Question

Polling process is employed for the removal of:
A) From Cu
B) From Al
C) From Fe
D) None of the above

Answer 1

Hint: In metallurgy, refining consists of purifying an impure metal. It is to be distinguished from other processes such as smelting and calcining in that those two involve a chemical change to the raw material, whereas in refining, the final material is usually identical chemically to the original one, only it is purer. The processes used are of many types, including pyrometallurgical and hydrometallurgical techniques.

Complete step-by-step answer:
Polling is a metallurgical method employed in the purification of copper which contains cuprous oxide as an impurity. In the past, freshly cut trees were used as wooden poles. The sap in these poles acted as the reducing agent. The heat of the copper makes the pole emit a gas that reduces the cuprous oxide to copper.

Poling is a method used to purify metals that have oxidized impurities. It is typically used to purify metals like copper or tin that are in the impure form of copper oxide or tin oxide. A log of wood that is still green is used to stir the liquid metal. The hydrocarbons in the greenwood can reduce the metal & the oxygen leaves as carbon-dioxide gas.

Hence the correct answer is option ‘A’.

Note: Types of Purification:
A large number of methods are available for the purification of substances. The choice of method, however, depends upon the nature of the substance (whether solid or liquid). It also depends on the type of impurities present in it. We commonly use these methods for purification of substances:
-Simple crystallization
-Fractional crystallization
-Sublimation
-Simple distillation
-Fractional distillation
-Distillation under reduced pressure
-Steam distillation