Pre-Lab Assignment
1. A 0.1017 g sample of KBrO3 was dissolved in dilute acid andtreated with an excess of KI. BrO3¯ + 9I¯ + 6H+ Br¯ + 3I3¯ + 3H2OThe generated I3¯ required 27.39 mL of a Na2S2O3 solution to reduceit to I¯. Use the above equation and those found in theintroduction to determine the molarity of the Na2S2O3 solution.
2. The following data was obtained for an iodometric titrationof an ascorbic acid tablet.
Mass of tablet: 1.2381 g
Mass of sample analyzed: 0.2483 g
Vol. of 0.0166 mol•L-1 KIO3: 25.00 mL
Vol. of 0.0198 mol•L-1 Na2S2O3 to reach endpoint: 11.01 mL
Using the equations found in the introduction, determine: themass of ascorbic acid in the sample analyzed and the mass ofascorbic acid contained within the tablet.
