Question

Write the chemical equation for the following reaction:
Cinnabar is heated in the presence of air.

Answer 1

\[\ce{\underset{\text{Cinnabar}}{HgS}+\underset{\text{Oxygen from air}}{3O2}->\underset{\text{Mercury(ll) oxide}}{2HgO}+\underset{\text{Sulphur dioxide}}{2SO2}}\]

\[\ce{\underset{\text{Mercury(ii) oxide}}{2HgO}->\underset{\text{Mercury metal}}{2Hg}+\underset{\text{Oxygen gas}}{O2}}\]

In the above reaction when cinnabar is heated in the presence of oxygen, it is reduced to produce pure mercury metal.