Oxygen gas characteristics

Oxygen gas characteristics

Oxygen gas (O₂) has a boiling point of −183°C at normal atmospheric pressure. If the pressure is increased, the boiling point will also increase. At normal temperature O₂ is therefore only available in gas form. Liquid oxygen is light blue without odour; the density of the liquid is 1.15 × 10³ kg/m³ at boiling point, while the density of the gas is 1.36 kg/m³ at 15°C and normal atmospheric pressure. One litre of liquid oxygen will therefore expand 820 times when changing phase to gas at 15°C.

Liquids with boiling point below −100°C are commonly called cryogenic liquids. Handling cryo-genic liquids involves certain elements of risk:

·  Extremely low temperature can result in frost injures on the skin when handling; the cold gas may also cause internal injuries

·  Materials that come into contact with the liquid easily become brittle

·  There is a danger of explosion when uncontrolled transformation from liquid to gas is allowed to occur in closed volumes.

By itself, O₂ is inflammable but oxygen supports a fire and is normally the limiting factor for fire development. If much oxygen is available in the atmosphere, only a small spark can create an explo-sive fire. Care should therefore be taken when handling oxygen gas.