Iron ore can be treated with HCl and various reagents to convert the iron to Fe2+, which can then be assayed by titration with permanganate.
Fe2+ + MnO4- ? Fe3+ + Mn2+
A 4.855-g sample of ore was processed into 500.0 mL of acidic solution, and a 100.0-mL aliquot of this solution required 19.74 mL of 0.1058 M KMnO4 to reach the titration endpoint. What was the mass percent of iron in the ore sample?