What happens to the impurities during the electrolytic refining of copper?
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A.
They dissolve in the electrolyte.
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B.
They settle as anode mud.
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C.
They evaporate as gas.
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D.
They deposit on the cathode.
Correct Answer:
B. They settle as anode mud.
Explanation:
During the electrolytic refining of copper, the process effectively separates pure metal from various contaminants through electrochemical reactions. The anode is composed of impure copper, while the cathode consists of high-purity copper or stainless steel, all submerged in an acidic copper sulfate electrolyte.
As electric current passes through the system, copper atoms at the anode oxidize and dissolve into the solution as ions. Concurrently, impurities are managed based on their chemical reactivity: - Soluble Impurities: More reactive metals, such as iron, zinc, and nickel, dissolve into the electrolyte along with the copper but remain in the solution because they are more difficult to reduce than copper at the cathode.
- Insoluble Impurities: Less reactive noble metals, including gold, silver, and platinum, do not dissolve at the anode. Instead, they detach as the copper around them dissolves and settle at the base of the electrolytic cell. This residue is known as anode mud or anode slime.Because these insoluble impurities are recovered from the bottom of the tank rather than dissolving or depositing on the cathode, the correct answer is that they settle as anode mud.
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