In the electrolytic refining of blister copper, the total number of main impurities, from the following, removed as anode mud is ________. Pb, Sb, Se, Te, Ru, Ag, Au and Pt.
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Anode mud consists of elements located below Copper in the electrochemical series. They are valuable byproducts that often pay for the cost of the refining process itself!
Step 1: Understanding the Concept:
During the electrolytic refining of copper, the impure copper is the anode. Metals that are less basic (less electropositive) than copper do not oxidize and instead settle below the anode as "anode mud." Step 2: Detailed Explanation:
1. More electropositive metals (like $\text{Fe}, \text{Ni}, \text{Zn}$) dissolve in the electrolyte as sulfates.
2. Less electropositive (noble) metals and certain non-metals do not dissolve and form the anode mud.
3. According to standard chemical processing (and NCERT), the common impurities recovered from anode mud in copper refining are:
- Antimony ($\text{Sb}$)
- Selenium ($\text{Se}$)
- Tellurium ($\text{Te}$)
- Silver ($\text{Ag}$)
- Gold ($\text{Au}$)
- Platinum ($\text{Pt}$)
4. Lead ($\text{Pb}$) typically forms insoluble $\text{PbSO}_4$ which precipitates but is usually classified as part of the sludge/residue rather than the specific commercial impurities meant in this context. Ru is a noble metal but is not a "main" impurity typically mentioned for blister copper.
5. Thus, the count of main impurities listed in standard texts is 6 ($\text{Sb, Se, Te, Ag, Au, Pt}$). Step 3: Final Answer:
The total number is 6.
