Question

When the more electropositive metal displaces less electropositive metal from its salt solution, this process is called:

• A. auto reduction
• B. electro reduction
• C. hydrometallurgy
• D. none of these

Hint:

Cementation (metal displacement) is a part of hydrometallurgy.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Hydrometallurgy is a technique used in metallurgy to obtain metals from their ores by treating them with aqueous solutions. A key step in this process is the displacement of a metal from its salt solution by a more reactive (more electropositive) metal.
Step 2: Detailed Explanation:
In hydrometallurgy, the metal is first brought into an aqueous solution as a soluble salt.
Then, a more electropositive metal is added to the solution.
According to the electrochemical series, the more electropositive metal will reduce the metal ions of the less electropositive metal.
Example: Extraction of Silver using Zinc.
\[ 2[\text{Ag(CN)}_{2}]^{-}(\text{aq}) + \text{Zn}(\text{s}) \longrightarrow [\text{Zn(CN)}_{4}]^{2-}(\text{aq}) + 2\text{Ag}(\text{s}) \]
Zinc (more electropositive) displaces Silver (less electropositive) from its cyanide complex.
Step 3: Final Answer:
The process is known as hydrometallurgy.