A metal extracted by any method is usually contaminated with some impurity. For obtaining metals of high purity, several techniques are used depending upon the differences in properties of the metal and the impurity. Some of them are listed below:

(a) Distillation

(b) Liquation

(c) Electrolysis

(d) Zone refining

(e) Vapour phase refining

(f) Chromatographic methods

Which of the following is an electrolyte used during the electrolytic refining of copper?

Copper sulphate solution acidified with sulphuric acid

The correct answer is option 2. Copper sulphate solution acidified with sulphuric acid.

The electrolyte used during the electrolytic refining of copper is copper sulphate solution acidified with sulphuric acid.

In the electrolytic refining process of copper, the goal is to purify copper to a high degree of purity, suitable for electrical applications. Here's how the process works:

Electrolyte Composition: The electrolyte is typically an aqueous solution of copper(II) sulfate \((CuSO_4)\) mixed with sulfuric acid \((H_2SO_4)\). The addition of sulfuric acid helps to increase the conductivity of the solution and ensures that the copper ions remain in solution.

Anode and Cathode:

• Anode: The impure copper (blister copper) is used as the anode.
• Cathode: A pure copper sheet is used as the cathode.

Electrolytic Cell Operation:

When an electric current is passed through the electrolyte, copper from the impure copper anode dissolves into the solution as Cu²⁺ ions.

These copper ions then migrate to the cathode, where they gain electrons (reduction) and deposit as pure copper.

Impurities Handling: Impurities in the anode either fall to the bottom of the cell as anode sludge or remain in solution. Precious metals like silver and gold, which are often present as impurities, do not dissolve and can be recovered from the anode sludge.

So, the correct answer to the question of which electrolyte is used during the electrolytic refining of copper is 2.Copper sulphate solution acidified with sulphuric acid