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NTA Abhyas JEE Main2020ChemistryGeneral Principles and Processes of Isolation of MetalsPractice

Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?

Options

  1. Athe magnitude of Δ G f o of the sulphide is greater than those for C S 2 and H 2 S
  2. Bthe Δ G f o is negative for roasting of sulphide ore to oxide
  3. Croasting of the sulphide to the oxide is thermodynamically feasible
  4. Dcarbon and hydrogen are suitable reducing agents for metal sulphides

Correct answer

D. carbon and hydrogen are suitable reducing agents for metal sulphides

Step-by-step solution

The standard free energies of formation Δ G f o of most of the sulphides are greater than those of C S 2 and H 2 S . Hence, neither carbon nor hydrogen can reduce metal sulphides to metal. The standard free energies of formation of oxides are much lower than those of S O 2 . Therefore, oxidation of metal sulphides to metal oxides is thermodynamically favourable. Hence sulphide ore is roasted to the oxide before reduction.

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