Question

Assuming 80mg of vitamin C present in 29.57 mL of orange juice, how many milliliter a of 0.0102 M KIO3 would be required to reach the stoichiometric point?

Answer 1

molar mass of vitamin C = 176.12 g/mol

moles of vitamine C = 80 x 10^-3 / 176.12 = 4.54 x 10^-4

Equation 1 : IO3- (aq) + 6 H+ (aq) + 5 I- (aq) --------------> 3 I2 (aq) + 3 H20

The iodine formed will react with the ascorbic acid.

Equation 2 : C6H8O6 + I 2 -------------> C6H6O6 + 2 I- (aq) + 2 H+ (aq)

from 1 and 2

3 moles of vitamin C ---------------> 1 mol IO3-

4.54 x 10^-4 moles of vitamin C --------> x mol IO3-

x = 4.54 x 10^-4 / 3

x = 1.514 x 10^-4

moles of IO3- =  1.514 x 10^-4

molarity of IO3- = 0.0102 M

volume = moles / molarity

= 1.514 x 10^-4 / 0.0102

= 0.0148 L

volume of KIO3 = 14.84 mL