Question

Tollen's reagent is used for the detection of aldehydes. When a solution of $AgN{O}_3$ is added to glucose with $N{H}_{4}OH$, then gluconic acid is formed.
$A{g}^{+}+e^{-}\to Ag;E_{red}^o=0.80V$
$C_6{H}_{12}{O}_6+H_{2}O\to C_6{H}_{12}{O}_7+2H^{+}+2e^{-};E_{oxi}^o=-0.05V$
$Ag(N{H}_3{)}_2^{+}+e^{-}\to Ag(s)+2N{H}_3;E_{red}^o=0.337V$

Find $\log K$ of the reaction?
$2A{g}^{+}+C_6{H}_{12}{O}_6+H_{2}O\to 2Ag\left(s\right)+C_6{H}_{12}{O}_7+2H^{+}$
$(\text{Take}:2.303\times \frac{RT}{F}=0.06\text{at}298K)$

• A. 57.58
• B. 25
• C. 28.5
• D. 46.25

Answer 1

The correct option is B 25

$A{g}^{+}+e^{-}\to Ag...\left(1\right);E_{red}^o=0.80V$
$C_6{H}_{12}{O}_6+H_{2}O\to C_6{H}_{12}{O}_7+2H^{+}+2e^{-}...\left(2\right);E_{oxi}^o=-0.05V$
On adding $\left(1\right)\text{and}\left(2\right)$
$2A{g}^{+}+C_6{H}_{12}{O}_6+H_{2}O\to 2Ag\left(s\right)+C_6{H}_{12}{O}_7+2H^{+};E^o=0.75V$
At equilibrium;
$E^o=\frac{0.06}{2}\log K$
$\log K=\frac{2E^o}{0.06}=\frac{2\times 0.75}{0.06}=25$