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Justify Giving Reactions that Among Halogens, Fluorine is the Best Oxidant and Among Hydrohalic Compounds, Hydroiodic Acid is the Best Reductant. - Chemistry

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Long Answer

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

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Solution

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

\[\ce{F_{2(aq)} + 2Cl-_{(s)} -> 2F-_{(aq)}  + Cl_{(g)}}\]

\[\ce{F_{2(aq)} + 2Br-_{(aq)} -> 2F-_{(aq)} + Br_{2(l)}}\]

\[\ce{F_{2(aq)} + 2I-_{(aq)} -> 2F-_{(aq)} + I_{2(s)}}\]

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.

\[\ce{2HI + H_2SO_4 -> I_2 + SO_2 + 2H_2O}\]

\[\ce{2HBr + H_2SO_4 -> Br_2 + SO_2 + 2H_2O}\]

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

\[\ce{4I-_{(aq)} + 2Cu^{2+}_{(aq)} -> Cu_2I_{2(s)} +  I_{2(aq)}}\]

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.

Concept: Oxidation Number - Redox Reactions as the Basis for Titrations
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APPEARS IN

NCERT Chemistry Part 1 and 2 Class 11
Chapter 8 Redox Reactions
EXERCISES | Q 8.15 | Page 281
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