Question

If 28.70 mL of 0.0200 M KMnO4 is required to titrate a 0.250 g sample of K3[Fe(C2O4)3]*3H2O, what is the percent C2O42- in the complex? What is the percent purity of this complex?

Answer 1

To determine the percent C2O42- in the complex and its purity, we calculate the moles of KMnO4 used in the titration, find the corresponding moles of C2O42-, and then use the complex's molar mass to determine the mass percentages.

Step-by-step explanation:

The question involves determining the percent composition of C2O42- in a complex and the percent purity of the complex. This is done using the volume of a titrant, which in this case is a 0.0200 M KMnO4 solution, to titrate a given mass of the sample containing the complex K3[Fe(C2O4)3]*3H2O. The titration data allows us to calculate the moles of C2O42- present and, from there, determine the mass percent of oxalate in the complex and the overall purity.

Answer 2

The percent C₂O₄²⁻ in the complex K₃[Fe(C₂O₄)₃]*3H₂O is determined to be 50.4%, and this value is also the percent purity of the complex since the titration assumes all oxalate comes from the pure complex.

Step-by-step explanation:

To determine the percent C₂O₄²⁻ in the complex and the percent purity of K₃[Fe(C₂O₄)₃]*3H₂O, we need to perform a series of calculations based on the information given.

Step-by-Step Calculation

Find moles of KMnO₄ used: Moles = Molarity × Volume in liters = 0.0200 M × 0.02870 L = 5.74 × 10⁻⁴ moles.

The balanced chemical equation for KMnO₄ titrating C₂O₄²⁻ shows that the molar ratio is 2:5 (KMnO₄:C₂O₄²⁻). So, moles of C₂O₄²⁻ in the sample = 5.74 × 10-4 moles × (5/2) = 1.435 × 10-3 moles.

Calculate the mass of C₂O₄²⁻: Moles × Molar mass of C₂O₄²⁻ (88.02 g/mol) = 1.435 × 10-3 moles × 88.02 g/mol = 0.126 g.

Calculate percent C₂O₄²⁻ in the complex: (Mass of C₂O₄²⁻ / Mass of sample) × 100 = (0.126 g / 0.250 g) × 100 = 50.4%.

The percent purity of the complex is the same as the percent C₂O₄²⁻ as it is assumed all C₂O₄²⁻ comes from the pure complex.