Calculate the weight percent of ascorbic acid in a tablet of Vitamin C from the following data:A 80 mg sample of a crushed Vitamin C tablet was dissolved in 40 mL of H2SO4 and 20 mL of water. Two grams of KI and 40. mL of 0.00653 M KIO3 solution was added, and the mixture titrated to a starch endpoint. The titration required 15 mL of 0.0510 M thiosulfate solution. I know the answer is 88%, but how did they get it?

The Answer is 88%

Explanation:

The balanced ionic equation of the reaction

Looking at the above reactions

   The original number of moles of = 3 × number of moles of

                                                                = 3 × volume × concentration of

Note: The formula for number of moles is volume × concentration

                                                                mol

The number of moles of left after its reaction with ascorbic  acid

                         = x moles of

                          = x volume x concentration of    

Note: The division by 1000 is to convert mill liter to liter

                             Moles of ascorbic acid = moles of reacted

Hence

              Mass of ascorbic acid = moles of ascorbic acid × molar mass of ascorbic acid

 Weight% of ascorbic acid = mass of ascorbic acid/mass of sample x 100%

                                             = 70.55/80  × 100%

                                              = 88.1%