A 0.1967 g sample of pure ascorbic acid is weighed out and dissolved in 50.0 mL of distilled water in an Erlenmeyer flask. One week later, when about one third of the water in the flask has evaporated, this solution is titrated against 0.01735 M K103 solution and requires 18.75 mL of it to reach the end point.
(a) What mass of ascorbic acid has been oxidized by the air over the week-long waiting period?