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Which of the following statements regarding why sulphide ores are roasted before reduction is incorrect?

1. The standard Gibbs free energy of formation of the sulphide is higher than that of CS2 and H2S.
2. The Gibbs free energy change for converting a sulphide ore into its oxide by roasting is negative.
3. Roasting a sulphide ore to the corresponding oxide is thermodynamically possible.
4. Carbon and hydrogen are appropriate reducing agents for the reduction of metal sulphides.

Correct answer: Carbon and hydrogen are appropriate reducing agents for the reduction of metal sulphides.

Solution

Option D is correct because carbon and hydrogen can effectively reduce metal sulphides to their respective metals, making them suitable reducing agents in the process.

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