3.4.6 Refining of Metals

. . Refining of Metals The metals produced by various reduction processes described above are not very pure. They contain impurities, which must be removed to obtain pure metals.

The most widely used method for refining impure metals is electrolytic refining. Electrolytic Refining: Electrolytic Refining: Electrolytic Refining: Electrolytic Refining: Electrolytic Refining: Many metals, such as copper, zinc, tin, nickel, silver, gold, etc., are refined electrolytically. In this process, the impure metal is made the anode and a thin strip of pure metal is made the cathode. A solution of the metal salt is used as an electrolyte.

The apparatus is set up as shown in Fig. . . On passing the current through the electrolyte, the pure metal from the anode dissolves into the electrolyte.

An equivalent amount of pure Figure . Figure . Figure . Figure .

Figure . Thermit process for joining railway tracks Figure . Figure . Figure .

Figure . Figure . Electrolytic refining of copper. The electrolyte is a solution of acidified copper sulphate.

The anode is impure copper, whereas, the cathode is a strip of pure copper. On passing electric current, pure copper is deposited on the cathode. metal from the electrolyte is deposited on the cathode. The soluble impurities go into the solution, whereas, the insoluble impurities settle down at the bottom of the anode and are known as anode mud.

. Define the following terms. (i) Mineral (ii) Ore (iii) Gangue . Name two metals which are found in nature in the free state.

. What chemical process is used for obtaining a metal from its oxide?