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MnO(4)^(-) + 8H^(+) + 5e^(-) rightarrow ...

`MnO_(4)^(-) + 8H^(+) + 5e^(-) rightarrow Mn^(2+) + 4H_(2)O`, `E^(@) = 1.51V`
`MnO_(2) + 4H^(+) + 2e^(-) righarrow Mn^(2+) + 2H_(2)O` `E^(@) = 1.23V`
`E_(MnO_(4)^(-)|MnO_(2)`

A

`- 1 V `

B

`-1.70` V

C

`+ 1` V

D

`1.70` V

Text Solution

Verified by Experts

The correct Answer is:
D
Eq(i) - Eq(ii)
`MnO_(4)^(-) + 4H^(+) + 3e^(-) to Mn underset(+4)(O_(2)) + 2 H_(2)O , E_(3)^(@) = ?`
`Delta G_(3)^(@) = DeltaG_(1)^(@) - DeltaG_(2)^(@) - n_(3) E_(3)^(@) F = - nE_(1)^(@) F - n_(2) E_(2)^(@) F - 3 E_(3)^(@) = (5 xx 1.51) - (-2 xx 1.23)`
`therefore - E_(3)^(@) = ((-5 xx 1.51) + (2 xx 1.23))/(3) = -1.70` V .
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