Question

Justify giving reactions that among halogens, fluorine is the best oxidant and among hydrohalic compounds, hydroiodic acid is the best reductant. 

Answer 1

F₂ can oxidize Cl^– to Cl₂, Br^– to Br₂, and I^– to I₂ as: 

On the other hand, Cl₂, Br₂, and I₂ cannot oxidize F^– to F₂. The oxidizing power of halogens increases in the order of I₂ < Br₂ < Cl₂ < F₂. Hence, fluorine is the best oxidant among halogens. 

HI and HBr can reduce H₂SO₄ to SO₂, but HCl and HF cannot. Therefore, HI and HBr are stronger reductants than HCl and HF. 

Again, I^– can reduce Cu²⁺ to Cu⁺, but Br– cannot. 

Hence, hydroiodic acid is the best reductant among hydrohalic compounds. Thus, the reducing power of hydrohalic acids increases in the order of HF < HCl < HBr < HI.