Question

Nickel metal is purified by the vapour phase refining process. This process is based on the fact that
A.Nickel metal sublimes at high temperature
B.Nickel reacts with carbon monoxide to form nickel carbonyl which decomposes at high temperature to form nickel.
C.Nickel reacts with chlorine to form nickel chloride which is volatile and decomposes easily to nickel.
D.Nickel can be vapourized under vacuum leaving behind impurities.

Answer 1

Hint: We can refine a metal using the process of vapour phase. In this method, we have to convert impure metal to its volatile compound by heating it with reagent. We have to decompose the volatile compound by heating to obtain the pure metal.

Complete step by step answer:
We have to know in metallurgy, the process of refining plays an important role. Any metal extracted from its ore is impure and the impure metal that is extracted is known as crude metal.
When we purify a metal in vapour phase refining, the metal has to form a volatile compound in reagent’s presence and it must decompose to recover the metal. We can convert the impure metal to volatile compound and the volatile compound is decomposed to yield pure metal.
We can purify metals such as nickel, zirconium and titanium by vapour refining process.
In the vapour phase refining of nickel, we react nickel with carbon monoxide to form nickel tetracarbonyl. Nickel tetracarbonyl is a volatile compound and it undergoes decomposition at high temperatures to yield nickel.
We can write the chemical equation as,
$
  Ni + 4CO\xrightarrow{{330 - 350\,K}}Ni{\left( {CO} \right)_4} \\
  Ni{\left( {CO} \right)_4}\xrightarrow{{450 - 470\,K}}Ni + 4CO \\
 $

$\therefore $ Option (B) is correct.

Note:
We must know that the Mond’s process is the other name for refining nickel by vapour phase refining. The refining of zirconium is done by the Van Arkel method. We can obtain highly purified metals in the process of refining as it removes impurities. There are several methods to refine a metal based on properties of impurities and on the properties of metals. Some of the methods involved are,

1.Distillation
2.Liquidation
3.Zone refining
4.Electrolysis
5.Chromatography