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MnO(4)^(-) +8H^+ +5e^- to Mn^(2+) +4H...

`MnO_(4)^(-) +8H^+ +5e^- to Mn^(2+) +4H_2 O ,E^@ = 1.51 V `
`MnO_(4)^(-) +4H^+ +2e^- to Mn^(2+) +2H_2 O ,E^@ = 1.23 V `
` E_(MnO_(4)^(-) "|" MnO_(2))`is

A

`1.70 v`

B

`0.91 V`

C

`1.37 V`

D

`0.548 V`

Text Solution

Verified by Experts

The correct Answer is:
A
`MnO_(4)^(- ) + 8H^( +) + 5e^(- ) to Mn^(2+) + 4 H_2 O , E^@ = 1.51 V `
` Delta G_(1)^(@) =- 5 ( 1.51 )F =- 7.55 F `
`MnO_2 +4H^( +) +2e^(-) to Mn^(2+) +2 H_2 O , E^@ = 1.23 V `
`Delta G_(2)^(@) =- 2 (1.23 ) F= - 2.46 F `
on subtracting
`MnO_(4)^@ =- 5 ( 1.51 ) F = - 7.55 F `
`E_("MnO_(4)^(-) |MnO_2 ) ^@ = (Delta G_(3) ^(@) )/(-nF) =(-5.09 F)/(-3F) = 1.70 V `
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