16 7-2 Titration Calculations Ascorbic acid (vitamin C) reacts with according to the equation Starch is used as an indicator in the reaction. The end point is marked by the appearance of a deep blue starch-iodine complex when the first fraction of a drop of unreacted remains in the solution. TI (a) Stundurdization: If 29.41 mL of iodine solution is required to react with 0.197 0 g of pure ascorbic acid, what is the molarity of the iodine solution?! (b) Analysis of Unknown: A vitamin C tablet containing ascorbic acid plus an inert binder was ground to a powder, and 0.424 2 g was titrated by 31.63 mL of iodine solution. Find the weight percent of ascorbic acid in the tablet (Formula mass of ascorbic acid = 176.124) 17