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Given that the standard reduction potent...

Given that the standard reduction potential `(E^(@))` of `Cr^(3+) | Cr` and `Cr^(2+) |Cr` are -0.74 and -0.91 V respectively. The `E^(@)` of `Cr^(3+) |Cr^(2+)` is:

A

`-0.83V`

B

`+0.4V`

C

`-0.4V`

D

`-0.18V`

Text Solution

Verified by Experts

The correct Answer is:
C
`Cr^(3+)+3e^(-)toCr" "Delta^(@)G_(1)=-3xxF(-0.74)`
`(Cr to Cr^(2+)+2e^(-)" "Delta^(@)G_(2)=-2xxFxx0.91)/(Cr^(3+)+e^(-)to Cr^(2+)" "Delta^(@)G_(3)=Delta_(@)G_(1)+Delta^(@)G_(2))`
`Delta^(@)G_(3)=Delta^(@)G_(1)+Delta^(@)G_(2)`
`-nE_(3)^(@)F=2.22F+(-1.82F)," "E_(3)^(@)=-0.4V`
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