4. When determining vanadium by the method of additions, a sample of steel 0.5036 g was transferred into a solution and its volume was brought to 50.0 ml. Aliquots of the solution of 20.0 ml each were taken into two 50 ml volumetric flasks. A standard solution of vanadium was added to one of these flasks, after which its concentration became equal to 1.18 * 10-3 mol / l. Then hydrogen peroxide was added to both flasks and the solutions were made up to the mark. When measuring the optical density received Ax=0.20, Ax Ast=0.48 (with an absorbing layer thickness of 1 cm and a wavelength of 410 nm).

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