JEE MainChemistryp Block Elements (Group 13 & 14)
The standard reduction potentials E^ ( M ⁴⁺/ M ²⁺) for Group 14 elements vary due to the inert pair effect. Among the following bimolecular redox reactions, which one is thermodynamically most feasible (has the most positive E^ value)?
Options
- APb ²⁺ + Sn ⁴⁺ Pb ⁴⁺ + Sn ²⁺
- BGe ⁴⁺ + Pb ²⁺ Ge ²⁺ + Pb ⁴⁺
- CPb ⁴⁺ + Ge ²⁺ Pb ²⁺ + Ge ⁴⁺
- DSn ⁴⁺ + Ge ²⁺ Sn ²⁺ + Ge ⁴⁺
Correct answer
C. Pb ⁴⁺ + Ge ²⁺ Pb ²⁺ + Ge ⁴⁺
Step-by-step solution
The thermodynamic feasibility of these reactions depends on the relative stability of the +2 and +4 oxidation states, which is governed by the inert pair effect. Down Group 14 (Ge, Sn, Pb), the stability of the +2 oxidation state increases and the stability of the +4 oxidation state decreases. Consequently, the tendency to undergo reduction from +4 to +2 increases down the group. This means the standard reduction potential E^ ( M ⁴⁺/ M ²⁺) is highest for Pb and lowest for Ge. Thus, Pb ⁴⁺ is the strongest oxidizing