Question

Oxidation-Reduction Titrations I: Determination of Oxalate Č. Analysis of Oxalate Complex or Unknown Mass of sample Trial Trial 2 Trial 3 Weighing bottle initial mass Weighing bottle final Mass of sample Titration Final reading Initial reading O,1121 Volume of KMnO4 Millimoles of oxalate, C,0,2- Mass of oxalate, C2042 Percent oxalate, C,042 Average percent oxalate If you analyzed your oxalate complex from your experiments, complete the following: Standard devia eoretical percent oxalate in your complex (show calculations) experimental % oxalate purity x 100%

KMnO4 Molarity is .02107M

.02107

Answer 1

The reaction that occurs is:

2MnO4- + 5C2O42- + 16H + → 2Mn2 + + 10CO2 + 8H2O

We calculate the millimoles of C2O4-2:

mmol C2O4-2 = M * V * 5 * 1000/2 = 0.02107 M * 0.0173 L * 5 * 1000/2 = 0.911 mmol

Trial 2: 0.874 mmol

Trial 3: 0.864 mmol

We calculate the grams of C2O4-2:

g C2O4-2 = mmol * MM / 1000 = 0.911 mmol * 88 g / mol / 1000 = 0.080 g

Trial 2: 0.077 g

Trial 3: 0.076 g

We calculate the percentage of oxalate:

% ox = g Oxalate * 100 / g sample = 0.080 * 100 / 0.1198 = 66.78%

Trial 2: 67.25%

Trial 3: 64.90%

Average: 66.31%

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