Question

Nickel is purified by thermal decomposition of its ________________.

Answer 1

Hint: Nickel has the chemical symbol Ni and 28 is its atomic value. Thermolysis, or thermal decomposition, is a process where the breakdown of chemical structures takes place by the application of heat. When a substance is thermally decomposed, the temperature at which the breakdown takes place is called the element's decomposition temperature.

Complete answer:
Nickel is a silvery-white metal that is rigid but is easily bendable, and stretchable. It is a strong heat and electricity conductor.
Ludwig Mond developed the Mond's procedure, also known as the carbonyl process that uses thermal decomposition method, to purify nickel by isolation.
The Mond's process for nickel extraction and refining is premised on the idea that when impure nickel along with carbon monoxide is heated at high temperatures to produce a compound that is nickel tetracarbonyl, a volatile compound.
$Ni\;(impure) + 4CO\xrightarrow{{56 - {{76}^ \circ }C}}Ni{(CO)_4}$
(In the above equation: $Ni$ is Nickel metal, $CO$ is carbon monoxide, and $Ni{(CO)_4}$ is Nickel tetracarbonyl)
The produced nickel tetracarbonyl can then be broken down at a higher temperature to yield a pure metal form of nickel.
$Ni{(CO)_4}\xrightarrow{{{{200}^ \circ }C}}Ni\;(pure) + 4CO$​
Here decomposition happens, since a single reactant ‘nickel tetracarbonyl’ is broken down to get pure nickel metal, so we decomposed a carbonyl of nickel to purify the metal nickel.
The combined reactions can be illustrated as follows:
$Ni\;(impure) + 4CO\xrightarrow{{56 - {{76}^ \circ }C}}Ni{(CO)_4}\xrightarrow{{{{200}^ \circ }C}}Ni\;(pure) + 4CO$
Therefore the thermal decomposition of ‘Nickel tetracarbonyl’ produces a purified form of nickel.

Note:
The most important use of the chemical substance 'nickel' is in coin production. This element is also used for the production of wires. Because of its ability to withstand corrosion especially at higher temperatures, it can be utilized in making equipment like engines of rockets and gas turbines. It is also used widely to create a number of alloys, to produce nails, pipes and also for armour plating.