60. NCERT Exemplar: Long answer questions V

  

$HgS$ reacts with $O_2$ to produce mercuric oxide and sulphur dioxide. Mercuric oxide is an unstable compound and it changes into $Hg(l)$, which can be refined by crystallisationelectrolytic refiningdistillation.

 

$2HgS^{4-}+3O_2→2HgO+2SO_2$

$HgS+X→3Hg+SO_2$

 

Where X is

 

Roasting sulphide ore, such as $Zn$, produces metal oxide, which is reduced with metal sulphide ($ZnS$) or a suitable reducing agent to produce metal, which is refined by electrolytic refiningdistillationcrystallisation.

$2ZnS + 3O_2→2ZnO+2SO_2$

$2ZnO + ZnS→3Zn + SO_2$

Alternative method of reduction:

$ZnO + Y → Zn + CO$

 

Where Y is .