lab 6 - EXPERIMENT 6 SPECTROPHOTOMETRIC DETERMINATION OF A...

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1 EXPERIMENT 6 SPECTROPHOTOMETRIC DETERMINATION OF A TWO-COMPONENT MIXTURE 07F Reference: Harris, Chap 19; Lecture notes; R. E. Kitson, Analyt. Chem. , 22 , 664 (1950). Remarkably few real samples actually contain only one component for any type of analysis. The analysis of pollutants in water requires the determination of many species. The analyses of many alloys require the determination of the concentrations of a few to several metals in the samples. The analyses of many water samples involve the determination of a few to several inorganic components in the solutions. Clinical analyses require the determination of many compounds in a very small sample. It is often possible to determine two components simultaneously using a spectrophotometric technique. The simultaneous determinations are easy if the components being analyzed absorb at different wavelengths and the absorption spectra don't overlap. Simultaneous determination of several elements by atomic emission or atomic absorption spectroscopy is common because the atomic lines are sharp and different wavelengths can be found for the different elements. However, the problem of simultaneous spectrophotometric determination of two components is complicated if the two components absorb in the same spectral region, as is generally the case for the VIS/UV spectra of aqueous solutions. The theory of the analysis is discussed in Harris and in the lecture notes. You will follow procedures similar to those used in Exp. 5. The sample being analyzed in this experiment will be an aqueous solution of Co (II) and Fe (III). Absorption spectra: In Exp. 5 you obtained the absorption spectrum of the Fe 3+ /SCN - complex in an acidic acetone/water mixture and selected the wavelength of maximum absorption (minimum transmission) for analysis. You should follow the same procedure as used in Exp. 5 to determine the absorption
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lab 6 - EXPERIMENT 6 SPECTROPHOTOMETRIC DETERMINATION OF A...

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