A colorless gas without smell, oxygen is slightly soluble in water and a little heavier than air. By cooling to -183 °C, oxygen turns into a transparent bluish liquid with the density exceeding that of water. Oxygen reacts with all elements excerpt for inert gases and forms a class of compounds called oxides.
Oxygen is a typical oxidizer: when the gas concentration in the air is 30% or higher, such atmosphere conditions intensive burning of practically all substances. Oxygen provides environment for various metals, nonmetals, and complex compounds burning, such as hydrocarbon, sulfur, magnesium, ferrum, and hydrogen sulfide. These properties predetermined a wide application of the gas in various industries.