Question

How you will obtain the following metals: 

(a) mercury from cinnabar? 

(b) Copper from its ore copper glance?

Answer 1

(a) Cinnabar (HgS – mercury (II) sulphide or mercuric sulphide) is an ore of mercury. It is heated in air to give mercuric oxide (HgO). Mercuric oxide is further heated to get mercury. The reactions involved are,

2Hgs(s) + 3O₂ (g) \(\overset{heat}{\longrightarrow}\) 2HgO(s) + 2SO₂ (g)

2Hgs(s) \(\overset{heat}{\longrightarrow}\) 2HgO(s) + O₂ (g)

(b) Copper glance is a sulphide ore of copper (Cu₂S). So it is converted to cuprous oxide (Cu₂O) by just heating in air. Cuprous oxide is reduced to copper using carbon. The reactions involved are,

2Cu₂S(s) + 3O₂(g) \(\overset{heat}{\longrightarrow}\) 2Cu₂O(s) + 2SO₂(g)

2Cu₂S(s) + Cu₂S(s) \(\overset{heat}{\longrightarrow}\) 6Cu(s) + SO₂(g)