Question

Copper can be extracted by hydro-metallurgy but not zinc, Explain.

Answer 1

Hint: The reduction potential is described as the ability of a chemical compound to get itself reduced by accepting electrons. The element with lower reduction potential value displaces the element with higher reduction potential value.

Complete step by step answer:
Hydrometallurgy is the process used for extraction of useful metals from their respective ores. The metals are extracted by forming the aqueous solution of the salt of the given metal and then extracting
the specific metal from its solution.
The hydrometallurgy method is done on the basis of the principle that the metals with more electropositive value displace the metals with less electropositive value from their respective salt solution.
When iron is added to the aqueous solution of copper sulfate, the precipitate of iron sulfate is formed.
The reaction is shown below.
$CuS{O_4} + Fe \to FeS{O_4} + Cu$
This happens because the reduction potential value of element copper is lower than the reduction potential value of zinc and iron.
Therefore, the copper ion is displaced by the iron ion from its salt solution as shown below.
$Fe(s) + C{u^{2 + }}(aq) \to F{e^{2 + }}(aq) + Cu(s)$
To displace zinc from its salt solution, reactive metals like magnesium, potassium whose reduction potential is lower than zinc are used but these metals are also very reactive towards water and they react by releasing hydrogen gas.
The reaction is shown below.
$2K(s) + 2{H_2}O(l) \to 2KOH(aq) + {H_2}(g)$
Due to this reason, these metals cannot be utilized to extract zinc from its ore.
Therefore, the metal copper can be extracted by hydro-metallurgy but not zinc.

Note:
Hydrometallurgy involves three principle steps. These are leaching, concentrating solution and
purification and last step recovery of metal compounds. The most used agent for the leaching process is
dilute sulfuric acid.