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Question
Why is the extraction of copper from pyrites more difficult than that from its oxide ore through reduction?
Solution
The Gibbs free energy of formation (ΔfG) of Cu2S is less than that of `H_2S` and `CS_2`. Therefore, H2 and C cannot reduce Cu2S to Cu.
On the other hand, the Gibbs free energy of formation of `Cu_2O` is greater than that of `CO`. Hence, C can reduce Cu2O to Cu.
`C_(s) + Cu_2O_((s)) -> 2Cu_(s) + CO_(g)`
Hence, the extraction of copper from its pyrite ore is difficult than from its oxide ore through reduction.
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