Question

A 125 mL sample of orange juice was titrated using a redox reaction to the equivalence point with the addition of 7.6 mL of a 0.0025M iodine (I2) solution. What is the concentration of vitamin C (C6H8O6) in this sample? C6H8O6(aq) + I2(aq) ® C6H6O6(aq) + 2I–(aq) + 2H+(aq)

Answer 1

As per the balanced chemical equation, one-mole vitamin c react with one-mole iodine. (given)

Number of moles of iodine in 7.6 mL 0.0025 M iodine solution = (0.0025/1000) x 7.6 = 0.000019 moles

(Kindly note that molarity is the number of moles of solute in 1000 mL of solution)

Thus, the number of moles of vitamin c in 125 mL = 0.000019 moles

converting it to molarity

(0.000019/125) x 1000 = 0.000152 M

Concentration of vitamin c in the orange juice is 0.000152 M