a 3.00g sample containing Fe3O4 , Fe2O3 & an inert impure substance, is treated with excess of KI sol. in presence of dil.H2SO4. The entire iron is converted into Fe2+ along with the liberation of iodine. The resulting sol. is diluted to 100ml. A 20 ml of the diluted sol. requires 11ml of 0.5M Na2S2O3 sol. to reduce the iodine present. A 50ml of the diluted sol. after complete extraction of the iodine requires 12.80 ml of 0.25 M KMnO4 sol. in dil. H2SO4 medium for d oxidation of Fe2+. Calc. the % of Fe2O3& Fe3O4 in the original sample.

Samidha M.D , 13 Years ago

Grade 12