2O4)y] zH2O. The variables x, y, and z were determined

through the duration of the entire experiment. Part 1 involves the synthesis of an iron (III) oxalate complex. The iron is first presented in its Fe2+ form, so it must first be oxidized to

Fe3+ before the oxalate ion will readily bind to it. Hydrogen peroxide is the oxidant of choice: 2Fe2+ (aq) + H2O2 (l) + 2H+ (aq) ---> 2Fe3+ (aq) + 2H2O (l), in acidic solution.

The oxalate ion is then free to coordinate to the Fe3+ ion, forming a
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Part 2 of this experiment invoked the use of redox

titrating to determine the oxalate content (C2O42-) of the salt. An aqueous solution of the iron oxalate salt is prepared for titration, and the oxalate content is found through analysis

by measuring the volume of titrant.

Part 3 of the experiment utilized Spectrophotometry to determine the iron content in the iron (III) oxalate complex. The results were combined with findings from Part 1 and

Part 2 to determine the empirical formula and percentage yield of the compound synthesized in Part 1. Spectrophotometry is a routine laboratory test that has the added advantage

of being able to analyze multiple samples in a short amount of time. The most efficient way of determining concentration is to prepare a set of standard solutions of known

concentration, record the absorbance readings at a fixed wavelength, and plot the absorbance vs. concentration data. The wavelength of 520 nm was selected for experiment Part

3 because this is the maximum absorbance for the iron (III) ion. The Beer's Law Plot that was graphed came out to be linear with an equation of:

Absorbance = 5.395 x 10^3(Fe^+2-Bipy) - 0.0014.

The empirical formula that was determined was different from that of the “true” compound mentioned. The empirical formula determined was:

K3[Fe(C2O4^-2)3] 3 H2O

If had there been a better alternate method to determining the iron
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