2. Solving a chemistry problem

5. To determine the iron content in beverages, photocolorimetry can be used. Ferrous sulfate (3) is used to prepare calibration solutions. The molar absorption coefficient of the complex of iron with sulfosalicylic acid at a wavelength of 416 nm is 4000. Determine which sample of Fe2(SO4)3 • 9H2O must be dissolved in 50 ml of water so that a colored a solution whose optical density in a cuvette with a layer thickness of 2 cm would be 1.5.