10.4. To determine tungsten, we used the oxidation reaction of n-phenylenediamine with potassium iodate, catalyzed by W(VI) compounds. Three volumetric flasks with a capacity of 50.00 ml were filled with 1.00; 3.00; 5.00 ml of standard solution with T(Na2WO4/W)=4.00*10-5 g/ml. After adding reagents and bringing the volume of solutions to the mark, we measured the optical density A depending on time t and determined the tangents of the slope angles of the straight lines in A-t coordinates. tga1=0.190 tga2=0.520 tga3=0.860. Construct a calibration graph tga-Cw. A sample of tungsten production slag m after fusion was dissolved and the volume of the solution was brought to 100.0 ml. 10.0 ml of the resulting solution was added to a 50.0 ml flask, reagents were added, adjusted to the mark, and the kinetic curve was recorded. Found the value of tgax. Determine the tungsten content (g) in 1 ton of slag using the following data:
option 1
Weight m, g 1.50
tgax 0.270

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