Question

Write chemical equation for obtaining mercury from cinnabar.

Answer 1

Chemical equation for obtaining Mercury from Cinnabar

Cinnabar is mercury(II) sulphide, \(\mathrm{HgS}\). On roasting in air it yields mercury metal.

Overall reaction (roasting):
\[ \mathrm{HgS \;+\; O_2 \;\longrightarrow\; Hg \;+\; SO_2} \]

Stepwise (often shown in textbooks):
\[ \mathrm{2\,HgS \;+\; 3\,O_2 \;\longrightarrow\; 2\,HgO \;+\; 2\,SO_2} \] \[ \mathrm{2\,HgO \;\xrightarrow{\Delta}\; 2\,Hg \;+\; O_2} \] (Mercury vapour condensed to liquid mercury.)