Posted by Suzy on Sunday, November 18, 2007 at 2:56pm.
The starting materials for this lab were: a crucible, breakfast cereal (Kix), bun cent burner, 100 mL beaker, hot plate, 100 mL volumetric flask and stopper, a funnel and filter paper. First off by taking the breakfast cereal crushed up and placing it into the crucible, letting it burn into black ash, the cereal was then transferred into the 100 mL beaker with hydrochloric acid and brought to a boil.
Obtaining a 100 mL flask, it was place under the funnel and the liquid of cereal and hydrochloric acid was filtered out into the flask and a stopper was put on the top.
The 100 mL volumetric flask with the colorless iron solution was fitted with a rubber stopper. First, transfer the colorless iron solution into a 250 mL volumetric flask, since the substance in the 100 mL volumetric flask was too much.
The 250 mL volumetric flask was filled with 10 mL of sodium acetate by a graduated cylinder, 1 mL of hydroxylamine hydrochloride by a micro liter pipette and 10 mL phenanthroline by a graduated cylinder. Then the volumetric flask was not to the mark so, the next step was to dilute the solution and fill it with distilled water and shake it up to mix the iron phenanthroline solution up.
Five volumetric flasks labeled 100-500 mL were filled with sodium acetate, hydroxylamine hydrochloride, and phenanthroline and distilled water and filled to the mark on the volumetric flask. These solutions were placed one after another into the cuvet to test the wavelength and get the highest point of absorbance.
After testing the five solutions in the volumetic flasks, the next step was to take the iron phenanthroline solution in the volumetric flask when it was ready to be inserted into an Ocean Optics USB2000+ Miniature Fiber Optic Spectrometer.
First the cuvet had to be filled with distilled water and was placed into the spectrometer and set closest to zero, the spectrometer was set for about .077, and then the volumetric flask with the solution of iron-phenanthroline was tested in the cuvet at 510.3 nm for the wavelength of maximum absorbance.
The starting materials for this lab were: a crucible(what size, breakfast cereal (Kix)how much, bun cent Bunsen burner, 100 mL beaker, hot plate, 100 mL volumetric flask and stopper, a funnel and filter paper. (I would add the solutions and chemicals (with concentrations) here since you used them in the experiment, too. Also I don't see the spectrometer listed.)
I would make a separation between the materials used and the procedure. First off by taking the breakfast cereal crushed up and placing it into the crucible, letting it burn into black ash, the cereal was then transferred into the 100 mL beaker with hydrochloric acid and brought to a boil. The breakfast cereal (how much?) was crushed, placed in a crucible, and the crucible was placed in a furnace at ??? degrees C. The sample was heated until all of the contents were carbonized (about how long?). The sample was transferred to a 100 mL beaker, hydrochloric acid (what strength) was added to the contents of the beaker and the solution was boiled (how long?), then filtered into a 100 mL volumetric flask using (what kind) of filter paper. The transfer step, where you removed the carbonized ash from the crucible, placed it in a beaker, then added HCl and filtered, probably is the major source of your error. You probably tried to remove all of the iron and the black residue from the heated crucible but SOME of the iron probably was left in the crucible. You can cite this at the end when you talk about how and why the results might be low
Obtaining a 100 mL flask, it was place under the funnel and the liquid of cereal and hydrochloric acid was filtered out into the flask and a stopper was put on the top.
The 100 mL volumetric flask with the colorless iron solution was fitted with a rubber stopper. First, transfer the colorless iron solution into a 250 mL volumetric flask, since the substance in the 100 mL volumetric flask was too much. I don't get this part. What was too much (what substance) and why did you make the transfer from the 100 mL volumetric flask to the 250 mL volumetric flask. I will leave this part for you to fix. If the volume of the liquid plus what you would need to add; i.e., the sodium actate, phenanthroline, etc, I would omit the transfer to the 100 mL volumetric flask and simply say it was filtered into a 250 mL volumetric flask. By the way, this transfer is another place, but a small place, where some of the iron in the sample may have been lost.
The 250 mL volumetric flask was filled with 10 mL of sodium acetate bywith a graduated cylinder, 1 mL of hydroxylamine hydrochloride by with a micro one wordliter pipette and 10 mL I would call this 1,10 phenanthroline bywith a graduated cylinder. Then the volumetric flask was fillednot to the mark with distilled water and the contents of the flask were mixed thoroughly.so, the next step was to dilute the solution and fill it with distilled water and shake it up to mix the iron phenanthroline solution up.
After testing the five solutions in the volumetic flasks Again, I'm confused here. All you have talked about so far is the one 250 mL volumetric flask (unless I've missed something) so I don't know where the five volumetric flasks came from, the next step was to take the iron phenanthroline solution in the volumetric flask when it was ready to be inserted into an Ocean Optics USB2000+ Miniature Fiber Optic Spectrometer.
First The the cuvet had to be wasfilled with distilled water and wasomit was placed into the spectrometer and set closest to zero, the spectrometer was set for about .077, and then the volumetric flask with the solution of iron-phenanthroline was tested in the cuvet at 510.3 nm for the wavelength of maximum absorbance. Why was the unit set to 0.077 if you were trying to set it to zero?
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