Answer:
In cells, oxygen is needed for aerobic respiration, which allows for the extraction of energy from ingested foods. Thus supplemental oxygen at home and in hospitals is vital for those with breathing disorders such as emphysema.
Compressed oxygen tanks are used by mountaineers at high elevations to counteract the decreased O2 pressure at these altitudes.
Supplemental oxygen is needed for surgical patients intentionally rendered paralyzed for medical procedures, in which "heart-lung machines" keep their vital functions going.
Oxygen can be used as a sterilizing agent to kill certain anaerobic bacteria that are killed by sufficient exposure to the gas.
Industrial Uses of Oxygen:
Oxygen is needed for the reaction that converts carbon to carbon dioxide gas in steel working, which takes place under high temperatures in a blast furnace. The carbon dioxide produced allows for the reduction of iron oxides into more pure iron compounds.
Oxygen is used in other applications involving metal and requiring high temperatures, such as welding torches.
Aerospace Uses of Oxygen:
In liquid form, oxygen is used widely as an oxidizing agent for use in missiles and rockets, where it reacts with liquid hydrogen to produce the terrific thrust needed for take-off. Astronaut spacesuits include a nearly pure form of oxygen.
Oxygen is used to degrade hydrocarbon compounds, which are broken apart by heating them. This is used to create combustion that usually liberates water and carbon dioxide, but can also produce the hydrocarbons acetylene, propylene and ethylene.
Oxygen is used in sewage-treatment and water-purification plants. It is forced through water to increase the production of bacteria that metabolize waste products in the water.
Oxygen gas (O2) is needed to produce energy in things not linked to an electrical supply of their own, such as generators and vehicles (e.g., ships, airplanes and cars).