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UIUC CHEM 203 - Copper Iron Lab - 2

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Copper/Iron Stoichiometry LabAbstractThis lab used quantitative and qualitative analysis to confirm the state of Fe in thereaction between copper sulfate and iron. The Fe (1.9989g) reacted with a CuSO4 solution to produce Cu (2.3299g). The state of the Fe was then determined by finding the limiting reagent in the reaction and which was determined to be the iron powder. The percent yield in the end was 102.4%. IntroductionThe Issue of pollutants in water is becoming more and more of a problem as industry keeps contaminating the ever-depleting freshwater supplies. A solution to contain these contaminants has been researched and can be performed by the use of reduction by iron1. There is much research and work being done to reduce these pollutants such as bromine or dinitroluenes2 to their elemental state, which is much less harmful. The use of zero valent iron is essential to this success of reducing the Bromine from the water as stated by the department of civil engineering of the university of Hong Kong3. In this lab that, our goal is to reduce copper (II) sulfate with iron powder causing one of the two following reactions CuSO4(aq) + Fe(s)  Cu(s) + FeSO4(aq)3CuSO4(aq) + 2Fe(s)  3Cu(s) + Fe2(SO4)(aq)We will be performing a limiting reagent experiment to determine the formula for this copper. In the end of the experiment we will be able to determine which reaction was performed. If there is more moles of CuSO4 produced, than Iron was the limiting reagent and for the second reaction if the Cu produces to most moles than CuSO4 is the limiting reagent. One of the goals of this experiment is to find the limiting reagent by an experiment so by finding this we will also find the correct equation used. To perform this we will need to use a vacuum filtration method to separate the solution from product4.Materials and MethodsThis lab was carefully carried out by using the procedures shown in the lab manuel4. In the lab, 6.9985g of copper sulfate was added to 63 mL of DI water and heated, then 1.9989g of Fe powder was added to this solution, and the reaction was carried out under a fume hood. After the reaction was carried out, the beaker was left in the fume hood to cool, then left for further cooling at the lab station. This step was to ensure no sulfur gases were inhaled. The solution was then filtered by the vacuum filter in order to extract the copper. Next the copper was rinsed with 18 mL of DI water then 4 rinses with HCl of amounts 15 mL, 17 mL, 18 mL, 13 mL. The copper was dried for 10 minutes and not more to ensure copper was dry, but did not start to oxidize.Results (1)(2)2First, the empty crucible was massed on an analytical balance and found to be 30.7591g. (Table 1) The copper was filtered and then massed in the crucible and found to be 33.0890 g implying that the copper was 2.3299 g. In table 2, the moles of Cu, Fe and CuSO4 are shown. Table 1. Mass of Fe, CuSO4, and Crucible.Fe (g) CuSO4 (g) Empty Crucible (g) Crucible + Cu (g) Cu (g)1.9989 6.9985 30.7591 33.0890 2.3299Table 2. Moles and Molecular Weight of CuSO4, Cu, and FeSubstance Molecular Weight (g/mol) MolesCuSO4159.61 .043848Fe 55.85 .03579Cu 63.55 .03666To determine the limiting reagent, the actual yield needed to be compared with thetheoretical yield. If the Iron powder was the limiting reagent, then reaction 1 occurred therefore:1.9989 g Fe=.03579 mol Fe ×1 Mol Cu1 Mol Fe=0.03579 mol CuHowever if the CuSO4 was the limiting reagent then the following reaction (reaction 2) occurred.6.9985 g CuSO 4 ×3 mol Cu3 mol CuSO 4=0.043866 molCuSince the amount of copper obtained turned out to be 2.3299g the amount of moles yielded was .03666 mol. Therefore the reaction from reaction 1 took place. In addition to this CuSO4 is blue in color, and after the reaction there was a blue hue thus proving that there was CuSO4 in excess. Also the theoretical yield of Cu would have been .03579 moles of Cu, the but the actual yield was .03666 moles therefore making the percent yieldto be 102.4% yield.Error analysisNo mathematical error analysis neededDiscussion3The end goal of this experiment was to determine the oxidation state of the iron iniron sulfate from the reaction of CuSO4 and iron powder. This was determined by a very careful limiting reagent experiment. There were two possible results from this equation; both are discussed in the introduction. The end result produces FeSO4 and is found to be this by carefully massing the copper product after drying in a vacuum filter. There is a problem with some of the results. The actual yield was found to be 102.4%. This is a greater yield than that which is theoretically possible, but this yield can be accounted for. First the copper was left to dry on over the vacuum filtration. There could have been two possible sources of error in this area. If it was left to dry for not enough time, some DI water or HCl may have been left in the crucible while weighing it and could have caused too great a mass. Also if the copper was left over the crucible too long, the copper could have oxidized and produced a greater mass than what was theoretically supposed to happen.Second, though proper technique was used in the lab to ensure no dust or residue was left on the crucible, it was left on the lab table for a large portion of time. The proper technique included using a kim-wipe to touch the crucible. The problem arose when it was left out for an extended period of time. During this time dust or other debris would have been free to land on or in the crucible causing the final mass to increase, causing theactual yield to increase. The central theme to this reduction by iron experiment was the concept of limitingreagents. The possibility of two chemical reactions could have taken place, which are discussed in the introduction. Without the knowledge of limiting reagents this could not have been determined. In the results section the limiting reagent was calculated in both equations. Then it was compared to the table 2 results and it was found that the Fe was the limiting reagent in this reaction showing that the first reaction in the introduction was the one that was carried out. Also in case of major errors, the limiting reagent could have been determined by qualitative analysis. CuSO4 is blue in color. After the reaction is carried out if the color is close to the same at the end of the reaction, this proves the CuSO4 was in excess, showing the Fe was the limiting reagent. Several techniques


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