128. Solving a chemistry problem

128. Solving a chemistry problem

To determine tungsten, we used the reaction of oxidation of the iodide ion with hydrogen peroxide. 3.00 5.00 8.00 ml of sodium tungstate solution with Т Na2WO4/W=1.045*10-7 g/ml was added to three 50.0 ml volumetric flasks. The test solution was also placed in a 50.0 ml volumetric flask. After adding the reagents (KCl, HCl, starch, H2O2) and bringing the volume of the solutions to the mark, the optical density A was measured as a function of time t for all solutions. According to the data given in the table, construct graphs in the coordinates A-t and tgα-Cw. Determine the content of tungsten (g) in the studied solutions:
Option 3
t, min 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Standard solutions, ml
3.00 0.0065 0.077 0.093 0.107 0.120 0.136 0.150 0.165 0.178
5.00 0.115 0.140 0.166 0.192 0.220 0.246 0.300 0.327
8.00 0.180 0.220 0.262 0.302 0.340 0.380 0.420 0.455 0.490
III - option 0.145 0.180 0.210 0.245 0.280 0.310 0.345 0.375 0.413

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