CBSE Class 12-science Answered

refer to Ellingham diagram:

In the graph of delta G⁰ vs T for formation of oxides, the Cu₂O line is almost at the top. So it is quite easy to reduce oxide ores of copper directly to the metal by heating with coke (both the lines of C, CO and C, CO₂ are at much lower positions in the graph particularly after 500 – 600K.

However, since most of the ores of copper are sulphide ores, these are first converted to oxides. The oxide is then easily reduced to metallic copper with coke.