Question

The concentration of potassium ions inside a biological cell is at least 20 times higher than outside. The resulting potential difference across the cell is important in several processes such as transmission of nerve impulses and maintaining the ion balance. A simplel 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` moolar solution of `M^(o+)` is replaced by a `0.0025` molar `M^(o+)` solution, then the magnitude of the cell potential would be
A. 35 m V
B. 70 m V
C. 140 m V
D. 700 m V

Answer 1

Correct Answer - C
From the above quation ,
`(2.303 RT)/(F) "log" (1)/(0.05) = 70 m V = 70 xx 10^(-3) V = 0.07 V `
`therefore (2.303 RT)/(F) = (0.07)/(1.301) = 0.0538` V
For the new concentration ,
`E_(cell) = (2.303 RT)/(F) "log" (1)/(0.0025)`
`= 0.0538 log 400 = 0.0538 xx 2.6021V`
= `0.140 V = 140 m V `