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Grade upto college level Physical Chemistry

. Cinnabar (HgS) abd Galena (PbS) on roasting often give their respective metals but Zinc blende (ZnS) does not. Why?

Profile image of aditya kashyap
12 Years agoGrade upto college level
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2 Answers

Profile image of Gaurav
11 Years ago
Hello Student
On roasting sulphides are partly converted to their respective oxides. Since the oxides of lead and mercury are unstable, these bring about the reduction if their respective sulphides to the corresponding metals.
PbS + 2PbO → 3Pb + SO2
Unstable
HgS + 2HgO → 3Hg + SO2
Unstable
However, zinc oxide is stable and it does not reduce ZnS to Zn.
Profile image of Sonali
8 Years ago
On roasting all these sulphides are partly converted into their respective oxides. Since the oxides of mercury and lead are unstable while that of zinc is stable therefore oxides of mercury and lead bring about the reduction of their respective sulphides to the corresponding metals but ZnO does not reduce ZnS to Zn metal.

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