Oxygen has a huge range of commercial and industrial uses, in addition to being the colorless, odorless gas humans and other animals breathe. The biggest industrial uses of oxygen are in the manufacturing of steel and a variety of chemicals, such as hydrogen peroxide, chloroethene, ethylene oxide and nitric acid.
The ethylene oxide made from oxygen is used as antifreeze in automobiles and to manufacture polyester, while chloroethene is the primary ingredient in PVC pipes and other materials. Oxygen is also mixed with acetylene to create oxyacetylene, which is used as fuel for torches as it burns at extremely hot temperatures. These oxyacetylene torches are used in a huge number of welding and metal cutting applications, while oxygen also plays a major role in plasma and laser cutting.
Pure oxygen is an odorless, colorless gas that was first discovered in 1774. It was discovered independently by two different chemists, Carl Wilhelm Scheele in Sweden and Joseph Priestly in England. The name oxygen comes from the Greek words "oxy genes" meaning acid-forming. It is thought that oxygen first appeared in the Earth's atmosphere approximately 2 billion years ago, as a result of the photosynthesis by an early species of blue-green algae.