1. Tardigrade
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  4. For the cell Zn(s) | Zn2+ (aq) || Mx+ (aq) | M(s), different half cells and their standard electrode potentials are given below: Mx+(qa/M(s) Au3+(aq)/Au(s) Ag+(aq)/Ag(s) Fe3+(aq)/Fe2+(aq) Fe2+(aq)/Fe(s) E°Mx+/M(v) 1.40 0.80 0.77 -0.44 If E°Zn2+/Zn = - 0.76 V, which cathode will give a mximum value of E°cell per electron transferred ?

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Q. For the cell $Zn(s) | Zn^{2+} (aq) || M^{x+} (aq) | M(s),$ different half cells and their standard electrode potentials are given below :
$M^{x+}(qa/M(s)$ $Au^{3+}(aq)/Au(s)$ $Ag^{+}(aq)/Ag(s)$ $Fe^{3+}(aq)/Fe^{2+}(aq)$ $Fe^{2+}(aq)/Fe(s)$
$E^{\circ}_{M^{x+}/M^{(v)}}$ 1.40 0.80 0.77 -0.44

If $E^{\circ}_{Zn^{2+}/Zn} = - 0.76 V$, which cathode will give a mximum value of $E^{\circ}_{cell}$ per electron transferred ?

JEE MainJEE Main 2019Electrochemistry

Solution:

We have,
$E _{\text {cell }}^{\circ}= E _{\text {cathode }}^{\circ}- E _{\text {anode }}^{\circ}$
For a high value of $E _{\text {cell }}^{\circ}$ the value of SRP of cathode should be high.
Here the highest value is for $Au ^{3+} / Au$
$E _{\text {cell }}^{\circ}=1.4-(-0.76)=2.16\, V$
Note: Here the transfer of electron in the cell won't affect the $E _{\text {cell }}^{\circ}$ value.