A sulphide ore like `ZnS` is first roasted into its oxide prior to reduction by carbon because:

Options

A. A sulphide ore cannot be reduced to metal at all
B. No reducing agent is found suitable for reducing a sulphide ore
C. The Gibb.s free energy of formation of most sulphides are greater than that for `CS_(I)`
D. A metal oxide is generally less stable than the metal sulphide

Answer

C

Explanation

The Gibb.s free energy of most sulphides are greater than that for `CS_(2)`. In fact, `CS_(1)` is an endothermic compound. Therefore, the `Delta_(r)G^(Θ)` of M, S is not compensated. So reduction of M,S is difficult. Hence it is common practice to roast sulphide ones to corresponding oxides prior to reduction.