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A button cell used in watches functions ...

A button cell used in watches functions as following
`Zn(s)+Ag_(2)O(s)+H_(2)O(l) iff 2Ag(s)+Zn^(2+)(aq)+2OH^(-)(aq)`
If half-cell potential are
`Zn^(2+)(aq)+2e^(-) to Zn(s), E^(@)=-0.76V`
`Ag_(2)O(s)+H_(2)O(l)+2e^(-) to 2Ag(s)+2OH^(-)(aq),E^(@)=0.34V`
The cell potential will be

A

1.10V

B

0.42V

C

0.84V

D

1.3V

Text Solution

Verified by Experts

The correct Answer is:
A
For hy drogen electrode , reduction reaction is
`H^(+)+e=(1)/(2)H_(2)`
`E_(H^(+)//(1)/(2)H_(2))^(@)=E_(H^(+)//(1)/(2)H_(2))^(@)-(0.059)/(n)"log"(p^(1//2)H_(2))/([H^(+)])`
`=0-(0.059)/(n)"log"(1)/(10^(-10))=0.0591`
[pH=10means `|H^(+)| =10^(-1)M`]
`therefore` Oxidation potential `=0.591V`.
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