Physical Properties, purification and Alloys of Copper for std 11 & 12

Copper Metal

COPPER
Copper is one of the metals known for a long time. Extraction of copper from its ores was known even in 5000 B.C.. It is a transition element with atomic number 29 and mass number 64. its symbol is Cu. Its electronic configuration is 

Copper electronic configuration

In our country copper ores occur in Karnataka, Garval region of Himalayas, Rajsthan, Sikkim amd also in Bihar. These oress also occur in Southern Africa, United States of America, Russia, China, Mexico ad Chilli. 

Extraction from copper pyrites : 

the finely powdered ore is mixed with pine oil and water in a large tank. The sulphide ore mixes with oil and forms a thin film. Oil does not have affinity for earthly materials. The materials other than the ore particles are wetted by water. When air is bubbled through the mixture, forth containing the particles of copper ore floats on top of water and can be skimmed off easily. This method, used to concentrate copper ore, is called frothflotation.

The ore is separated and roasted in a current of air. Copper sulphide and ferrous oxide are formed.

The product is mixed with sand and is heated in a furnace. Ferrous oxide forms ferrous silicate; this is removed as liquid slag. The remaining copper sulphide when roasted in air, forms cuprous oxide (Cu2O).

At this stage, supply of air is stopped. Cuprous oxide reacts with cuprous sulphide to form molten copper.

Copper in the liquid state is allowed to cool. As it solidities dissolved sulphur dioxide comes out and blisters are formed on the surface of copper. Hence copper so obtained is called blister copper which is impure. It is subjected to purification.

Purification of copper :
Purification of copper is done by electrolytic refining. A set of thick impure copper plates are connected together and dipped in copper sulphate solution taken in a tank. Copper sulphate is the electrolyte. A set of thin pure copper plates are connected together and dipped into the same solution such that the impure copper plates are interposed between the pure copperplates (Fig). 

Purification of Copper

The set of pure copper plates is made cathode and the set of impure copper plates is made anode. This is done by connecting the sets to appropriate terminals of a battery. On passing direct current copper at the anode dissolves and get deposited on the cathode. The mass of cathode plates increases and that of anode plates decreases. Copper so obtained is 100 % pure.

Physical properties of copper :
Copper is a rose red heavy metal. It is malleable and ductile. It is a very good conductor of electricity and heat. Thermal conductivity of copper is next only to the thermal conductivity of silver. It has high melting point and high boiling point.

Alloys : 

Alloy is a homogeneous mixture of (a) two or more metals, or (b) metals and non-metals. The properties of alloys are different from the parent elements. An alloy is called a solid solution. The homogeneous mixture is produced in molten state and then solidified. Alloys are widely useful because of their special properties.

Alloys of copper : 

Some important alloys of copper with their components and uses are listed below.

Alloys of Copper.