Question
Question: A sulphide ore like ZnS is first roasted into its oxide prior to reduction by carbon because :...
A sulphide ore like ZnS is first roasted into its oxide prior to reduction by carbon because :
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 CS2.
D
A metal oxide is generally less stable than the metal sulphide.
Answer
The Gibb’s free energy of formation of most sulphides are greater than that for CS2.
Explanation
Solution
The Gibb’s free energy of most sulphides are greater than that for CS2. In fact, CS2 is an endothermic compound. Therefore, the DfG0 of MxS is not compensated. So reduction of MxS is difficult. Hence it is common practice to roast sulphide ores to corresponding oxides prior to reduction.