Question

Name the method used for refining of nickel metal?

Answer 1

Refining is a process which is used to purify a substance from its impure form, the refining is usually done for a substance that is almost in a usable form, but which is more useful in its pure form and nickel is one of the element which is purified industrially, Nickel is a chemical element with the symbol Ni and atomic number 28. It is a silver-white metal with a light gold colour as well. Nickel is a hard metal and also exhibits ductility (a property of a metal to be drawn into a wire).

Complete step by step answer:
The process for purification or refining of pure Nickel is called as Mond’s process, it is based on the principle that nickel is heated in the presence of carbon monoxide to form nickel tetracarbonyl or $NiC{O_4}$, which is a volatile compound, where nickel is heated at a temperature of approximately $330 - 350K$ to produce nickel tetracarbonyl, and the formed compound is further heated at a temperature of approximately $450 - 470K$ and is decomposed and leads to a formation of pure nickel metal.

The step by step reactions involved in the process are as follows:
$Ni + 4CO\xrightarrow{{330 - 350K}}Ni{\left( {CO} \right)_4}$
$\;Ni{\left( {CO} \right)_4}\xrightarrow{{450 - 470K}}Ni + 4CO$

Note:
The impure nickel metal which is in solid state usually is a product obtained from nickel oxide and some impurities are present within the product. The $NiO$ is reacted with a mixture of hydrogen gas and carbon monoxide gas called as syngas, and the impure nickel metal is formed. The reaction for the formation of the impure solid nickel with some impurities as well is shown as follows:
$NiO(s) + {H_2}(g) \to Ni(s) + {H_2}O(g)$.