Write names of three methods used for refining of metals.

The method to obtain about 100% pure metal by removing impurities in very small amounts in metal is called refining.

The three methods used for refining of metals are:

i) Electrolysis: In this method the rod of impure metal is taken as anode and rod of pure metal as cathode. The aqueous solution of salt of metal acts as electrolyte, when current is passed anode dissolves in electrolyte and the same amount of metal is deposited on cathode.

ii) Liquefaction: In this method furnace having a slope is used and the temperature of the furnace is kept higher than the melting point of metal.

When the impure metal is passed on the slope, the metal in it get melted and collected in the vessel but the melting point of impurities is high so they remain on the slope in solid form.

iii) Zone refining: In this method we remove trace impurities which are generally more soluble in molten metal, their solubility decreases as the metal cools and impurities are separated in the form of crystals.