Copper Purification Circuit Setup

The purification of metals using electrolysis is a common technique, especially for metals like copper. This process is called electrolytic refining. To set up a circuit for the purification of copper, specific components are needed for the electrolytic cell: an anode, a cathode, and an electrolyte solution.

Understanding Electrolytic Refining of Copper

In electrolytic refining:

• The anode is made from the impure metal that needs to be purified. In this case, it should be impure copper. At the anode, the metal atoms lose electrons (oxidation) and dissolve into the solution as positive ions (e.g., Cu → Cu²⁺ + 2e^-).
• The cathode is made from a thin strip of the pure metal. Here, it should be pure copper. At the cathode, the positive metal ions from the solution gain electrons (reduction) and deposit onto the cathode as pure metal (e.g., Cu²⁺ + 2e^- → Cu).
• The electrolyte solution must contain ions of the metal being purified. For copper purification, a solution of copper sulfate (CuSO₄) is typically used, as it provides Cu²⁺ ions necessary for the process.

The main goal is to dissolve the impure copper at the anode and deposit pure copper at the cathode, leaving impurities behind or collecting them as anode sludge.

Analyzing the Electrode and Solution Options

Let's examine the given options based on the principles of electrolytic refining:

• Option 1: Anode—Impure copper; Cathode—Pure copper; Solution—Water
  This is incorrect because water does not contain dissolved copper ions (Cu²⁺) needed to act as an electrolyte for depositing copper at the cathode.
• Option 2: Anode—Carbon; Cathode—Pure copper; Solution—Copper sulphate
  This is incorrect. While the cathode and solution are suitable, the anode should be made of the impure metal (impure copper) to allow it to dissolve. Carbon is often used as an inert electrode in other electrolytic processes but not for dissolving the metal to be purified in this manner.
• Option 3: Anode—Impure copper; Cathode—Pure copper; Solution—Copper sulphate
  This option correctly identifies all the necessary components. The impure copper anode dissolves, and pure copper deposits onto the pure copper cathode from the copper sulfate solution.
• Option 4: Anode—Pure copper; Cathode—Impure copper; Solution—Copper sulphate
  This is incorrect. The roles of the anode and cathode are reversed. The impure copper should be the anode (to dissolve) and the pure copper should be the cathode (to receive the deposited pure metal). If pure copper were the anode, it would dissolve instead of the impure metal.

Conclusion on Circuit Setup

Based on the principles of electrolytic refining, the correct setup for the purification of copper requires an anode made of impure copper, a cathode made of pure copper, and an electrolyte solution of copper sulfate.