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NEET 2022, Chemistry Q14: Electrochemical Cell And Nernst Equation

NEET2022Chemistry
Q.

At 298 K, the standard electrode potentials of Cu/Cu, Zn/Zn, Fe/Fe and Ag/Ag are 0.34 V, -0.76 V, -0.44 V and 0.80 V, respectively.

On the basis of standard electrode potential, predict which of the following reaction can not occur ?

  1. A

    CuSO(aq) + Fe(s) FeSO(aq) + Cu(s)

  2. B

    FeSO(aq) + Zn(s) ZnSO(aq) + Fe(s)

  3. C

    2CuSO(aq) + 2Ag(s) 2Cu(s) + AgSO(aq)

  4. D

    CuSO(aq) + Zn(s) ZnSO(aq) + Cu(s)

Solution

From the standard reduction potentials, the activity (reducing power) order of the metals is Zn Fe Cu Ag.

A displacement reaction proceeds only when a more reactive metal displaces a less reactive one from its salt.

Option (3) asks silver to displace copper from CuSO, but silver is less reactive than copper, so this reaction cannot occur.

The other three reactions are feasible (Fe displaces Cu, Zn displaces Fe, and Zn displaces Cu).

Concept behind this question

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