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JEE Advance - Chemistry (2010 - Paper 1 Offline - No. 24)

Copper is the most noble of the first row transition metals and occurs in small deposits in several countries. Ores of copper inculcated chalcanthite (CuSO$$_4$$ . 5H$$_2$$O), atacamite (Cu$$_2$$Cl(OH)$$_3$$), cuprite (Cu$$_2$$O), copper glance (Cu$$_2$$S) and malacite (Cu$$_2$$(OH)$$_2$$CO$$_3$$). However, 80% of the world copper production comes from the ore of chalcopyrite (CuFeS$$_2$$). The extraction of copper from chalcopynite involves partial roasting, removal of iron and self-reduction.
Copper is the most noble of the first row transition metals and occurs in small deposits in several countries. Ores of copper inculcated chalcanthite (CuSO$$_4$$ . 5H$$_2$$O), atacamite (Cu$$_2$$Cl(OH)$$_3$$), cuprite (Cu$$_2$$O), copper glance (Cu$$_2$$S) and malacite (Cu$$_2$$(OH)$$_2$$CO$$_3$$). However, 80% of the world copper production comes from the ore of chalcopyrite (CuFeS$$_2$$). The extraction of copper from chalcopynite involves partial roasting, removal of iron and self-reduction.
Copper is the most noble of the first row transition metals and occurs in small deposits in several countries. Ores of copper inculcated chalcanthite (CuSO$$_4$$ . 5H$$_2$$O), atacamite (Cu$$_2$$Cl(OH)$$_3$$), cuprite (Cu$$_2$$O), copper glance (Cu$$_2$$S) and malacite (Cu$$_2$$(OH)$$_2$$CO$$_3$$). However, 80% of the world copper production comes from the ore of chalcopyrite (CuFeS$$_2$$). The extraction of copper from chalcopynite involves partial roasting, removal of iron and self-reduction.
In self-reduction, the reducing species is
S
O$$^{2-}$$
S$$^{2-}$$
SO$$_2$$

Explanation

In the self-reduction step,

Cu$$_2$$S + $$\frac{3}{2}$$O$$_2$$ $$\to$$ Cu$$_2$$O + SO$$_2$$

Cu$$_2$$S + 2Cu$$_2$$O $$\to$$ $$\mathrm{\mathop {6Cu(l)}\limits_{Blister\,copper} }$$ + SO$$_2$$

In the reaction, the oxidation number of sulphur (S$$^{2-}$$) changes to (S$$^{4+}$$) so, S$$^{2-}$$ is the reducing agent.

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