8. Analysis of hydrogen peroxide is based on its oxidation of iron (II) and photometric determination of excess iron (II) with 1,10-phenanthroline. To construct a calibration curve, 1.0 1.0 1.2 1.3 1.4 1.5 ml of a standard H2O2 solution with a concentration of 1.0 * 10-4 mol/l was placed in 50.0 ml volumetric flasks. Perchloric acid, sodium acetate, and iron(II) were added to each flask. 1,10-phenanthroline and diluted to the mark with water. We measured the relative optical densities using a reference solution with the highest H2O2 content (sixth solution) and obtained:
Volume of standard solution, ml 1.0 1.10 1.20 1.30 1.40 1.50
A, 0.340 0.270 0.205 0.135 0.070 0
Calculate the concentration (mol/l) of H2O2 if 20.0 ml of the test solution was diluted in a volumetric flask with a capacity of 500.0 ml, an aliquot of 5.0 ml was taken into a flask with a capacity of 50.0 ml, the above reagents were added, photometry was taken as when constructing a calibration scale graph and got the results: 1) Aotn=0.120 2Aotn=0.170 3) Aotn=0.255

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