Question

Why must you pour KIO[sub]3[/sub] into a beaker from the volumetric flask instead directly into the beaker oh NaHSO[sub]3[/sub].

Answer 1

Probably, you mean "the clock reaction". In this reaction amount of KIO3 is crucial. So, we need firstly to pour solution of KIO3 into the volumetric flask and then, well-known volume of solution pour to baker with NaHSO3.