What method is used to separate the oxygen from mercury oxide

The method used to separate oxygen from mercury oxide is by strong heating. In the lab mercury oxide is placed in strong glass test tube and strong heat applied to the test tube. Mercury oxide then undergoes a decomposition reaction to produce mecury and oxygen.

Antoine Lavoisier , the father of modern chemistry is the one credited as having proved the decomposition of mercuric oxide  by heating, and that the result was production of mercury and oxygen.

A decomposition reaction is a reaction in which  a compound breaks down into two or more simpler substances.