Question

Blister copper is:
A.Electrolytically refined copper
B.A mixture of impure copper and silver
C.Copper containing 2% impurity
D.Present in the anode mud in an electrolytic process

Answer 1

Hint: To answer this question, you must recall the various forms of copper produced during its extraction from its ores. Commonly, the process of smelting is used for the extraction of copper from its sulphide ores. Blister copper is the second most pure form of copper next to the electrically refined which is 100% pure.

Complete step by step answer:
In the process of extraction of copper, blister copper is obtained by the reduction of copper matte. Copper matte is a combination of iron sulphide and copper sulphide which is extracted and formed prior to the final step. It generally contains around 30-70% copper in the form of copper sulphide and the remaining part is iron sulphide. The copper matte is taken in the molten state and air is blown through it at a very high temperature. The Sulphur present in the copper sulphide is removed as Sulphur dioxide.
$2C{u_2}S + 3{O_2} \to 2C{u_2}O + 2S{O_2}$
$2C{u_2}O + C{u_2}S \to 6Cu + S{O_2}$
The copper obtained in this reaction is known as blister copper.
Blister copper is known so because of its broken surface which is formed when the Sulphur dioxide escapes the metal as it solidifies. It is around 98% pure and contains impurities of iron mainly and in small amounts, those of Arsenic, Zinc, Lead, gold and silver. Thus, it is copper containing 2% impurity.

Thus, the correct answer is C.

Note:
The above process of formation of blister copper is known as Bessemerization process. The blister copper obtained is purified further by electrolysis. The anode is made up of blister copper and the cathode is made up of pure sheets of copper coated with graphite. On electrolysis, the impurities fall to the bottom and pure copper deposits on the cathode.