need help with the preparation of potassium iodate for a titration of thiosulfate

Question

I want to prepare a ca. 0.02M solution of Potassium iodate to react with 20-30mL of 0.1M Sodium Thiosulfate (Na₂S₂O₃.5H₂O), the volume required is 250mL, I know I will be required to add a certain mass of Potassium iodite ( KI) in the solution but I don’t know how to find the mass I know the concentration of KI is 10% (m/v)

Can you provide step by step on how to prepare the solution and the required mass of KI that will be needed to add to the potassium iodate.

Answer 1

In the first sentence, you say to prepare potassium iodate, then you say you need to add a certain mass of potassium iodite (KI). Iodate and iodite are not the same, and neither has the formula of KI. The formula KI is potassium iodide (note the difference in the suffixes). The current compound for the titration of thiosulfate is potassium iodate, KIO₃.

To make 0.02 M KIO₃, we take the molar mass of KIO₃ which is 214.0 g and the volume we need, which is 250 ml (0.250 L) and multiply: 0.02 mol/L x 0.250 L x 214 g/mol = 1.07 g dissolved in a total volume of 250 ml.

To make 10% potassium iodide (not iodite), you dissolve 10 g KI for every 100 mls of solution.

The normal titration requires the presence of the iodate and the iodide solution to be mixed and thus you create I₂ + H₂O which then reacts with I^- to produce I₃^-

I can't give you step by step how to prepare the solutions needed because you don't provide the actual procedure being used, and you provided the incorrect reagents (iodate, iodite, etc.)