Question

Calculate the standard cell potential in(V) of the cell in which following reaction takes place :
$F{e}^{2+}\left(aq\right)+A{g}^{+}\left(aq\right)\to F{e}^{3+}\left(aq\right)+Ag\left(s\right)$
Given that
$E_{A{g}^{+}}^{\circ }{/}_{Ag}=xV$
$E_{F{e}^{2+}}^{\circ }{/}_{Fe}=yV$
$E_{F{e}^{3+}}^{\circ }{/}_{Fe}=zV$

• A. x + 2y - 3z
• B. x - z
• C. x - y
• D. x + y - z

Answer 1

Answer: (A)

Given:
$E_{A{g}^{\prime }/Ag}^0=x----\left(1\right)$
$E_{F{e}^{2+}/Fe}^0=y----\left(2\right)$
$E_{F{e}^{2+}/Fe}^0=z----\left(3\right)$
Using equation:
$\Delta G^0=-nF{E}^0$
$\Delta G_1^0=-fx$
$\Delta G_2^0=-2Fy$
$\Delta G_3^0=-3Fz$
$F{e}^{2+}2e^{-}\to Fe-2Fy$
$F{e}_{{}_{-}}^{3+}+3e_{{}_{-}}^{-}\to F{e}_{{}_{-}}-3F_{{}_{+}}z$
$F{e}^{2+}\to F{e}^{3+}+e^{-}\left(-2Fy+3Fz\right)$
$A{g}^{+}+e^{-}\to Ag-Fx$
$\Delta G_{Total}=-2Fy+3Fz-Fx=-F{E}_{Cell}^0$
$E_{Cell}^0=x+2y-3z$