783a. The content of ascorbic acid in the medicinal product was determined by coulometric titration. To do this, the drug tablet was dissolved in a volumetric flask with a capacity of Vk, the volume of the solution was brought to the mark with water and the initial analyzed solution was obtained. An aliquot of this solution with a volume of Va was placed in a coulometric cell, an excess of potassium bromide was added, and coulometric titration of ascorbic acid was carried out with electrogenerated bromine at a constant current I for time t.
During the titration, ascorbic acid is oxidized by bromine to dehydroascorbic acid, while one molecule of acid reacts with 2 molecules of bromine.
According to the data below, calculate the content of ascorbic acid in a tablet of the drug. The molar mass of ascorbic acid C6H8O6 is 176.13 g/mol.
variant Vk, ml Va, ml I, mA t
a 200 10 70 6 min 25 s

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