Question

Mond's process is used for refining ___. Whereas van Arkel method is used for refining ___.

• A. lead, zirconium
• B. zirconium, nickel
• C. nickel, lead
• D. nickel, titanium

Hint:

Mond $\longrightarrow$ Ni (carbonyl), Van Arkel $\longrightarrow$ Ti/Zr (iodide purification).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Refining of metals involves vapor phase methods where the metal is converted into a volatile compound and then decomposed to give pure metal. Mond's process and van Arkel method are the two primary techniques in this category.
Step 2: Detailed Explanation:
1. Mond's Process: This is used specifically for refining Nickel (Ni). Nickel is heated in a stream of carbon monoxide to form a volatile complex, nickel tetracarbonyl, which is then decomposed at higher temperatures to yield pure nickel.
\[ Ni + 4CO \xrightarrow{330-350 K} Ni(CO)_4 \xrightarrow{450-470 K} Ni + 4CO \]
2. van Arkel Method: This method is used for refining Zirconium (Zr) and Titanium (Ti). The crude metal is heated in an evacuated vessel with iodine to form a volatile metal iodide, which is then decomposed on a tungsten filament at very high temperatures.
\[ Ti + 2I_2 \xrightarrow{523 K} TiI_4 \xrightarrow{1700 K} Ti + 2I_2 \]
Step 3: Final Answer:
Mond's process is used for Nickel and van Arkel for Titanium (or Zirconium). Option D is correct.