Experiment 4-Spectrophotometric Determination of Iron in Vitamins

# Experiment 4-Spectrophotometric Determination of Iron in Vitamins

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Laboratory Report Form for Chem 207L Expt. 4 – Spectrophotometric Determination of Iron in Vitamins Analytical Chemistry Laboratory – Fall 2010 Name: Krista Hawley Kelley Krueger Brittany Adams Date(s): 11/3/10 and 11/10/10 Total Points Possible – 100 pts . Objectives: (5 points) 1. Introduce and familiarize the student with Beer’s Law. 2. Record the absorption curve for the compound, [Fe(o-phenanthroline) 3 ] 2+ , in the visible range (400 to 800 nm) 3. Prepare a calibration curve (ppm Fe vs. absorbance) for solutions of [Fe(o- phenanthroline) 3 ] 2+ @ 508 nm 4. Determine the molar absorptivity coefficient for [Fe(o-phenanthroline) 3 ] 2+ @ 508 nm 5. Determine the amount of iron in each pill, capsule, or liquid dose of a commercial vitamin containing iron Background: (13 points) In the space below write the equation which describes Beer;s Law. Define each term in this equation and specify the units for each term making sure they are consistent with each other. (9 points) A= BC A= No Units Absorbance = M -1 cm -1 molar asorptivity C = M Molarity B = cm Width of cuvette

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Below draw the structure of the orange iron complex whose absorbance was measured during this experiment. You can use the symbol “N------N” in lieu of the organic ligand if you wish in drawing this structure. Make sure you show the proper charge on the overall complex. Below the structure state the oxidation number of the iron in this complex and state the wavelength at which this complex has its maximum absorbance. (4 points) Two Key Chemical Equations: (4 points) Make sure each equation is balanced paying particular attention the hydrogen atoms. 2 Fe
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Experiment 4-Spectrophotometric Determination of Iron in Vitamins

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