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Tollen reagent is used for the detection...

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 ]`
`2Ag^(o+)+C_(6)H^(12)O_(6)+H_(2)O rarr 2Ag^(s)+C_(6)H_(12)O_(7)+2H^(o+)` Find `lnK` of this reaction.

A

66.13

B

58.38

C

`28.30`

D

46.29

Text Solution

Verified by Experts

The correct Answer is:
B
Cell reaction
(i) `Ag^(+)+e^(-)toAg(s),E_(red)^(o)=0.8V`
(ii) `C_(6)H_(12)O_(6)+H_(2)OtoC_(6)H_(12)O_(7)+2H^(+)+2e^(-),E_("oxid")=-0.05V` ltBrgt Hence, for reaction
`2Ag^(+)+C_(6)H_(12)O_(6)+H_(2)Oto2Ag_((s))+C_(6)H_(12)O_(7)+2H^(+)`
`E_(cell)^(o)=(0.8-0.05)`
`=0.75V`
`E_(cell)^(o)=E_("anode")^(o)-E_("cathode")^(o)`
`=[-0.05-(-0.8)]V`
on the basis of oxidised electrode potential
`=0.75V` By nernst equation
`E_(cell)=E_(cell)^(o)=(2.303RT)/(nF)log_(10)K`
At equilibrium `E_(cell)=0`
`thereforeE_(Cell)^(o)=(2.303RT)/(2)log_(10)K`
`0.75=(0.0592)/(2)log_(10)K) `
`log_(10)K=(2xx0.75)/(0.0592)=25.33`
or In `K=2.303xxlog_(10)K`
`=2.303xx25.33=58.35`.
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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 ] Ammonia is always added in this reaction. Which of the followijng must be wrong ?

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 ?