To determine the amount of magnetite (Fe3O4) in an impure ore, a XXXXXXXXXXg sample is dissolved in concentrated HCl, giving a mixture of Fe2+ and Fe3+. Then, Fe2+ is oxidized to Fe3+ by adding HNO3...

To determine the amount of magnetite (Fe3O4) in an impure ore, a 1.7832 g sample is dissolved in concentrated HCl, giving a mixture of Fe2+ and Fe3+. Then, Fe2+ is oxidized to Fe3+ by adding HNO3 and diluting with water. Fe3+ is precipitated as Fe(OH)3 by adding NH3. Filtering, rinsing and igniting the precipitate provides 0.9179 g of pure Fe2O3. Calculate the %w/w Fe3O4 in the sample.