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 be reduced to metal at all
B. no reducing agent is found suitable for reducing a sulphide ore.
C. the Gibbs free enegry of formation of most sulphides are greater than half fro `CS_(2)`.
D. a metal oxide is genarally less stable than the metal sulphide.

Answer

C

Explanation

The Gibbs free enegry of most sulphides are greater than that for `CS_(2)`. In fact, `CS_(2)` is an endothermic compound. Therefore, the `Delta_(f)G^(@)` of `M_(x)S` is not compensted. So reduction of `m_(x)S` is difficult. Hence it is common partice to roast sulphide ores to corresponding oxides prior to reduction.