1.

E_(Fe^(3+)//Fe^(+2))^(0)=+0.77V,E_(Fe^(+3)//Fe)^(0)=0.036V . What is E_(Fe//Fe^(+2))^(0) and is Fe^(+2)stable to disproportionation in aqueous solution under standard conditions

Answer»

`+0.44 V,` yes
`-0.44V`, No
`+0.44 V`, No
`-0.44 V`, yes

Solution :`Fe^(3+)+e^(-)rarr Fe^(2+)""(1)E_(1)^(@)=0.77V" "DeltaG_(1)^(@)=-1xxFxx0.77`
`Fe^(3+)+3e^(-)rarrFe""(2)E_(2)^(@)=-0.036V""DeltaG_(2)^(@)=3xxFxx0.036`
`FerarrFe^(2+)+2e^(-)""(3)E_(3)=DeltaG_(3)^(@)=-2xxFxxE_(3)^(@)`
`(1)-(2)=3`
`DeltaG_(1)^(@)-DeltaG_(2)^(@)=DeltaG_(3)^(@)`
`rArr-Fxx0.77-3F-0.036=-2xFxxE_(3)^(@)" "rArr(0.77xx0.108)=2xxE_(3)^(@)""rArrE_(3)^(@)~=0.44V Ans.`
Disproportionation reaction.
`3FE^(2+)rarrFe+2Fe^(3+)""(4)`
`Fe^(2+)+2e^(-) rarr Fe`
`E^(@)=-0.44V""DeltaG^(@)=-2xxFxx(-0.44)(5)`
`Fe^(2+)rarr Fe^(3+)+e^(-)`
`E^(@)=-0.77V""DeltaG^(@)=-1xxFxx(0.77)=+ve""(6)`
`:'DeltaG_(4)^(@)=-2xxFxx(0.44)+2(-1xxFxx(-0.77))=+ve`
`:' DeltaG_(4)^(@) GT 0,""rArr` Reaction is not SPONTANEOUS.
HENCE, `Fe^(2+)` is stable to disproportiionation.


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