Oxygen Cycle Steps and Facts

It’s a reactive element found in water, most rocks and minerals, and a wide range of organic compounds. It is a colourless, odourless, and tasteless diatomic gas that makes up 21% of the atmosphere. It is widely used in industry and is essential for aerobic respiration and almost all combustion processes.

Definition

Oxygen is a chemical element with the atomic number 8 and the symbol O. It’s a highly reactive nonmetal and oxidizer that produces oxides easily with most elements and other compounds. In the periodic table, it belongs to the chalcogen group. Oxygen is the most plentiful element on Earth and the third most abundant element in the universe, behind hydrogen and helium. Two atoms of the element join together at ordinary temperature and pressure to generate dioxygen, a colourless and odourless diatomic gas with the formula O₂. Although the percentage of diatomic oxygen gas in the Earth’s atmosphere has fluctuated greatly over time, it today makes up 20.95 percent of the atmosphere. Over half of the Earth’s crust is made up of oxygen in the form of oxides.

Michael Sendivogius isolated oxygen before 1604, although it is widely assumed that Carl Wilhelm Scheele in Uppsala in 1773 or earlier and Joseph Priestley in Wiltshire in 1774 independently found the element. Priestley is frequently accorded first priority because his work was the first to be published. Oxygen, on the other hand, was referred to as “dephlogisticated air” by Priestley, who did not consider it a chemical element. In 1777, Antoine Lavoisier invented the word oxygen after discovering oxygen as a chemical element and correctly describing its role in combustion.

Oxygen cycle

The transfer of oxygen through the atmosphere (air), Biosphere (plants and animals), and Lithosphere (the earth’s crust) is referred to as the oxygen cycle. The oxygen cycle depicts how free oxygen is produced and used in each of these environments. The oxygen cycle is the biogeochemical cycle of oxygen atoms in ions, oxides, and molecules between different oxidation states via redox processes inside and between the planet’s spheres/reservoirs. Because it is a major product or reactant of many biogeochemical redox processes within the cycle, the word oxygen in the literature usually refers to the most common oxygen allotrope, elemental/diatomic oxygen (O₂). The oxygen cycle’s processes are classified as biological or geological, and they are rated as either a source (O₂ production) or a sink (O₂ consumption) (O₂ consumption).

Stages of the oxygen cycle

The oxygen cycle includes the following steps:

Stage 1: As a by-product of photosynthesis, all green plants release oxygen into the atmosphere.

Stage 2: All aerobic organisms need free oxygen for respiration.

Stage 3: Animals emit carbon dioxide, which plants re-absorb during photosynthesis. The amount of oxygen in the atmosphere has reached a state of equilibrium.

Production of oxygen

Two principal processes remove 100 million tonnes of O₂ from the air for industrial usage each year. The most common method is fractional distillation of liquefied air, with N₂ distilling as a vapour and O₂ remaining as a liquid.

Passing a stream of clean, dry air through one bed of identical zeolite molecular sieves absorbs nitrogen and produces a gas stream that is 90% to 93 percent O₂ is the other principal way of creating O₂ . Simultaneously, nitrogen gas is released from the other nitrogen-saturated zeolite bed by lowering the chamber operating pressure and directing part of the oxygen gas from the production bed through it in the opposite flow direction. The operation of the two beds is switched after a predetermined cycle time, allowing for a constant supply of gaseous oxygen to be fed through a pipeline. Pressure swing adsorption is the term for this. These non-cryogenic processes are increasingly being used to obtain oxygen gas (see also the related vacuum swing adsorption).

Water can be electrolyzed to produce molecular oxygen and hydrogen, as well as oxygen gas. DC electricity is required; if AC is used, the gases in each leg will be hydrogen and oxygen in an explosive 2:1 ratio. Electrocatalytic O₂ evolution from oxides and oxoacids is a comparable technique. Chemical catalysts can also be utilised, such as in chemical oxygen generators or oxygen candles, which are part of the life-support equipment aboard submarines and are still standard equipment on commercial planes in the event of a depressurization emergency. Another way for separating air is to use high pressure or an electric current to force air to dissolve through ceramic membranes made of zirconium dioxide, resulting in practically pure O₂ gas.

Interesting facts about oxygen

1. Oxygen is an atomic number eight element with the chemical symbol O. Eight protons and eight electrons make up oxygen.

2. On the periodic table, oxygen is categorised as a gas and a nonmetal, and it belongs to the chalcogen group. It has a density of 1.429g/L and an atomic weight of 15.999.

3. At room temperature and pressure, oxygen is made up of two oxygen atoms that combine to form dioxygen (O₂), a colourless, odourless gas.

4. At room temperature, oxygen is a gas under normal conditions. It has a melting point of -218.79 degrees Celsius and a boiling point of -182.95 degrees Celsius.

5. The stable isotopes of oxygen are O-16, O-17, and O-18. With a 99.762 percent occurrence, O-18 is the most prevalent isotope of oxygen.

6. Oxygen is a highly reactive element that enjoys forming compounds with other elements, such as oxides. Helium and neon are the only two elements with which it does not form a compound. The process of oxygen interacting with other atoms to produce compounds is known as oxidation.

7. Although oxygen aids combustion and is essential for fire, it does not burn and is not flammable in and of itself.

8. Water dissolved oxygen. Fresh water has roughly 6.04 millilitres of oxygen per litre, whereas seawater has about 4.95 millilitres of oxygen per litre.

9. Oxygen is required for human life and is required for the survival of most lifeforms on Earth. It is required for animal and plant respiration. It’s in the water we drink and the air we breathe (as H₂O).

10. Around 21% of the Earth’s atmosphere is made up of oxygen. It accounts for approximately half of the Earth’s crust, making it the most common element on the planet. Oxygen is the third most plentiful element in the universe and the most abundant element in the human body, accounting for 65 percent of the mass of the body. Oxygen makes about 1% of the Sun’s mass.

Conclusion

The oxygen cycle refers to the movement of oxygen in various forms throughout nature. When it comes to uncombined elements in the atmosphere, oxygen is second only to nitrogen in terms of abundance. Plants and animals require oxygen to breathe and then release carbon dioxide into the air and water (CO₂).