Q.
Tollen's reagent is used for the detection of aldehyde when a solution of $AgNO _{3}$ is added to glucose with $NH _{4} OH$ then gluconic acid is formed
$ Ag ^{+}+e^{-} \rightarrow Ag ; E_{ red }^{+}=0.8 \,V$
$ C _{6} H _{12} O _{6}+ H _{2} O \rightarrow $ Gluconic acid $\left( C _{6} H _{12} O _{7}\right)+2 H ^{+}+2 e^{-} $
$E_{ red }{ }^{\circ}=-0.05 \,V $
$ Ag \left( NH _{3}\right)_{2}{ }^{+}+e^{-} \rightarrow Ag ( s )+2 NH _{3} ; E_{ red }{ }^{\circ}=0.337 \,V$
[Use $2.303 \times \frac{R T}{F}=0.0592$ and $ \frac{F}{R T}=38.92$ at $398\, K ]$
When ammonia is added to the solution, $pH$ is raised to $11$ . Which half- cell reaction is affected by $pH$ and by how much?
JEE AdvancedJEE Advanced 2006
Solution: