The E° value for the Mn^3+/Mn^2+ couple is more positive than that of

Question

The \(E ^\circ\) value for the \(Mn^{3+}/Mn^{2+}\) couple is more positive than that of \(Cr^{3+}/Cr^{2+}\) or \(Fe^{3+}/Fe^{2+}\) due to change of 

(1) \(d^5\) to \(d^4\) configuration 

(2) \(d^5\) to \(d^2\) configuration 

(3) \(d^4\) to \(d^5\) configuration 

(4) \(d^3\) to \(d^5\) configuration

Answer 1

Correct option is (3) \(d^4\) to \(d^5\) configuration 

\(E ^\circ _ {Mn^{3+}/ Mn^{2+}} > E ^\circ _ {Cr ^{2+}}\) or \(E ^\circ _ {Fe ^{3+}/Fe^{2+}}\)

Electronic configuration of \(Mn^{3+} = [Ar] 3d^4\)

Electronic configuration of \(Mn ^{2+} = [Ar] 3d^5\)

Electronic configuration of \(Cr ^{3+} = [Ar]3d^3\)

Electronic configuration of \(Cr ^{2+} = [Ar]3d^4\)

As \(Mn^{3+}\) from \(d^4\) configuration goes to more stable \(d^5\) configuration (Half filled), due to more exchange energy in \(d^5\) configuration.