Question

Vapour phase refining of nickel is carried out using:
(A)- ${{I}_{2}}$
(B)- $C{{l}_{2}}$
(C)- HCl
(D)- CO

Answer 1

Hint: The process of obtaining the pure metal from an impure method or the mixture is known as refining. In refining, the final product obtained is usually chemically identical to the original one.

Complete step by step answer:
-Refining of nickel method is done by vapor phase refining method-
Vapor phase refining- For this type of refining process, the metal should form a volatile compound in the presence of a reagent and it should be easily decomposed to recover the metal. Metals like nickel, zirconium, and titanium are refined using this method.
-To make the volatile complex of nickel, it is heated in a stream of carbon monoxide. The volatile state of
nickel metal is nickel tetracarbonyl, which is further decomposed to obtain pure nickel metal.

$\begin{align}
 & Ni+4CO\xrightarrow{330-350K}Ni{{(CO)}_{4}} \\
 & Ni{{(CO)}_{4}}\xrightarrow{450-470K}Ni+4CO \\
\end{align}$

So, the correct answer is “Option D”.

Note: Following are the other two methods other than the vapor phase refining method for the purification of metals –
(i) Zone refining- The idea that the impurities are more soluble in the molten state of metal than the metal in the solid-state forms the principle of the Zone refining process. In the zone refining process, the rod of impure metal is fixed in a circular mobile heater. As the mobile heater moves, the molten zone of the rod also moves and starts melting. The impurities are passed to the adjacent molten zone. The impurities are segregated at one end of the rod and the process is repeated till all the impurities are separated. Metals such as germanium, silicon, gallium, indium, and boron are refined with this method.

(ii) Electrolytic refining- When the refining of metals involves the use of electricity, it is known as the electrolytic refining process. In this process, the impure metal acts as an anode, and the pure metal act as a cathode. A solution of a soluble salt of the same metal is prepared and taken as an electrolyte. When the electricity is passed through the electrolytic cell, the metal ions from the electrolyte are deposited at the cathode as the pure metal from the anode dissolves in the electrolyte in the form of ions. The impurities present in the impure metal now get collected below the anode and this anode is now known as anode mud, and thus the pure metal is separated from its impurities.