Question

Which of the following factors is of no significance for roasting sulphide ores to the oxides and not subjecting the sulphide ores to carbon reduction directly?

• A. Metal sulphides are thermodynamically more stable than $C{S}_2$
• B. $C{O}_2$ is thermodynamically more stable than $C{S}_2$
• C. Metal sulphides are less stable than the corresponding oxides
• D. $C{O}_2$ is more volatile than $C{S}_2$

Answer 1

The correct option is C Metal sulphides are less stable than the corresponding oxides

The reduction of metal sulfides by the carbon reduction process is not spontaneous as the change in Gibb's free energy ($△G$) for such a process is positive.

The reduction of metal oxides by the carbon reduction process is spontaneous as $△G$ for such a process is negative.

Thus $C{O}_2$ is more stable than $C{S}_2$ and the metal sulfides are more stable than the corresponding oxides.

Hence, the factor listed in option $C$ is of no significance.