Homemade oxygen - Oxygen sample
Hydrogen peroxide, when exposed to light, will slowly decompose into water and oxygen (2H²O² -> 2H²O + O²). You can speed this up with manganese dioxide; I've been collecting these tubes of oxygen by dropping oxidized chips of Mn into peroxide, with the tube upside-down over it such that the oxygen will displace the peroxide and fill the tube. The manganese isn't consumed and is simply a catalyst.
The one in the test tube on the left is the youngest. A photograph of the oxygen bubbling through the peroxide during its making is planned to represent oxygen in my WIP periodic table poster:
Source: Self-made
Date of Acquisition: 24 April 2026 (poster sample)











