A simple model for a concentration cell involving a metal `M` is
`M(s)|M^(o+)(aq,0.05 ` molar`)||M^(o+)(aq,1` molar`)|M(s)`
For the abov electrolytic cell, the magnitude of the cell potential is `|E_(cell)|=70mV.`
If the `0.05` molar solution of `M^(o+)` is replaced by a `0.0025` molar `M^(o+)` solution, then the magnitude of the cell potential would be
(a)`35mV`
(b)`70mV`
(c)`140mV`
(d)`700mV`

Options

A. `35mV`
B. `70mV`
C. `140mV`
D. `700mV`

Answer

C

Explanation

`E_(cell)=(-0.0591)/(a)log{(0.0025)/(11)}=-(0.0591)/(1)log{(0.05)/(20)}`
`=70mV+(0.0591)/(1)log20=140mV`