Given below are the half - cell reactions: Mn2+ + 2e– → Mn; Eo = – 1.18 V 2 (Mn3+ + e– → Mn2+) ; Eo = +1.51 V The Eo for 3Mn2+ → Mn + 2Mn3+ will be:

Engineering

Chemistry

Activity or Electrochemical Series

EMF Calculation and Galvanic Cell

Nernst Equation

Question

Given below are the half - cell reactions:

Mn²⁺ + 2e^– → Mn; E^o = – 1.18 V

2 (Mn³⁺ + e^– → Mn²⁺) ; E^o = +1.51 V

The E^o for 3Mn²⁺ → Mn + 2Mn³⁺ will be:

– 0.33 V; the reaction will occur

– 2.69 V; the reaction will not occur

– 0.33 V; the reaction will not occur

– 2.69 V; the reaction will occur

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Mn⁺² + 2e^– → Mn; Eº = –1.18 V

Mn⁺³ + e^– → Mn⁺²; Eº = +1.15 V

Given reaction: 3Mn⁺² → Mn + 2Mn⁺³ is disproportionation reaction

$∴ E^{0} = E_{{Mn}^{+ 2} / Mn}^{0} + E_{{Mn}^{+ 2} / {Mn}^{+ 3}}^{0}$

= –1.18 – 1.51

= –2.69 V

$∵$ Eº is –ve

$∴$ reaction cannot occur at standard condition.

(D) is the answer