Chem lab 6 - Jonathan Retta Kristin C. Halfpenny Analysis...

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Jonathan Retta Desk # Kristin C. Halfpenny Thursday 9:35-12:25 Analysis of Cereal Introduction The purpose of this lab was to determine if the actual value of iron in a popular breakfast cereal, Total , and a well known iron tablet were actually accurately advertised. The FDA has called for an investigation on this matter, due to many widespread reports that the iron actually reported were significantly reduced to cutback on costs. Therefore, to determine the actual iron content, the iron will be reduced into a solution, and its absorbance will be measured in a Spectronic machine. The said absorbance will then be converted into the concentration law, and also with a calibration curve. Experiment To determine if the iron content at first, a calibration curve was used to establish its absorbance. One mL of 1.0e-3 M iron nitrate solution was added to a 250 mL beaker, and then the beaker was filled to the 100 mL mark with 0.10 M KCSN solution. Then a clean cuvette was filled with 1.0 M HNO3 , and placed into the spectophotometer. The spectrophotometer was then zeroed to be measuring at the wavelength of 480 nm. After being zeroed, the cuvette was then rinsed out three times with the iron nitrate solution and the absorbance was then measured. After being measured, another 1.0 ml of iron nitrate was added and used to rinse out the cuvette. After several rinses, the absorbance was yet again measured. This same method was used until 10mL of the iron nitrate standard had been added to the KCSN solution. The absorbance rates of the different solutions are as follows:
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1.0e-3 M Iron Nitrate Solution Added (mL) Concentration (M) Absorbance 1 9.9e-6 0.109 2 1.96e-5 0.181 3 2.91e-5 0.249 4 3.85e-5 0.319 5 4.76e-5 0.370 6 5.66e-5 0.421 7 6.54e-5 0.509 8 7.41e-5 0.544 9 8.26e-5 0.599 10 9.90e-5 0.648 The next step was to determine the actual iron levels in the products being investigated. First, 32.0 grams of cereal were weighed out in a 600 mL beaker. Then the cereal was put into a plastic bag and crushed, with only 30.0 grams of the crushed cereal put back into the 600 mL beaker. After this, 250 mL of DI water was added, and a large Teflon magnet was added to the mixture. The mixture was then mixed on a stirring plate for 15 minutes, and after stirred, the magnet was removed from the beaker via tongs. The
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This note was uploaded on 02/11/2009 for the course CHEM 100 taught by Professor Phillips during the Fall '07 term at Vanderbilt.

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Chem lab 6 - Jonathan Retta Kristin C. Halfpenny Analysis...

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