Question

The reaction representing the Mond process for metal refining is _________.

• A. \(2\text{K[Au(CN)}_2] + \text{Zn} \xrightarrow{\Delta} \text{K}_2[\text{Zn(CN)}_4] + 2\text{Au}\)
• B. \(\text{Ni} + 4\text{CO} \xrightarrow{\Delta} \text{Ni(CO)}_4\)
• C. \(\text{Zr} + 2\text{I}_2 \xrightarrow{\Delta} \text{ZrI}_4\)
• D. \(\text{ZnO} + \text{C} \xrightarrow{\Delta} \text{Zn} + \text{CO}\)

Hint:

For refining processes:
• Mond process is specific to nickel and involves the formation of a volatile carbonyl compound.
• Identify the reactions forming volatile compounds for easy separation and purification.

Answer 1

The Correct Option is B

The question asks for the reaction that represents the Mond process for metal refining. The Mond process is a technique created by Ludwig Mond to extract and purify nickel. This process involves the following steps:

1. Nickel is first reacted with carbon monoxide at a temperature of approximately 50-60°C to form nickel tetracarbonyl, \text{Ni(CO)}_4:
   \text{Ni} + 4\text{CO} \xrightarrow{\Delta} \text{Ni(CO)}_4
2. This reaction is reversible and occurs at low temperature, forming a volatile compound \text{Ni(CO)}_4.
3. The nickel tetracarbonyl is then decomposed at higher temperatures (around 200°C) to regenerate nickel and carbon monoxide:
   \text{Ni(CO)}_4 \xrightarrow{\Delta} \text{Ni} + 4\text{CO}

Based on the provided options, the reaction that matches the first step of the Mond process is:

\text{Ni} + 4\text{CO} \xrightarrow{\Delta} \text{Ni(CO)}_4

This reaction represents the formation of nickel tetracarbonyl from nickel and carbon monoxide and is the cornerstone of the Mond process.

Conclusion: The correct answer is the second option: \text{Ni} + 4\text{CO} \xrightarrow{\Delta} \text{Ni(CO)}_4. This represents the Mond process used for refining nickel by converting it into its volatile carbonyl form and then decomposing it to obtain pure nickel.