4. Name an ore of zinc other than zinc oxide. By what process can this ore be
Name the anode and cathode used in the electrolytic refining of copper.
Why should metal sulphides and carbonates be converted to metal oxides in
Answers
Explanation:
Answer:
The reduction potentials of zinc and iron are lower than that of copper.
In hydrometallurgy, zinc and iron can be used to displace copper from their solution.
Fe(s) + Cu2+ (aq) → Fe2+ (aq) + Cu(s)
But to displace zinc, more reactive metals i.e., metals having lower reduction potentials than zinc such as Mg, Ca, K, etc. are required.
But all these metals react with water with the evolution of H2 gas.
2K(s) + 2H2O (l) → 2KOH (aq) + H2 (g)
As a result, these metals cannot be used in hydrometallurgy to extract zinc.
Hence, copper can be extracted by hydrometallurgy but not zinc.
Question 6.2.
What is the role of depressant in froth floatation process?
Answer:
In the froth floatation process, the role of the depressants is to separate two sulphide ores by selectively preventing one ore from forming froth.
For example, to separate two sulphide ores (ZnS and PbS), NaCN is used as a depressant which selectively allows PbS