Question

Copper can be extracted by hydrometallurgy but not zinc. Explain.

Answer 1

In case of hydrometallurgy, iron and zinc can be used for displacing copper from the solution.

But in case of displacing of zinc, metals with more reactivity (Mg, Ca) are required.

As these metals react with the water and evolve hydrogen gas, it cannot be used in hydrometallurgy to extract zinc.

Answer 2

Answer:

Copper has a higher reduction potential than zinc or iron. Thus, in hydro-metallurgy iron and zinc can be used to displace copper from its solution.

Fe(s) + Cu2+(aq) ⇒ Fe2+ (aq) + Cu(s)

However, in order to displace zinc a metal more reactive than it is required e.g. K, Ca , etc. The problem arising now is that all these metals react with water to liberate hydrogen gas. Thus, they cannot be used for the extraction of zinc using hydro-metallurgy.