Electrolytic refining of zinc

Introduction
Electrolytic refining is a process used to purify metals obtained from ores. In the case of zinc, electrolytic refining is carried out to obtain high-purity zinc metal.

Explanation
The correct option for the given question is option D, which states that acidified zinc sulphate is the electrolyte. Let's understand why this is the correct answer.

Electrolyte
- In the process of electrolytic refining, an electrolyte is used, which is a solution containing metal ions.
- In the case of zinc, the electrolyte used is acidified zinc sulphate (ZnSO4) solution.
- Acidified zinc sulphate provides zinc ions (Zn2+) required for the electrolytic process.

Graphite at the anode
- An anode is the positive electrode in an electrolytic cell.
- In the electrolytic refining of zinc, graphite is used as the anode.
- Graphite is an inert material that does not react during the electrolysis process.
- It allows the passage of electrons from the anode to the cathode.

Impure metal at the cathode
- A cathode is the negative electrode in an electrolytic cell.
- In the electrolytic refining of zinc, the impure metal is placed at the cathode.
- The impure zinc metal is connected to the negative terminal of the power source.
- During electrolysis, zinc ions (Zn2+) from the electrolyte are reduced and deposited onto the cathode.
- This results in the purification of zinc, as impurities do not get reduced and remain in the electrolyte or settle at the bottom.

Metal ion reduction at the anode
- In the given options, it is mentioned that the metal ion gets reduced at the anode, which is incorrect.
- Reduction occurs at the cathode, where the metal ions gain electrons and are deposited as pure metal.
- At the anode, oxidation occurs, where the anode material loses electrons and forms ions.
- In the case of zinc electrolytic refining, the anode is made of graphite, which does not react or participate in the reduction process.

Therefore, the correct answer is option D, which states that acidified zinc sulphate is the electrolyte used in the electrolytic refining of zinc.