Calamine, which is used for relief of skin irritations, is a mixture of zinc and iron oxides. A 1.056-g sample of dried calamine was dissolved in acid and diluted to 250.0 mL. Potassium fluoride was added to a 10.00-mL aliquot of the diluted solution to mask the iron; after suitable adjustment of the pH, Zn2+ consumed 38.37 mL of 0.01133 M EDTA. A second 50.00-Ml aliquot was suitably buffered and titrated with 2.30 mL of 0.002647 M ZnY2- solution: Fe3+ + ZnY2- → FeY- + Zn2+
Calculate the percentages of ZnC and Fe2C3 in the sample.