1. Iodimetric Titration of Vitamin C
By: Mohammad Mashal

2. Directions:
Dissolve two tablets in 60 mL of 0.3 M H2SO4.
Add 2 g of solid KI and mL of standard KIO3.

3. 60 mL 0.3 M H2SO4.
2 g of KI.
50.00 mL of standard KIO3.
I I(-1) I(-1)3

4. Then titrate with standard thiosulfate
until the solution has a (pale blue) color.
I(-1) S2O(-2) 3  3I(-1) + Tetrathionate

5. While Titration
Add 2 mL of starch indicator just before the end point.

6. Q: why we using back titration in this experiment ?

7. A: because the end point is clearer than the end point of the direct titration.