In the button cell widely used in watches and other devices the following reaction takes place :

$Z n (s) + A g_{2} O (s) + H_{2} O (l) \to Z n^{2 +} (a q) + 2 A g (s) + 2 O H^{-} (a q) D e t e r m i n e Δ_{r} G^{\circ} a n d E^{\circ} f o r t h e r e a c t i o n . [G i v e n, E_{\frac{Z n}{Z n^{2 +}}}^{\circ} = - 0.76 V a n d E_{\frac{A g^{+}}{A g}}^{\circ} + 0.34 V]$

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Solution

$[G i v e n, Z n \to Z n^{2 +} + 2 e^{-}, E^{\circ} = - 0.76 V A g_{2} O + H_{2} O + 2 e^{-} \to 2 A g + 2 O H^{-}; E^{\circ} = (0.80 - 0.45) V]$
In the given electrochemical cell, zinc is oxidised and silver ions are reduced.
$E_{c e l l}^{\circ} = E_{c a t h o d e}^{\circ} - E_{a n o d e}^{\circ} = [0.35 - (- 0.76)] = 1.11 V R e a c t i o n s : A t a n o d e : Z n (s) \to Z n^{2 +} (a q) + 2 e^{-} A t c a t h o d e : A g_{2} O (s) + H_{2} O (l) + 2 e^{-} \to 2 A g (s) + 2 O H^{-} (a q) Δ_{r} G^{\circ} = - n F E^{\circ} = - 2 \times (96500 C) \times (1.11 V) = - 214230 C V (o r J) o r - 2.1423 \times 10^{5} J$
$E^{\circ} = 1.11 V;$
$Δ_{r} G^{\circ} = - 2.1423 \times 10^{5} J$

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Similar questions

Z n (s) + A g_{2} O (s) + H_{2} O (l) \to Z n^{2 +} (a q) + 2 A g (s) + 2 O H^{-} (a q)

Δ_{r} G^{θ}

E^{θ}

In the button cells widely used in watches and other devices the following reaction takes place:

Zn(s) + Ag₂O(s) + H₂O(l) → Zn²⁺(aq) + 2Ag(s) + 2OH⁻(aq)

Determine and for the reaction.

Z n (s) + A g_{2} O (s) + H_{2} O (l) \to Z N^{2 +} (a q) + 2 (A g (s) + 2 O H^{-} (a q)

E^{o}

Δ G^{o}

E_{A g^{+} / A g}^{o} = + 0.80 V, E_{Z n^{2 +} / Z n}^{o} = - 0.76 V)

Z n (s) + A g_{2} O (s) + H_{2} O (l) ⇌ 2 A g (s) + Z n^{2 +} (a q) + 2 O H^{-} (a q)

Z n^{2 +} (a q) + 2 e^{-} \to Z n (s); E^{\circ} = - 0.76 V

A g_{2} O (s) + H_{2} O (l) + 2 e^{-} \to 2 A g (s) + 2 O H^{-} (a q), E^{\circ} = 0.34 V

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