Question

When an aqueous solution of $AgN{O}_3$ is electrolysed between platinum electrodes, the substances liberated at anode and cathode are:

• A. Silver is deposited at cathode and $O_2$ is liberated at anode
• B. Silver is deposited at cathode and $H_2$ is liberated at anode
• C. Hydrogen is liberated at cathode and $O_2$ is liberated at anode
• D. Silver is deposited at cathode and Pt is dissolved in electrolyte

Answer 1

Answer: (A)

Silver is deposited at cathode and $O_2$ is liberated at anode

At cathode:

The reaction with a higher value of $E^0$ takes place at the cathode. Therefore, deposition of silver will take place at the cathode.

$A{g}_{\left(aq\right)}^{+}+e^{-}\to A{g}_{\left(s\right)};E^0-0.80V$

At anode:

Since Pt electrodes are inert, the anode is not attacked by NO3- ions. Therefore, OH - or NO3- ions can be oxidized at the anode. But OH - ions having a lower discharge potential and get preference and decompose to liberate O2.

$O{H}^{-}\to OH+e^{-}$
$4O{H}^{-}\to 2H_{2}O+O_2$

Hence option (A) is correct