Question

ASSERTION: Chalcolite is roasted and not calcined during the recovery of copper.
REASON: Chalcolite is a sulphide ore of copper; therefore, it must be roasted in the presence of air to get oxide.
Read the above assertion and reason and choose the correct option regarding it.
A) Both assertion and reason are correct and reason is the correct explanation for assertion.
B) Both assertion and reason are correct but reason is not the correct explanation for assertion.
C) Assertion is correct but reason is incorrect.
D) Both assertion and reason are incorrect.

Answer 1

Hint: The answer to this question includes the fact that roasting involves removal of impurities in the presence of excess of air and converts into oxides as well and calcination does not convert obtained material into oxides.

Complete step by step solution:
We have learnt in our chemistry classes about the concepts which deal with the extraction and purification of metal from its metal ores.
- There are many methods used for the purification based on the properties of the metal ores and among them roasting and calcination are used.
- Roasting method involves heating of an ore to a high temperature in the presence of air.
- On the other hand, calcination is the one which involves heating of metal ores to a high temperature for the purpose of removing volatile substances in the absence of air or may also be in the limited supply of air.
-In this question, the chalcolite is the sulphide ore mineral of copper and since it contains sulphur as impurity, it can be removed by roasting as roasting process also convert copper sulphide to copper oxide in the presence of air which is a reduction process.
This is as shown below,
$2C{{u}_{2}}S+3{{O}_{2}}\to 2C{{u}_{2}}O+S{{O}_{2}}$
This copper oxide obtained reacts further with sulphide ore to give the copper metal. The reaction is as follows,
$C{{u}_{2}}S+2C{{u}_{2}}O\to 6Cu+S{{O}_{2}}$
Therefore, By the roasting method we get oxide and this can be converted to the desired metal. On the other hand calcination makes use of limited supply of air and thus it cannot efficiently convert copper sulphide to copper oxide.

Thus, the correct answer to this question is option A)

Note: You must be thorough with the fact that calcination is mostly used for the oxidation of carbonates while roasting is the method which is used for converting sulphide ores to oxides which involves the requirement of air supply.