QJEEM19Ch9464: JEE Main 2019 Chemistry - Class 12 JEEM19Ch9464 Solution: Calculate the standard cell potential in (V) of the cell in…

Standard emf,

${E^0} = E_{A{g^ + }|Ag}^0 - E_{F{e^{3 + }}|F{e^{2 + }}}^0$ ..............(1)

Given $E_{Fe^{2+ }/Fe}^o = yV$

$\therefore$ Fe²⁺ + 2e^- $\to$ Fe ..........(2)

${E^0}$ = y and $\Delta {G^0}$ = -2Fy

Also given $E_{Fe^{3+ }/Fe}^o = zV$

$\therefore$ Fe³⁺ + 3e^- $\to$ Fe .........(3)

${E^0}$ = z and $\Delta {G^0}$ = -3Fz

Performing (2) - (1), we get

Fe³⁺ + e^- $\to$ Fe²⁺

$\therefore$ $\Delta {G^0}$ = -3Fz + 2Fy

$\Rightarrow$ -(1)F ${E^0}$ = -3Fz + 2Fy

$\therefore$ $E_{F{e^{3 + }}|F{e^{2 + }}}^0$ = 3z - 2y

From Equation (1),

${E^0} = E_{A{g^ + }|Ag}^0 - E_{F{e^{3 + }}|F{e^{2 + }}}^0$

= x - (3z - 2y) = x + 2y - 3z