I'm doing a lab report determination of ascorbic acid in vitamin C tablet. The equation used are:...

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Chemistry

I'm doing a lab report determination of ascorbic acid in vitaminC tablet.
The equation used are: IO₃^- + 8I^- + 6 H+ <--> 3 I₃^- + 3H2O
Back titration with thiosulfate: 2S₂O₃^-2 + I₃^---> S₄O₆^2- + 3I^-
This is my value from the lab:
Mass of Na2S2O3 (g) : 7.8459 g ; Mass of KIO3 (g) : 2.5272 g
Mol of KIO3 dispensed: 0.01181 mol
Mass of tablet: 0.5986 g; mass of pulverized tablet: 0.5708g
Volume of thiosulfate dispensed (mL): 29.9 mL
So far I calculated:
Mol thiosulfate: 0.002100 mol (not sure if its right)
Now I need to figure out how to find:
Mol of IO3- consumed by thiosulfate?
Mol of IO3- consumed by vitamin C?
Mol of ascorbic acid?
How do I find those?

Answer & Explanation Solved by verified expert

3.8 Ratings (702 Votes)

We can divide the experiment in parts to understand the process Step I Standardization of the provided solution of Na2S2O3 by titrating it with the I3 aq produced by the reaction of dissolved samples of primary standard KIO3s with excess KI Note The molar mass of KIO3 is 21400 gmol Step II Determination of the IO3 in the unknown by titrating with the Na2S2O3 the I3 aq generated by the reaction of pipetted samples of the unknown with excess I aq Here we use the 1M potassium iodide solution KIaq 1M hydrochloric acid solution HClaq Starch indicator Part 1 Preparation of the KIO3 Standard Samples See Answer

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