In this process first we need to liberate iodine to react with sodium thiosulfate.
First, sodium bicarbonate is added to a iodate-free solution of potassium iodide. The mixture is shaken until the salts dissolve, then conc. hydrochloric acid is added. The solution is shaken again, then covered and keept in a dark place. I have two questions here:
- What is the role of sodium bicarbonate here?
- Can conc. sulfuric acid be used to provide the acidic media instead of conc. hydrochloric acid?