The concentration of iron in a vitamin tablet was determined using absorbance spectroscopy. A vitamin tablet was dissolved in 10 mL of 6 M HCl. The resulting solution was transferred to a 100.0 mL volumetric flask and diluted to volume with DI water. A 1.00 mL aliquot of the vitamin stock solution was transferred to each of 5 100.0-mL volumetric flasks. To each flask, 10 ml each of 2 g/L hydroquinone and 1 g/L o-phenanthroline are added, along with varying volumes of a 40.5 mg/L Fe3 stock solution. Each solution was diluted to volume and allowed to react for 10 minutes. The absorbance of the resulting solutions was measured at 515 nm. Required:
Determine the mg of iron in the vitamin tablet.