Question

reducing character increases from hf to hi. Why?

Answer 1

The decreasing thermal thermal stability of the hydrogen halides from HF to HI indicates that the reducing character increases down the group as :

HF < HCl < HBr < HI

Thus, HF is not a reducing agent at all. HCl is a weak reducing agent. HBr is a stronger reducing agent while HI is the strongest reducing agent among all the hydrides.

Answer 2

Hey !!

Reducing character is a measure of the ability of the molecule to get oxidised. More reducing character means that the molecule gets oxidised easily. In case of halogen acids the tendency to get oxidised is measured by its ability to lose hydrogen.

    Down the group, as the size of halogen increases, the X ---- H bond becomes weak and the tendency to lose hydrogen increases. Hence down the group reducing character increases.

Good luck !!