Question

Cinnabar is an ore of a metal ‘X’. When this ore is heated in air, it is first converted into oxide of ‘X’ (XO) and then reduced to metal ‘X’ on further heating.

Identify metal ‘X’ and write chemical equations for the reactions that occur in the above processes.

Answer 1

The metal ‘X’ in Cinnabar (HgS) is Mercury (Hg).

Roasting of Cinnabar (HgS) to Mercury (II) |Oxide (HgO): Upon heating cinnabar in air, a reaction occurs with oxygen, yielding mercury(I) oxide and sulfur dioxide.

\[\ce{2HgS_{(s)} + 3O2_{(g)} -> 2HgO_{(s)} + 2SO2_{(g)}}\]

Reduction of Mercury(l) Oxide to Mercury Metal: on additional heating at approximately 300°C, mercury(I) oxide decomposes to produce mercury metal and oxygen vapor.

\[\ce{2HgO_{(s)} -> 2Hg_{(l)} + O2_{(g)}}\]