Uses of O2

The element oxygen makes up one-fifth of Earth's atmosphere, 50 percent of Earth's crust and 90 percent of Earth's water. This colorless, odorless and tasteless element has the chemical symbol "O", an atomic number of 8, and an atomic weight of 15.9994. It's a gas under normal atmospheric conditions but liquefies at minus 297 degrees Fahrenheit. Discovered in 1774, O2 has proven to be one of the most useful elements on Earth.

Life Support

• Oxygen's most important use is supporting life. All multicellular and most single-celled animal organisms on Earth require oxygen for respiration. Fortunately, oxygen is a byproduct of plant respiration and the supply is assured. Oxygen therapy is a common medical practice for patients having trouble breathing. Supplying pure oxygen relieves stress on the lungs and heart and speeds recovery from surgery, heart attacks and infections. Hyperbaric oxygen therapy supplies pure oxygen to patients inside a pressure chamber for treatment of gangrene and stubborn skin infections.

Oxygen Combustion

• Oxygen is essential for supporting combustion. Without oxygen, nothing can burn.

  Steelmaking is essentially a combustion process that uses oxygen to burn carbon with iron ore to separate out the iron. Oxygen then is used to burn impurities out of the iron to produce steel. In fact, steelmaking is the biggest industrial use for pure oxygen. Oxygen's ability to enhance combustion is critical to welding and cutting of metals, as well. Pure oxygen combined with combustible gases such as acetylene or hydrogen in a torch will produce temperatures of up to 5,500 degrees Fahrenheit, sufficient to weld or cut most metals. Oxygen also is used for rocket fuel, either in liquid form or as a solid compound that releases its oxygen when heated.

Oxygen in Chemistry

• Oxygen is a very reactive element, capable of forming compounds with nearly all of the other elements. The chemical industry uses huge volumes of oxygen for chemical synthesis reactions that produce literally thousands of compounds. A leading chemical use for oxygen is refining crude oil into acetylene, ethylene, propane, gasoline, kerosene and other petroleum products. By heating crude oil, a hydrocarbon, to specific temperatures with a carefully controlled amount of oxygen, the complex hydrocarbon molecules of crude oil are "cracked" apart to produce other products having a simpler chemical structure.

Purifying Agent

• Oxygen is a purifying agent. It helps turn sewage into pure water. Treatment plants pump pure oxygen through the sewage to increase the rate at which sewage bacteria break down organic waste materials. Oxygen normally occurs as a molecule made up of two oxygen atoms, but it has an allotropic form called ozone, a molecule of three atoms that has a pungent odor associated with electrical sparks. Ozone is a gas that's a stronger oxidizing agent than regular oxygen and is used to purify water by destroying bacteria and viruses and oxidizing metals. Ozone is used to destroy odor molecules in air and on surfaces and to sterilize medical and food processing equipment. Ozone in nature exists in the stratosphere and blocks most of the ultraviolet radiation emitted by the sun.