Question

Liquidation method is used to refine which of the following crude metal?
A) Silver
B) Lead
C) Mercury
D) Copper

Answer 1

Hint: The liquation method is used to refine the metal when impurity has a higher melting point than the metal. Using standard melting points of given metals determine which metal has a lower melting point.

Complete answer:
Liquation is one of the purification methods of metal from its ore. The liquation method is used when the impurity is less fusible than the metal itself. The impure metal is heated on the sloping hearth of a furnace. The metal melts and flows down leaving behind the infusible material on the hearth. Metals like \[{\text{Hg, Sn, Pb, Bi, Zn }}\]etc are purified by liquation.
- The melting point of Silver is \[{\text{961}}{\text{.8 }}^\circ {\text{C}}\].
- The melting point of lead is \[{\text{327}}{\text{.5 }}^\circ {\text{C}}\].
- The melting point of mercury is \[{\text{ - 38}}{\text{.83 }}^\circ {\text{C}}\].
- The melting point of copper is \[{\text{1085 }}^\circ {\text{C}}\].
As the melting point of silver and copper is high cannot be extracted using the liquation process. As the melting point of both lead and mercury is low these metals can be refined using the liquation method.

Thus, correct options are options (B) and (C).

Note:
There are various refining methods used for purification metal. The choice of refining method depends on the metal, impurities present in ore and their melting points. Students must know the physical properties of metals to determine the refining method. The liquation method is used to extract the metals having a lower melting point than the impurities. The other criteria are impurity should not be miscible with the metals. In this method after heating impurity remains in a solid-state while metals melt in a liquid state.