6. Solution to Chemistry Problem

6. To determine iodide ions, the oxidation reaction of arsenite with potassium iodate, catalyzed by I- ions, was used. The method of additions at a fixed concentration of the reaction product was used. A sample of biological material weighing m g was dissolved in 25.00 ml of water after mineralization and appropriate treatment. 5.00 ml of the resulting solution were placed in two 25.00 ml flasks, and 1.00 ml of a standard iodide solution with a concentration of 0.5 μg/ml was added to one of them. Reagent solutions (KIO3, Na3AsO3, citrate buffer) were added to both flasks under the same conditions, the volumes were brought up to the mark with water, and the reaction completion time in each flask was determined from the polarographic data: tx and tх st
Option 1 2 3 4
tx 19.6 14.7 11.1 16.3
tх st 9.1 8.2 5.7 7.8
m, g 1.000 1.200 1.500 1.700
Solution for option 1