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NEET 2007

Exam: NEET
Year: 2007
Subject: Chemistry
Chapter: General Principles and Processes of Isolation of Metals

NEET 2007 · Chemistry · General Principles and Processes of Isolation of Metals

Which of the following statement, about the advantage of roasting...

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

Options

AThe $\Delta \mathrm{G}_f^{\text{o }}$ of the sulphide is greater than those for $\mathrm{CS}_2$ and $\mathrm{H}_2 \mathrm{ S} .$
BThe $\Delta \mathrm{G}_f^0$ is negative for roasting of sulphide ore to oxide
CRoasting of the sulphide to the oxide is thermodynamically feasible
DCarbon and hydrogen are suitable reducing agents for metal sulphides

Correct answer

A. The $\Delta \mathrm{G}_f^{\text{o }}$ of the sulphide is greater than those for $\mathrm{CS}_2$ and $\mathrm{H}_2 \mathrm{ S} .$

Step-by-step solution

The sulphide ore is roasted to oxide before reduction because the

\Delta \mathrm{G}

of most of the sulphides are greater than those of

\mathrm{CS}_2

and

\mathrm{H}_2 \mathrm{~S}

, therefore neither

\mathrm{C}

nor

\mathrm{H}

can reduce metal sulphide to metal. Further, the standard free energies of formation of oxide are much less than those of

\mathrm{SO}_2

. Hence oxidation of metal sulphides to metal oxide is thermodynamically favourable.

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