Iron(II) ions catalyze the oxidation of luminol by H2O2,. The intensity of the resulting chemiluminescence has been shown to increase linearly with iron(II) concentration from 10-10 to 10-8 M.
Exactly 1.00 mL of water was added to a 2.00-mL aliquot of an unknown Fe(II) solution, followed by 2.00 mL of a dilute H2O2 solution and 1.00 mL of an alkaline solution of luminol. The chemiluminescence form the mixture was intergrated over a 10.0-s period and found to be 14.3.
To a second 2.00-mL aliquot of the sample was added 1.00 mL of a 3.58 × 10-5 M Fe (II) solution followed by the same volume of H2O2 and luminol. The integrated intensity was 33.3. Find the concentration of Fe (II) in the sample.