Question

A student makes a mistake while preparing a vitamin C sample for titration and adds the potassium iodide solution twice. How will the larger quantity of KI influence the amount of NBS needed to titrate the sample? a. Increase it. b. Decrease it. c. Will have no effect on it.

Answer 1

The added KI does not have any impact  

The reaction invovles Titration of vitaminc ( Ascorbic acid)

ascorbic acid + I₂ → 2 I⁻  +  dehydroascorbic acid

the excess iodine is free reacts with the starch  indicator, forming the blue-black starch-iodine complex.  

This is the endpoint of the titration. since alreay excess KI is added ( the source of Iodine), it does not have an influence.

Answer B

Hope this helps!