Question

Which of the following is an application of coordination compounds?

• A. Manufacture of soap only
• B. Extraction of metals
• C. Production of plastics only
• D. Preparation of fertilizers only

Hint:

Metallurgical processes like the extraction of gold/silver and the Mond process for purifying nickel are classic textbook applications of coordination chemistry.
Keep these key processes in mind as they are frequently tested in board and competitive examinations.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
This question asks us to identify a correct, real-world application of coordination compounds from the provided industrial processes.

Step 2: Key Formula or Approach:
Coordination complexes are widely used in metallurgy because of their ability to form stable, soluble complexes with precious metals.

Step 3: Detailed Explanation:

• Role in Metallurgy: Coordination compounds play a critical role in the extraction of metals like gold and silver from their ores.
  
• Gold Extraction Process: In the cyanide process, crushed gold ore is treated with an aqueous solution of sodium cyanide in the presence of air to form a soluble cyano-complex:
  \[ 4\text{Au} + 8\text{CN}^- + 2\text{H}_2\text{O} + \text{O}_2 \rightarrow 4[\text{Au}(\text{CN})_2]^- + 4\text{OH}^- \]
  
• Metal Recovery: The gold metal is subsequently recovered from this stable coordination complex by displacement with zinc:
  \[ 2[\text{Au}(\text{CN})_2]^- + \text{Zn} \rightarrow [\text{Zn}(\text{CN})_4]^{2-} + 2\text{Au} \]
  
• Purification of Nickel: Nickel is purified via the Mond process by forming a volatile coordination complex, nickel tetracarbonyl (\([\text{Ni}(\text{CO})_4]\)).
  
• Evaluating Other Options: Soaps, plastics, and typical chemical fertilizers are not manufactured through coordination complex pathways, making options A, C, and D incorrect.
  

Step 4: Final Answer:
The extraction of metals is a primary application of coordination compounds, which is option (B).