Cell 1 reaction is more spontaneous than cell 2 reaction.
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B
Cell 2 reaction is more spontaneous than cell 1 reaction.
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C
E∘cell1=−0.44V
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D
Both (b) and (c).
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Solution
The correct option is B Cell 2 reaction is more spontaneous than cell 1 reaction. For cell 1: Fe gets oxidised to Fe2+ because it has a lower SRP than H2
At anode: Fe(s)⇌Fe2+(aq)+2e−
At cathode: 2H+(aq)+2e−⇌H2(g)
E∘cell1=SRP of cathode - SRP of anode E∘cell1=E∘H+(aq)/H2(g)−E∘Fe2+(aq)/Fe(s) E∘cell1=0−(−0.44)=+0.44V
Similarly for cell 2: Mg gets oxidised to Mg2+ because it has a lower SRP than H2
At anode: Mg(s)⇌Mg2+(aq)+2e−
At cathode: 2H+(aq)+2e−⇌H2(g)
E∘cell2=SRP of cathode - SRP of anode E∘cell2=E∘H+(aq)/H2(g)−E∘Mg2+(aq)/Mg(s) E∘cell2=0−(−2.37)=+2.37V
Higher the E∘cell value, more is the spontaneity. E∘cell2>E∘cell1
Cell 2 reaction is more spontaneous than cell 1 reaction.
Theory :
The magnitude of the cell potential is the measure of the driving force behind a reaction. The larger the value of the cell potential,the farther is the reaction
from equilibrium.