Question

From which of the following reaction blister copper is obtained?
(A.) $Cu_{ 2 }S+FeO\rightarrow 2Cu+FeO$
(B.) $Cu_{ 2 }S+FeS\rightarrow 2Cu+FeS_{ 2 }$
(C.) $Cu_{ 2 }S+2Cu_{ 2 }O\rightarrow 6Cu+SO_{ 2 }$
(D.) $Cu^{ 2+ }+Fe\rightarrow Fe^{ 2+ }+Cu$

Answer 1

Hint: We should know that an impure form of copper has a blister-like surface due to the release of gas during cooling. Now try to find the answer accordingly.

Complete step by step answer:

We should know that the commonest ore used in the extraction of copper is Chalcopyrite ($CuFeS_{ 2 }$) also known as Copper Pyrites.
The concentration of ore is required and it is done by the Froth Flotation Method.Initially, the ore is crushed into a fine powder and a suspension is created in the water.
Collectors (pine oils, fatty acids, etc) are added to increase the non-wettability of the metal part of the ore and allow it to form froth and Froth Stabilizers (cresols, aniline, etc) are added to sustain the froth. The oil wets the metal and the water wets the gangue.
Copper Smelting means that the concentrated ore is heated strongly with silicon dioxide (silica), calcium carbonate ($CaCO_{ 3 }$), and air in a furnace.
Copper in Chalcopyrite is reduced to copper sulfide.
$2CuFeS_{ 2 }+2SiO_{ 2 }+4O_{ 2 }\rightarrow Cu_{ 2 }S+2FeSiO_{ 3 }+3SO_{ 2 }$
Impurities like FeS are preferentially oxidized prior to $Cu_{ 2 }S$.
$2FeS+3O_{ 2 }\rightarrow 2FeO+2SO_{ 2 }$
The FeO forms a slag (FeO.$SiO_{ 2 }$) with silica. The molten mass separates as the top layer of slag ($FeSiO_{ 3 }$) and the lower layer is of copper matte mainly composed of $Cu_{ 2 }S$ and FeS.
The molten matte is further oxidized in the air when the remaining FeS is mainly oxidized. After removing the slag, the copper sulfide is partly oxidized by air to $Cu_{ 2 }O$, and this $Cu_{ 2 }O$ then combines with the remaining $Cu_{ 2 }S$, producing copper.
$2Cu_{ 2 }S + 3O_{ 2 }\rightarrow 2Cu_{ 2 }O + 2SO_{ 2 }$
$2Cu_{ 2 }O+Cu_{ 2 }S\rightarrow 6Cu+SO_{ 2 }$
The sulfur dioxide escapes the copper and this causes bubbles to appear and burst as SO2 leaves. This causes the final product to have a very blistery appearance and hence it is called Blister Copper; 98 – 99.5 % pure.

Therefore, we can conclude that the correct answer to this question is option C.

Note: We should know that Smelting is a metallurgy technique to extract base metals from their ores with the help of heat and a chemical reducing agent.