Question

Heating the mixture of $ {\text{C}}{{\text{u}}_{\text{2}}}{\text{O}} $ and $ {\text{C}}{{\text{u}}_{\text{2}}}{\text{S}} $ will give:
(A) $ {\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{3}}} $
(B) $ {\text{CuO}} + {\text{CuS}} $
(C) $ {\text{Cu}} + {\text{S}}{{\text{O}}_3} $
(D) $ {\text{Cu}} + {\text{S}}{{\text{O}}_2} $

Answer 1

Hint: A chemical reaction involves the reaction of the reactants with each other under suitable conditions to yield products. Some reactions may be slow while some may be fast. To answer this question, you must recall the reaction between Copper Oxide ( $ {\text{C}}{{\text{u}}_{\text{2}}}{\text{O}} $ ) and copper sulphide ( $ {\text{C}}{{\text{u}}_{\text{2}}}{\text{S}} $ ). Heating the given mixture involves a self- reduction reaction along with formation of an oxide.

Complete step by step solution:
In a self- reduction reaction, less electropositive metals are heated in presence of oxygen in order to convert their ores into their oxides and sulphates. These oxides of sulphates so formed, react with the remaining metal sulphide in the ore to yield pure metal. It is a very important reaction for the extraction of various metals including copper.
When copper oxide is heated with copper sulphide, a similar reaction takes place which gives copper metal and sulphur dioxide gas as the products. The reaction can be written as:
 $ {\text{2C}}{{\text{u}}_{\text{2}}}{\text{O}} + {\text{C}}{{\text{u}}_{\text{2}}}{\text{S}} \to 6{\text{Cu}} + {\text{S}}{{\text{O}}_2} $
Copper oxide is cuprous oxide and the oxidation state of copper in the compound is +1, which after reaction gives copper in the elemental state, i.e. it has zero oxidation state. Copper is reduced and thus the reaction is known as self- reduction.
So we can conclude by saying that the heating of a mixture of $ {\text{C}}{{\text{u}}_{\text{2}}}{\text{O}} $ and $ {\text{C}}{{\text{u}}_{\text{2}}}{\text{S}} $ will give $ {\text{Cu}} + {\text{S}}{{\text{O}}_2} $ as products.
The correct option is D.

Note:
This reaction is used commonly in the Bessemerisation process for the extraction of metals. The ores of less electropositive metals namely the sulphide ores are heated in air which give pure metal. Copper sulphide is commonly known as copper glance while copper oxide is known as cuprite.