140. Solving a chemistry problem

140. Solving a chemistry problem

48. From a sample of steel weighing 0.2 g after appropriate processing, 100.0 ml of a solution containing MnO4 ⎯ and Cr2O72– was prepared, and its optical density was measured with light filters with λeff = 533 nm and λeff = 432 nm (A533, A432). In six volumetric flasks with a capacity of 100.0 ml were placed 5.00; 8.00; 10.00 ml of a standard solution of permanganate [T (Mn) = 0.0001090] or dichromate [T (Cr) = 0.0001210], diluted with water to the mark and photometric under the same conditions, when photometric obtained the following data - table 6.
Parameter KMnO4 K2Cr2O7
V, ml 5.0 8.0 10.0 5.0 8.0 10.0
A533 0.23 0.365 0.46 0.0 0.0 0.0
A432 0.095 0.15 0.19 0.43 0.64 0.78

Determine the mass fraction (%) of manganese and chromium in steel, if the optical density presented
A533 0.37
A432 0.72

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