Metallurgy — Chemistry STD 12 — Question

The impure nickel is heated in a stream of carbon monoxide at around 350 K. The nickel reacts with the CO to form a highly volatile nickel tetracarbonyl. The solid impurities are left behind.

$Ni _{( s )}+4 CO _{( g )} \longrightarrow Ni ( CO )_{4( g )}$

On heating the nickel tetracarbonyl around 460 K, the complex decomposes to give pure metal.

$Ni ( CO )_{4( g )} \longrightarrow Ni _{( s )}+4 CO _{( g )}$