Oxygen is a good combustion promoter and can burn with all combustible materials. With combustible gases, such as oxygen, acetylene, methane, gas, natural gas, etc., mixed in a certain proportion, it is very easy to explode. The higher the purity of oxygen, the greater the pressure and the more dangerous it is. All kinds of oil contact with compressed oxygen gas, easy to spontaneous combustion. Clothes and textiles filled with oxygen will burn at the sight of fire.

1. The universality of existence. The universality of oxygen in nature is unmatched by any element. It exists in the air as a free state, with a volume ratio of 20.93, and in water, various minerals and rocks, as well as in all animals and plants as a combined state.

2. General physical properties of oxygen. Oxygen is a colorless, tasteless and odorless gas with a chemical symbol of 0 and a molecular weight of 31.9988. It is heavier than air, density under standard state is 1429kg, index atmospheric pressure under normal pressure, liquefaction temperature is 1.429kg, liquid oxygen system is sky blue, transparent and easy to flow liquid. The solidification temperature is 1218.4c and the crystal is blue solid. A small amount of oxygen can be dissolved in water, and the volume of dissolved oxygen is 4.9%. Oxygen is magnetic.

3. Oxygen has great chemical activity. The oxidation reaction of oxygen combined with other substances to form oxides can be carried out anytime and anywhere. The oxidation reaction of pure oxygen in the oxygen making equipment is very fierce, and a large amount of heat is emitted at the same time, reaching a very high temperature.