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Calculate the emf of the following call ...

Calculate the emf of the following call at 298 K :
`2Cr(s)+3Fe^(2+)(0.1M)rarr2Cr^(3+)(0.01M)+3Fe(s)`
`["Given : "E_((Cr^(3+)|Cr))^(@)=-0.74V, E_((Fe^(2+)|Fe))^(@)=-0.44V]`

Text Solution

Verified by Experts

`E_("cell")^(@)=E_("cathode")^(@)-E_("anode")^(@)=E_(Fe^(2+)|Fe)^(@)-E_(Cr^(3+)|Cr)`
`=[-0.44-(0.74)]V=0.30V`
Applying Nernst's equation to the cell reaction, we get
`E_("cell")=E_("cell")^(@)-(0.059)/(3)log.([Cr^(3+)]^(2))/([Fe^(2+)]^(3))`
`=0.30-(0.059)/(3)log.((0.01)^(2))/((0.1)^(3))=0.319V`
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Knowledge Check

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