Question

Calculate the average mass (in milligrams) of ascorbic acid (176.12 g/mol) in each tablet. Procedure: Weigh...

Calculate the average mass (in milligrams) of ascorbic acid (176.12 g/mol) in each tablet.

Procedure:

Weigh out a 0.40 g - 0.50 g sample. Dissolve in 50 mL of 1.5M H2SO4; add about 5 g KBr. Titrate immediatly with standard KBrO3 to the first faint yellow due to excess Br2. Record the volume of KBrO3 used. (Total Used- 48.54 mL) Add 3 g of Kl and 5 mL of starch indicator; back-titrate with standard 0.05 M Na2S2O3. (Total used to back-titrate - 3.80 mL)

***Concentration of KBrO3- 0.015M

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