Quant Analysis Lab 7 - Sean Murphy Group 3 Dr Wei...

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Sean Murphy Group 3 Dr. Wei Determination of Fe by UV-Vis Spectrometry Introduction: A complex of iron (II) is formed with 1,10-phenanthroline, Fe(C12H8N2)3 2+ , and the absorbance of this colored solution is measured with a spectrophotometer. The spectrum is plotted to determine the absorption maximum. Hydroxylamine (as hydrochloride salt to increase solubility) is added to reduce Fe3+ to Fe2+ and to maintain it in that state. 4 Fe3+ + 2NH2OH → 4Fe2+ + N2O + 4H+ + H2O Materials: 1, 10-Phenanthroline solution Standard iron (II) stock solution Hydroxylammonium chloride solution Sodium acetate solution Unknown: 12mL for each group Volumetric Flasks 5, 10, and 25mL volumetric pipets Procedure: 1. Into each of the five 100mL volumetric flasks, pipet 5, 10, 15, 20, and 25 mL of the standard iron (II) stock solution into the flasks. 2. Pour 50mL of DI-water into a 6 th flask to serve as the “blank”. 3. Obtain 12mL of the unknown sample, place in a 7 th flask and treat it in the same manner as the standards.

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