A 3 g sample of haematite (iron ore containing Fe2O3) is dissolved in hydrochloric acid and the volume is made up to 250 mL. 25 mL of this solution was reduced with SnCl2. Unreacted SnCl2 was removed by extraction, and the residual solution needed 30 mL of 0.02 M acidified K2Cr2O7 solution to reach equivalence point. Determine the mass percentage of Fe2O3 in the ore.

A 3 g sample of haematite (iron ore containing Fe2O3) is dissolved in

1.	A 3 g sample of haematite (iron ore containing Fe2O3) is dissolved in hydrochloric acid and the volume is made up to 250 mL. 25 mL of this solution was reduced with SnCl2. Unreacted SnCl2 was removed by extraction, and the residual solution needed 30 mL of 0.02 M acidified K2Cr2O7 solution to reach equivalence point. Determine the mass percentage of Fe2O3 in the ore.
Answer» A 3 g sample of haematite (iron ore containing $F e_{2} O_{3}$ ) is dissolved in hydrochloric acid and the volume is made up to 250 mL. 25 mL of this solution was reduced with $S n C l_{2}$ . Unreacted $S n C l_{2}$ was removed by extraction, and the residual solution needed 30 mL of 0.02 M acidified $K_{2} C r_{2} O_{7}$ solution to reach equivalence point. Determine the mass percentage of $F e_{2} O_{3}$ in the ore.