Question

What changes takes place when Cinnabar (HgS) is heated in air for a long enough time?

Answer 1

cinnabar[HgS] is heated in air to get oxide of the mercury which is then decomposed to pure metal on heating.
Chemical equation:
2HgS  +  3O2  -------------> 2HgO + 2SO2
2HgO ------------> 2Hg +O2

Answer 2

Answer:

Cinnabar (HgS) is the ore of mercury. Cinnabar (HgS) when heated in the air turns HgS into HgO (mercury oxide or mercuric oxide) accompanied by the liberation of sulphur dioxide.

2HgS + 3O2 → 2HgO + 2SO2

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