Question

outline the rationale for doing the iodine test using Hanus method , and chemistry of it

Answer 1

In the Hanus reaction, iodine monochloride (ICl) reacts with the unsaturated bonds to produce a di-halogenated compound.

Once the reaction is over, the amount of iodine that has reacted is determined by adding potassium iodide to the reaction. This results in the reaction of remaining unreacted ICl to form molecular iodine:

ICl + KI ----------> KCl + I₂

Now, I₂ is titrated with a standard solution of sodium thiosulfate (redox titration) using starch as the indicator

I₂ + 2 Na₂S₂O₃ --------> 2 NaI + Na₂S₂O₄