Question

You are given the description of a process called “Vapour phase refining” Vapour Phase Refining: This involves converting the crude metal into a volatile intermediate. This intermediate should also decompose on heating at a reasonable temperature. Which of the following could be categorized under ‘Vapour phase refining’?

• A. Baeyer’s process
• B. Mond’s Process
• C. Mac-Arthur Forrest (Cyanide) process
• D. Van Arkel de-Boer process

Answer 1

Answer: (B), (D)

Van Arkel de-Boer process

Refer to the video on vapour phase refining.

Mond’s process:

$Ni\left(s\right)$ $+4CO\left(g\right)$ $\to$ $Ni(CO{)}_4$ (g) happens at $50-{60}^{\circ }C$

$Ni\left(CO{)}_4\right(g)$ $\to$ $Ni\left(s\right)$ $+4CO\left(g\right)$ at $150-{180}^{\circ }C$

As you can see, Mond’s process is a good example of vapour phase refining.

Van Arkel Method: The impure metal is converted to volatile compound, impurities being unaffected. Thus formed pure volatile compound is decomposed electrically to get the pure metal. Hence this is a method to obtain ultra pure metal.

For example:

$Zr\left(Impure\right)$ $+2I_2$ $\to$ $Zr{I}_4$ $\left(Gas\right)$

$Zr{I}_4$ $\left(Gas\right)$ $\to$ $Zr\left(Pure\right)$ $+2I_2$