Tollen reagent is used for the detection of aldehydes. When a solution of `AgNO_(3)` is added to glucose with `NH_(4)OH`, then gluconic acid is formed.
`Ag^(o+)+e^(-) rarr Ag," "E^(c-)._(red)=0.8V`
`C_(6)H_(12)O_(6)rarr underset(Gluconic aci d)(C_(6)H_(12)O_(7)+)2H^(o+)+2e^(-) , " "E^(c-)._(o x i d ) =-0.05V`
`[Ag(NH_(3))_(2)]^(o+)+e^(-) rarr Ag(s)+2NH_(3), " "E^(c-)._(red)=0.337V`
`[Use2.303xx(RT)/(F)=0.0592` and `(F)/(RT)=38.92at 298 K ]`
When ammonia is added to the solution, `pH` is raised to `11`. Which half cell reaction is affected by `pH` and by how much ?

Options

A. `E_(o x i d )` will increase by a factor of `0.65 ` from `E^(c-)._(o x i d)`.
B. `E_(o x i d )` will decrease by a factor of `0.65 ` from `E^(c-)._(o x i d)`.
C. `E_(red )` will increase by a factor of `0.65 ` from `E^(c-)._(red)`.
D. `E_(red )` will decrease by a factor of `0.65 ` from `E^(c-)._(red)`.

Answer

c

Explanation

On increasing the concentration of `NH_(3)`, the concentration of `H^(o+)` ion decreases, therefore
`E_(red)=E^(c-)._(cell)-(0.0592)/(n)log[H^(o+)]^(2)`
`=0-(0.0592)/(2)xx2log10^(-11)`
`[:'pH=11implies[H^(o+)]=10^(11)M]`
`=+0.0592xx11=0.6512V=0.65V`
`E_(red)` increased by a factor of `0.65` from `E^(c-)._(red)`.