Which from following formulae is used to obtain value of E cell ∗ for a reaction taking place in Dry cell?

Question

Which from following formulae is used to obtain value of E cell ∗ ​ for a reaction taking place in Dry cell?

TestHub · Accepted Answer

The standard Gibbs free energy change for a cell reaction is related to the standard cell potential by the equation:

$Δ G^{\circ} = - n F E_{cell}^{\circ}$

For a dry cell (Leclanché cell), the half-reactions are:
Anode (oxidation): $Z n (s) \to Z n^{2 +} (a q) + 2 e^{-}$
Cathode (reduction): $2 N H_{4}^{+} (a q) + 2 M n O_{2} (s) + 2 e^{-} \to M n_{2} O_{3} (s) + 2 N H_{3} (a q) + H_{2} O (l)$

The overall cell reaction involves the transfer of $2$ moles of electrons, which means $n = 2$ .

Substituting $n = 2$ into the equation, we get:

$Δ G^{\circ} = - 2 F E_{cell}^{\circ}$

Rearranging the formula to solve for $E_{cell}^{\circ}$ gives:

$E_{cell}^{\circ} = \frac{- Δ G ^{\circ}}{2 F}$

Answer: $\frac{- Δ G ^{\circ}}{2 F}$

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