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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^(o+)+e^(-) rarr Ag(s)," "E^(c-)._(red)=0.8V`
`ii. C_(6)H_(12)O_(6)rarr C_(6)H_(12)O_(7)+2H^(o+)+2e^(-), " "E_(o x i d)=-0.05V`
Hence, for reaction
`2Ag^(o+)+C_(6)H_(12)O_(6)+H_(2)Orarr 2Ag(s)+C_(6)H_(12)O_(7)+2H^(o+)`
`E^(c-)._(cell)=0.8-0.05`
`=0.75V`
`E_(cell)=E^(c-)._(cell)-(2.303)/(nF)log K`
At equilibrium, `E_(cell)=0`
`:. E^(c-)._(cell)=(2.303RT)/(nF)log K`
`0.75=(0.0592)/(2) log K`
`log K =(2xx0.75)/(0.0592)=25.33`
or `ln K =2.303xxlogk`
`=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 ?

Knowledge Check

  • 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 ?

    A
    `NH_(3)` combines with `Ag^(o+)` to form a complex.
    B
    `[Ag(NH_(3))_(2)]^(o+)` is a stronger oxidizing reagent than `Ag^(o+)`
    C
    In the absence of `NH_(3)`, a silver salt of gluconic acid is formed.
    D
    `NH_(3)` has affected the standard reduction potential of glucose `//` gluconic acid electrode.

  • 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 ?

    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)`.

  • Tollens reagent is used for the detection of aldehyde when a solution of AgNO_3 is added to glucose With NH_4OH then gluconic acid is formed Ag^(+) +e^(-) to Ag, E_(red) ^(@)=0.8V C_(6)H_(12)O_(6)+H_(2)O to Gluconic aicd(C_(6)H_(12)O_(7))+2H^(+)+2e^(-), E_(oxd)^(@)=-0.05V Ag(NH_(3))_(2)^(+) +e^(-) to Ag(s)+2NH_(3), E_(red)^(@)=0.337V Use 2.303 xx (RT)/(F)=0.0592 and F/(RT)=38.92 at 298K] 2Ag^(+)+C_(6)H_(12)O_(6)+H_(2)O to 2Ag(s)+C_(6)H_(12)O_(7)+2H^(+) Find in K of this reaction.

    A
    66.13
    B
    58.38
    C
    28.3
    D
    46.29