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The emf of the following three galvanic ...

The emf of the following three galvanic cells :`1. Zn//Zn^(2+) ( 1M) || Cu^(2+) (1 M) //Cu`
`2. Zn//ZN^(2+ ) (1 M)|| Cu^(2+) //cu
`3. Zn//Zn^(2+) (1 M) || Cu^(2+) (0.1 M) Cu`
are repersented by `E_1, E_2, E_3` which of the following statement is true ?

A

`E_(1) gt E_(2) gt E_(3)`

B

`E_(3) gt E_(2) gt E_(1)`

C

`E_(3) gt E_(1) gt E_(2)`

D

`E_(2) gt E_(1) gt E_(3)`.

Text Solution

Verified by Experts

The correct Answer is:
D
(d) According to Nernst equation
`E_(cell)=E_(cell)^(@)-(0.0591)/(n)"log"([Zn^(2+)])/([Cu^(2+)])`
In first case :`([Zn^(2+)])/([Cu^(2+)])=1`
`:. E_(cell)(E_(1))=E_(cell)^(@)`
In third case , `([Zn^(2+)])/([Cu^(2+)])=((1M))/((0.1 M))=10`
`E_(cell)(E_(3))=E_(cell)^(@)-(0.0591)/(2)`
`=E_(cell)^(@)-0.02955`
Thus,`E_(2) gt E_(1) gt E_(3)`.
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