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

Answer: (B)

nickel reacts with carbon monoxide to form nickel carbonyl which decomposes at high temperature to form nickel

Nickel metal is purified by the vapour phase refining process. This process is based on the fact that nickel reacts with carbon monoxide to form highly volatile nickel tetracarbonyl which decomposes at high temperature to form pure nickel metal.
$Ni+4CO\stackrel{\text{330-350 K}}{\to }Ni(CO{)}_4$
$Ni(CO{)}_4\stackrel{\text{450-470 K}}{\to }\underset{\text{Pure metal}}{Ni}+4CO$