CHED 297 |
| A versatile method for evaluation of equilibrium constants from spectrophotometic titrations is described. General algorithms were derived for normalized titration curves of reactions having various stoichiomtric ratios. Direct curve-fitting yielded values for overall equilibrium constants. Evaluation of individual stepwise formation constants was performed, as well as classic point-by-point graphical evaluation was also used to obtain comparative values. The demonstration system chosen for this investigation was the 1:3 complexation reaction of Fe(II) and 1,10-phenantroline (o-Phen). Resulting curves revealed reproducible initial deviation when titrating Fe(II) with o-Phen. Evaluation of these curves accounted for intermediate species and provided the means for assessment of both stepwise and overall equilibrium constants. No unusual deviations were evident anywhere in the titration curves when Fe(II) was the titrant. Our consistent results demonstrate the versatility of combining spectrophotometric titrations, algorithms, and curve-fitting software for the determination of equilibrium constants and elucidation of stepwise reactions. |
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Undergraduate Research Poster Session: Analytical Chemistry
11:00 AM-1:00 PM, Monday, March 26, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Chemical Education |