A19 Preparation of Oxygen from Mercury(II) Oxide

Description
Oxygen is prepared by heating mercury(II) oxide, a classic technique. A smoldering wooden splint burns brightly when it is inserted into the gas over the mercury(II) oxide. Mercury forms on the walls of the test tube and distills upward during the heating.

Equation
2 HgO --> O₂ + 2 Hg

Reference