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Question: Answered & Verified by Expert

At 298 K, the standard electrode potentials of Cu2+/Cu, Zn2+/Zn, Fe2+/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 cannot occur?

ChemistryElectrochemistryNEETNEET 2022 (Phase 1)
Options:
  • A CuSO4(aq)+Fe(s)FeSO4(aq)+Cu(s)
  • B FeSO4(aq)+Zn(s)ZnSO4(aq)+Fe(s)
  • C 2CuSO4(aq)+2Ag(s)2Cu(s)+Ag2SO4(aq)
  • D CuSO4(aq)+Zn(s)ZnSO4(aq)+Cu(s)
Solution:
1041 Upvotes Verified Answer
The correct answer is: 2CuSO4(aq)+2Ag(s)2Cu(s)+Ag2SO4(aq)

The given standard reduction potentials of Zn, Cu, Ag and Fe are;

E°Zn2+Zn=-0.76 V, E°Cu2+cu=0.34 VE°Ag+Ag=0.80 V, and E°Fe2+Fe=-0.44 V 

The condition for reaction to occur, E°Cell=E°SRPreduction reaction-E°SRPoxidation reaction must have the positive value.

A Cu2+aq+FeCu +Fe2+aq

E°Cell=0.34+0.44E°Cell=0.78 V

B Zn +Fe2+aqZn2+aq+Fe

E°Cell=-0.44+0.76E°Cell=+0.32 V

C Cu2+aq+2Ag2Ag+aq+Cu

E°Cell=0.34-0.80E°Cell=-0.46 V

D Zn+Cu2+aqZn2+aq+Cu

E°Cell=0.34+0.76E°Cell=+1.10 V

Hence, the reaction given in C option is not possible.

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