Question

What is liberated at the cathode? Explain.

Answer 1

Hint: This question is based on the concept of electrolysis. Electrolysis is a technique that uses direct electric current to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell.

Complete Step By Step Answer:
The example of electrolysis is that the salt-containing water can be decomposed by passing electric current to their original elements hydrogen and oxygen. Further, Molten sodium chloride can be decomposed to sodium and chlorine atoms.
In the process of electrolysis, there is an interchange of ions and atoms due to the addition or removal of electrons from the external circuit. Basically, on passing current, cations move to the cathode, take electrons from the cathode (given by the supply source-battery), and are discharged into the neutral atom. The neutral atom, if solid, is deposited on the cathode and if gas, moves upwards. This is a reduction process and the cation is reduced at the cathode. At the same time anions give up their extra electrons to the anode and are oxidized to neutral atoms at the anode. Electrons released by the anions travel across the electrical circuit and reach the cathode completing the circuit. Electrolysis involves a simultaneous oxidation reaction at anode and a reduction reaction at the cathode.
So, according to this concept, copper from impure copper plates (anode) will get dissolved in the copper sulphate solution as $ C{u^{2 + }} $ ions, making the anode plate thinner. On the other hand, $ C{u^{2 + }} $ ions, present in the solution, get reduced at the thin pure copper plate (cathode) and deposited as pure copper, making it thicker. Hence, the final answer is that the pure copper is liberated at cathode.

Note:
It is important to note that Cations get attracted towards the negatively charged electrode in electrolysis while Anions get attracted towards the positively charged electrode in electrolysis. Cations gain electrons and convert into neutral atoms or molecules while Anions generally lose electrons and convert into neutral atoms or molecules.