Question

In the button cells widely used in watches and other devices the following reaction takes place:
Zn(s) + Ag2O(s) + H2O(l) $\rightarrow$ Zn2+(aq) + 2Ag(s) + 2OH- (aq)
Determine $\triangle _rG^\ominus$ and $E^\ominus$ for the reaction.

Answer 1

Zn(s)→ Zn2+(aq)+2e- ; $E^\ominus$ = 0.76 V

Ag2O(s)+H2O(l)+2e- → 2Ag(s)+2OH-(aq) ; $E^\ominus$ = 0.344 V

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Zn(s)+ Ag2O(s)+H2O(l)→ Zn2+(aq)+2Ag(s)+2OH-(aq); $E^\ominus$ = 1.104 V

$E^\ominus$= 1.104 V

We know that,

$\triangle_rG^\ominus=-nFE^\ominus$

= - 2 × 96487 × 1.04

= - 213043.296 J

= - 213.04 kJ