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Determine the concentrations of manganese in a pill.<br />Objectives: <br />• Get absorbance of various dilutions of the tablet.<br />• Determine the concentration of manganese in a pill.<br />Introduction<br />In this laboratory you will be weighing, mixing and calculating the concentration of manganese in a pill called Arthu Z with 4mg of manganese. Manganese is a chemical element, designated by the symbol Mn, with an atomic number of 25. It is found as a free element in nature (often in combination with iron), and in many minerals. As a free element, manganese is a metal alloy metal with important industrial uses, particularly in stainless steels. Also is an abundant mineral in foods such as nuts and grains and also in vitamins, such as Arthuan Z and Centrum. The students will crush the pill, add water and heat and make dilutions. Apart from this, will be added some acids that can react with the pill and can give you signal of presence of manganese in the solution. Some signs are: change of color and more density of the solution. A weighted by differentiation is a simple method to determine the mass of a series of samples. This method is through a container, in which the solid is added, weights it and then the amount you want measure will be subtract to the mass of container and the result of the balance wight will be the is where the balance has to come through the reduction of the solid. When the solution is prepared, it will be filtered in form of quantitative transfer. The quantitative transfer means that any full material or substance is transferred from one place to another. The process is as follows: take the solution to the filtering, the solid particles that remain in the container, water is added and still adding this to the filtrate.<br />Procedure<br />Arthuan Z is 4 mg tablet of Manganese.<br />Protocol<br />1. Get 2 pills and weighs both.<br />2. Taking an average of two pills.<br /><ul><li>1.2587g+1.2623g2 = 1.2605g</li></ul>3. Find the percentage of manganese in the pill.<br /><ul><li>0.004g1.2605 x 100 = 0.31%
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a. Bottle weights with the solid. Record the mass.
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b. Wrap the bottle with a paper towel, which will be use as a handle and drive them out gradually to a solid 250mL beaker until the mass of the bottle comes to a difference of 0.6g.</li></ul>6. Analysis of manganese in a vitamin pill.<br />Masa inicial de la botella:<br /><ul><li>It's supposed to be: 16.9305g - 0.6g = 16.3305
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Vitamin sample mass: 0.5936g</li></ul>7. Add 50mL of 4.0M HNO3<br />8. Add 2.5mL of H3PO4 (conc.) to the 3 solutions.<br />- No reaction occurred<br />9. Weighs 0.25g sodium periodate twice.<br />10. Add to 2 aliquots 0.25g sodium periodate. Do not add to the 3 solution, because one of them will be the control solution.<br />11. Heat the two solutions until a change occasionally happen for 15 minutes.<br />- Changing from yellow to purple, with a sign that the solution has concentration of manganese.<br />* When removed from heat, the solutions turn colorless. Then we added more than 0.10g of sodium periodate.<br />12. Heat it again and record the observations.<br />- Colorless solution completely changed to purple.<br />Part #2<br /><ul><li>Add 6 mL KMnO4 to a volumetric flask of 10mL and dilute with water.
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2mL of the solution in volumetric flask, to another volumetric flask of 100ml and dilute with water.
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Fill a 50mL of a burette at the 0.00 ± 0.001mL
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Make 8 dilutions (aliquot) in a volumetric beaker of 25.00 mL.</li></ul>Results:<br />Part #1:<br /><ul><li>The weight of: #1 pill- 1.2587g and #2 pill- 1.2623g. We calculated the average 1.2605g.
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The percent of the concentration of manganese in the pill was f 0.31%.
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With HNO3 4.0M, the vitamin diluted and turn yellow.
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Then, we filtrated the solution, added H3PO4 (conc.) and made 3 aliquote.
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When we heated two aliquot, changed the color from yellow to purple. </li></ul>Part #2:<br />MillilitersTransmittanceConcentration = V(3.80 x 10-425.001mL90.91.50 x 10-53mL76.64.60 x 10-55mL64.17.60 x 10-57mL54.21.06 x 10-49mL45.21.37 x 10-410mL40.91.52 x 10-412mL34.61.82 x 10-415mL26.72.28 x 10-4Sample #164.6Sample #263.0Average= 63.8<br /><ul><li>With the graph data:
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Absorbance = -log[64.6100] = 0.189767</li></ul>Y= 2.5139 x 103x + 1.9785 x 10-3<br />0.189767-1.9785 x 10-32.5139 x 103=x<br />7.47006762 x 10-5 = x<br />Calculation:<br />7.47006762 x 10-5(0.025L)(1mol Mn1mol KMnO4)100.00mL8.00mL(54.938g Mn1 mol Mn=0.00128g in 0.5936g<br />0.00128g(1.2605g)0.5936g=x<br />0.002718g(1000) = x<br />2.718mg of manganese in ArthuZ = x<br /><ul><li>After calculate the x with the graph, the mg of manganese in the pill is 2.718mg.</li></ul>Conclusion<br />In conclusion, for every investigation that is going to be done in the scientific world there is a science that has the appropriate methodology to find what you are looking for. In this case our objectives were to find the concentration of manganese in a vitamin supplement pill. This was the main goal; the science that had the procedure and concepts necessary for this purpose was analytical chemistry. Analytical chemistry concentrates in the analysis of chemical components in materials. For that reason the other objective, determining the absorbance of various dilution of the tablet, was needed. Determining absorbency is the method that is used to determine concentrations of a sample.the hypothesis that we stated was that the concentration of manganese will result less than the quantity that the label says. To confirm this hypothesis an experiment was designed, it can be divided into three main parts: the first step of the process was the preparation of three aliquots that contain the dilutions of the pill, second step is the preparation of another eight aliquots with known concentration of manganese for comparison, final step is the measuring of the transmittance with the spec-20 and converting this results in to the milligrams of manganese present in the pill. After many calculations there was found 2.718mg of manganese. Our hypothesis was confirmed as true. The only possible error that could significantly affect the results is that in the filtration of the pill sample some of the pill was left behind. Besides that the results are very reliable. We can see that many pharmaceutical companies are not properly analyzing their products. Federal agencies should be stricter with the production of supplements. <br />
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