Q. A 3.0 g sample containing Fe3O4,Fe2O3 and an inert impure substance is treated with excess of KI solution in presence of dilute H2SO4. The entire iron is converted to Fe2+ along with the liberation of iodine. The resulting solution is diluted to 100 mL. A 20 mL of the dilute solution requires 11.0 mL of 0.5 M Na2S2O3 solution to reduce the iodine present. A 50 mL of the diluted solution after complete extraction of iodine requires 12.8 mL of 0.25 M KMnO4 solution in dilute H2SO4 medium for oxidation of Fe2+. Calculate the percentage of Fe2O3 and Fe3O4 in the original sample.
