Question

State one relevant observation for the following:

At the anode when aqueous copper sulfate solution is electrolyzed using copper electrodes.

Answer 1

Electrolysis of aqueous Copper sulfate using copper electrodes

• Electrolysis is a process in which an electrolyte, in this example copper sulfate solution $\left({\mathrm{CuSO}}_4\right)$ (concentrated sulfuric acid $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ is also added to increase the conductivity), performs redox reactions at the electrodes under the influence of an electric current.
• When the current passes through the electrolyte, ${\mathrm{Cu}}^{2+}$and ${\mathrm{H}}^{+}$ ions migrate towards the cathode, and ${{\mathrm{SO}}_4}^{2-}$and ${\mathrm{OH}}^{-}$ ions migrate towards the anode.

Reaction at the anode:

• Both Sulfate $\left({{\mathrm{SO}}_4}^{2-}\right)$ and Hydroxyl $\left({\mathrm{OH}}^{-}\right)$ ions migrate towards the anode, but neither of them is discharged due to the active nature of the anode.
• Since the anode is of copper, it loses 2 electrons and forms copper ions.
• The number of Copper ions furnished by the anode is equal to the number of copper ions discharged at the cathode.
• The chemical reaction is as follows

$\mathrm{Cu}\left(\mathrm{s}\right)-2{\mathrm{e}}^{-}\to {\mathrm{Cu}}^{2+}\left(\mathrm{aq}\right)$

At the anode, copper atoms produce copper ions and travel toward the cathode. As a result after some time, nothing is left at the anode.