79 Решение задачки по химии №07 909

147. Due to the low values ​​of dissociation constants (pK>9), the determination of phenols and their derivatives by acid-base titration is carried out in a non-aqueous medium. For potentiometric analysis, 100 cm3 of hydrolysis production waste water was acidified to pH=2, a salting-out agent (40% ammonium sulfate solution) and 17 cm3 of acetone were added. After extraction of phenol on a vibrating mixer, the organic layer was diluted with dimethylformamide (1:1) and placed in a cell for potentiometric titration. To determine the CTT, an indicator oxide-platinum electrode and a saturated silver chloride reference electrode were used. Determine the concentration of phenol in treated wastewater (mg/dm3) if 0.46 cm3 of 0.001 mol/dm3 of potassium hydroxide solution in isopropyl alcohol was used to titrate the sample. The degree of extraction of phenols from the aqueous medium is taken equal to 100%. (Molar mass of phenol is 94.12 g/mol).

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