200ml of the standard oxalic acid solution was placed

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then sufficient water was added to bring the solution to the calibration mark. 20.0ml of the standard oxalic acid solution was placed into a clean 250.0ml Erlenmeyer flask with a transfer pipette and 10ml of deionized water and 15.0ml of 3.0M sulfuric acid was added to the solution and heated to 80°C. The flask was removed the heat and titrated with the KMnO 4 solution in a burette until the solution showed a faint pink color of excess KMnO 4 for at least 30 seconds. This was repeated 2 more times. In order to determine the percentage of oxalate in the synthesized compound, 20ml of solution A was substituted for the 20ml oxalic acid solution. The same amounts of deionized water and sulfuric acid was used. The solution was heated to 80°C and titrated with potassium permanganate as before and done 2 more times. Results Table 1: Synthesis of K 3 Fe(C 2 O 4 ) 3 3H 2 O Weight of Fe(NH 4 ) 2 (SO 4 ) 2 6H 2 O (g) 5.0g Moles of Fe(NH 4 ) 2 (SO 4 ) 2 6H 2 O (mol) .01275 moles
Theoretical yield of K3Fe(C2O4)3•3H2O (g) 6.26g Actual yield of K3Fe(C2O4)3•3H2O (g) 1.59g Percent yield of K3Fe(C2O4)3•3H2O 25.40% Table 2: Calibration Curve ([Fe 3+ ], Absorbance) Conc. (x10 - 5 M) Absorbance 2 .269 4 .449 6 .674 8 .954 Solution .661 Graph 1- Calibration curve of Fe(C 12 H 8 N 2 ) 3 2+
Solution Concentration is approximately 5.654 x10 -5 M Table 3 Analysis of iron in K 3 Fe(C 2 O 4 ) 3 3H 2 O Weight of K 3 Fe(C 2 O 4 ) 3 3H 2 O used in solution A (mol) 1g Moles Fe 3+ in sln A (mol) 2.04 x10 -3 mol Weight Fe 3+ in sln A (g) .114g Actual Weight % of Fe 3+ in of K 3 Fe(C 2 O 4 ) 3 3H 2 O 11.4% Theoretical Weight % of Fe 3+ in of K 3 Fe(C 2 O 4 ) 3 3H 2 O 11.3% Percent error in percentage of Fe 3+ .88% Table 4 Standardization of KMnO 4 solution unknow n
Weight of H 2 C 2 O 4 2H 2 O 1.58g Molarity of H 2 C 2 O 4 2H 2 O Solution .05M Volume of H 2 C 2 O 4 2H 2 O Solution 20 mL 20 mL 20 mL Moles of oxalate .001mol .001mol .001mol Initial buret reading 1.4ml 9.4ml 6.5ml Final buret reading 23.5ml 31.6ml 28.5ml Volume of KMnO 4 Solution 22.1ml 22.2ml 22.0ml Moles of KMnO 4 .0004mol .0004mol .0004mol Molarity of KMnO 4 Solution 1.81x10 -5 M 1.80x10 -5 M 1.81x10 -5 M Avg. Molarity of KMnO 4 Solution: 1.81x10 -5 M Table 5 Titration of Solution A Volume of Solution A 20.0 mL Initial Buret Reading .4ml 2.9ml 1.6ml Final Buret Reading 26.5ml 28.5ml 28ml Volume of KMnO 4 solution 26.1ml 25.6ml 26.4ml Moles of KMnO 4 4.72x10 -4 4.63x10 -4 4.78x10 -4 Moles of oxalate .00118 .00116 .00119 Avg. Moles of Oxalate: 0.00118 Table 6 Analysis of oxalate in K 3 Fe(C 2 O 4 ) 3 3H 2 O Average moles of oxalate .00118 moles Total moles of oxalate in solution A .0059 moles Total weight of oxalate .518g Wt. K 3 Fe(C 2 O 4 ) 3 3H 2

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