39. A 0.30 g sample of a standard aluminum alloy containing 12.5% ​​Si was dissolved in a 500 ml flask. To plot a calibration graph, aliquots of this solution were placed in 100 ml volumetric flasks, reagents were added - ammonium molybdate and iron (II) sulfate, and the volume was brought to the mark. The measurement of optical density relative to the first solution is given in the table.
Vst, ml 5.2 5.4 5.6 5.8 6.0
Arel 0.105 0.215 0.330 0.440 0.550
A 0.2500 g sample of the analyzed alloy was dissolved in 500 ml. A 5.0 ml sample was placed in a 100 ml volumetric flask, reagents were added and the optical density was measured as in the construction of the calibration.
Calculate the mass fraction (%) of silicon in the sample using the following data. Ax was 0.360.

If you cannot open the file or have any problems, do not rush to leave a negative review! Contact me and I will quickly help you solve the problem. After purchasing, please leave a positive review of the product :)