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EMF

The standard ...

Question

The standard oxidation potentials, $E^{\circ}$ , for the half reactions are as,
$Z n \to Z n^{2 +} + 2 e^{-}; E^{\circ} = + 0.76 v o l t$
$F e \to F e^{2 +} + 2 e^{-}; E^{\circ} = + 0.41 v o l t$
The emf of the cell, $F e^{2 +} + Z n \to Z n^{2 +} + F e$ is:

A

+ 0.35 v o l t

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B

- 0.35 v o l t

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C

+ 1.17 v o l t

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D

- 1.17 v o l t

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Solution

The correct option is A $+ 0.35 v o l t$
$E_{c e l l}$ or $E M F$ = $E_{c a t h o d e}^{o} - E_{a n o d e}^{o}$
since, oxidation potentials are given so for converting them into reduction potential just reverse the sign.
$E^{o} Z n^{2 +} / Z n = - 0.762$
$E^{o} F e^{2 +} / F e = - 0.41$
$E M F = E_{c a t h o d e}^{o} - E_{a n o d e}^{o}$
$E M F = E_{F e / F e^{2 +}}^{o} - E_{Z n / Z n^{+ 2}}^{o}$
$= - 0.41 - (- 0.762)$
$= - 0.41 + 0.76$
$E M F = + 0.35 V$

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Similar questions

Q. The standard oxidation potentials

E^{o}

, for the half cell reactions are given as

Z n \to Z n^{2 +} + 2 e^{-}, E^{\circ} = + 0.76 V F e \to F e^{2 +} + 2 e^{-}, E^{\circ} = + 0.41 V

The EMF for the cell reaction,

F e^{2 +} + Z n \to Z n^{2 +} + F e

Q. The standard reduction potentials

E^{⊝}

for the half reactions are follows :

Z n \to Z n^{2 +} + 2 e^{-}; E^{⊝} = + 0.76 V

F e \to F e^{2 +} + 2 e^{-}; E^{⊝} = 0.41 V

The EMF for the cell reaction

F e^{2 +} Z n \to Z n^{2 +} + F e

The standard reduction potentials, $E^{\circ}$ , for the half-reactions are as $Z n = Z n^{2 +} + 2 e$ , $E^{\circ}$ = + 0.76 V and $F e = F e^{2 +} + 2 e$ , $E^{\circ}$ = + 0.41 V. The e.m.f. for the cell reaction, $F e^{2 +} + Z n = Z n^{2 +} + F e$ is

Q. The standard electrode potential of the half cells is given below:

Z n^{2 +} + 2 e^{-} \to Z n; E = - 0.76 V

F e^{2 +} + 2 e^{-} \to F e; E = - 0.44 V

The emf of the cell

F e^{2 +} = Z n^{-} \to Z n^{2 +} + F e

Q. Given the standard half-cell potentials

(E^{o})

of the following as

Z n = Z n^{2 +} + 2 e^{-}

E^{o} = + 0.76

V

F e = F e^{2 +} + 2 e^{-}

E^{o} = + 0.41

V

Then the standard e.m.f. of the cell with the reaction

F e^{2 +} + Z n \to Z n^{2 +} + F e

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