metals and non-metals — Science STD 10 — Question

Metals low in the reactivity series are very unreactive. The oxides of these metals can be reduced to metals by heating alone.

For example, Cinnabar $(HgS)$ is an ore of mercury When it is heated in air, it is first converted into mercuric oxide $( HgO )$ then, mercuric oxide is reduced to mercury $( Hg )$ on further heating.

$\left.2 HgS _{ S } s \right)+3 O _{2}( g ) \rightarrow 2 HgO (s)+2 SO _{2}(g)$

$2 HgO (s) \rightarrow 2 Hg (l)+ O _{2}(g)$

Thus, mercury is separated.

Similarly, copper which is found as $Cu _{2} S$ in nature can be obtained from its ore by heating in air. Here, $Cu _{2} S$ is reduced to $Cu$.

$2 Cu _{2} S (s)+3 O_{2}( g ) \rightarrow 2 Cu _{2} O (s)+2 SO _{2}( g )$

$2 Cu _{2} O (s)+ Cu_{2}S (s) \rightarrow 6 Cu (s)+ SO _{2}( g )$