Question

Which method is used to refine impure metals?

Answer 1

Metal can be made pure via a variety of techniques:

Distillation:

• Metals with an extremely low boiling point include mercury and zinc.
• As a result, when heated, zinc and mercury easily vaporize, leaving their impurities behind.
• In a furnace, the remaining impure metal is heated over its melting point.
• Once the impurities are removed, the vapors are transformed back into metals.

Liquidation:

• Tin and other metals with low melting points are good candidates for liquidation.
• The impure metal is heated during the liquidation process, after which it flows over a sloping surface.
• The pure metal will accumulate at the bottom of the slope while the impurities are left behind to flow.

Poling:

• Poling is a technique used to clean up metals with oxidized impurities.
• Poling is mostly used to clean up metals like copper or tin that are in their impure forms like copper oxide or tin oxide.
• The still-green log of wood used in the poling procedure is used to agitate the liquid metal.
• The green wood's hydrocarbons corrode the metal, and oxygen escapes as ${\mathrm{CO}}_2$ gas.

Electrolytic Refining:

• Because it works with the majority of metals, electrolytic refining is the most typical and often used process.
• Different electrochemical characteristics of the metals and contaminants are exploited in electrolytic refining.
• The impure metal serves as the anode and the pure metal as the cathode in electrolytic refining.
• The salt solution of the same metal that conducts electricity is known as an electrolyte.
• The electrolyte solution will dissolve the pure metal that is removed from the anode, which will then gather at the anode.
• The discovered impurities will either dissolve or be discovered in a pile near the anode's base.

Vapour-Phase Refining:

• In vapour-phase refining, metal is heated to create a suitable volatile compound before being released from impurities.
• When combined with the appropriate reagent, the metal utilised in this method should generate a volatile chemical.
• The volatile substance that will be employed should be simple to break down so that recovery is simple.

Zone Refining:

• It is a unique technique used to clean up metals.
• Metals are extremely thoroughly refined with this technique.
• A container containing inert gas is filled with a rod of impure metal.
• The impure metal is then heated by a circular heater that is positioned around the top rod.
• The pure metal cools and crystallizes as the heater switches to the subsequent zone.
• The melted impurities will migrate to the following zone when the heater moves to the next zone.
• After being gathered in the final zone, all of these contaminants may then be separated.