A1.2.3 Oxygen


Oxygen is a chemical element, with the chemical symbol of 0. The most stable form is 02, dioxygen, which is formed by plants during photosynthesis.

Oxygen accounts for approximately 20% of the atmosphere. It is also present in the earth’s crust and is contained within all water molecules.

Uptake of 02 in air through respiration (breathing) is essential for all aerobic life forms.

Oxygen is also important when present as ozone (O3). At low level atmosphere ozone is an air pollutant that can have harmful effects on animals and humans. However, when ozone is present in the upper atmosphere it filters out potentially harmful UV (Ultraviolet) rays and almost forms a protective bubble around the earth. Certain human activities result in the release of ozone deleting substances, which have created holes in the ozone layer. These allow UV rays in, which bounce around and may not be released, causing global warming. This is discussed in more detail later on in this course.


Industrial Applications:

Oxygen is used in medical applications, where oxygen therapy is used to treat conditions such as emphysema and pneumonia. It is also used for recreational purposes, such as scuba diving.

Commercially produced oxygen is used during smelting of iron ore and during various chemical manufacturing processes.