Question

What happens when
(a) $ZnC{O_3}$ ​ is heated in the absence of oxygen?
(b) a mixture of $C{u_2}O$ and $C{u_2}S$ is heated?

Answer 1

An ore is a mineral containing sufficient metal to make the metal worth extracting. To remove metals from certain metal oxides, carbon may be used. In a reaction, a metal may either be reduced or oxidised. If a metal lacks oxygen in a compound, reduction occurs to form the elemental metal.

Complete step by step answer
Zinc oxide and carbon dioxide are formed when zinc carbonate is heated in the absence of oxygen. In the absence of oxygen, the reduction process of carbonate ores to form oxides is called calcination. In its ore-zinc carbonate, zinc is found. Zinc oxide is formed along with carbon dioxide when this ore is heated. The following reaction takes place:
$ZnC{O_3} \to ZnO{\text{ }} + {\text{ }}C{O_2}$
Zinc zinc oxide carbon dioxide
carbonate
(calamine)
Pure copper is obtained when a mixture of copper oxide and copper sulphide is heated. It goes into auto reduction. A part of this ore is converted into oxide when the sulphide ore of copper is heated, which then reacts to the remaining sulphide ore to provide pure copper and sulphur dioxide.
$2C{u_2}O{\text{ }} + {\text{ }}C{u_2}S \to 6Cu{\text{ }} + {\text{ }}S$ .

Note
The copper (I) sulfide formation mechanism has been investigated in the segregation process. Synthetic model mixtures of quartz sand, copper (II) oxide and an admixture of sulfate elements of the I-st or II-nd group were subjected to segregation tests. X-ray structural analysis and microscopic observations have established the products of segregation. Copper (I) sulfide has been found to be formed only in the presence of group II sulfates which, in the segregation process, undergo a reduction to the appropriate sulfides and decompose with the evolution of hydrogen sulfide upon contact with gaseous hydrogen chloride. Hydrogen sulfide thus formed subsequently reacts with copper metal and/or $C{u_3}C{l_3}$ , giving rise to copper (I) sulfide.