What is liquid oxygen: general information

Oxygen is the most common element on the planet. It is present in the water, the earth's crust, the air and in the organisms of living beings, actively participating in many metabolic processes. In nature, it usually exists as a gas, and in industry it is often used as a liquid. How does liquid oxygen behave? What properties does it have and where is it used?

Oxygen gas

Oxygen is one of the most important elements on the planet. It participates in the process of respiration, in the metabolism of living organisms, and also in the circulation of substances in the biosphere. In addition, it contributes to the decay and decomposition of organic residues.

Under normal conditions, it is a colorless gas that has no taste or smell. It is heavier than air and difficult to dissolve in water. In chemical terms, it is very active and is able to form compounds with almost all elements.

In the free state as O molecules2consisting of two atoms of oxygen, it is in the atmosphere.Due to this structure, the element is also called “oxygen”, but it can exist in other variations. Under certain conditions, its atoms can form "tri-oxygen" with the molecule O3,which is a blue ozone gas with a specific odor.

In the atmosphere, the oxygen content is about 21% by mass, in the earth's crust its share is much higher and is about 47% by mass. The element is part of more than one and a half thousand different rocks and minerals, most of which are silicates. There it is present in the form of compounds. In water, its content reaches 85%, and this is not surprising, because the oxygen atoms form water together with the element by hydrogen.

oxygen element

Liquid oxygen

Like other substances, oxygen can be in various states of aggregation. To turn a gas into a solid or liquid, it must be cooled strongly. With a pressure of 51 atmospheres, it becomes liquid already at -119 ° C. At normal pressure, the transformation only occurs at -183 ° C. Cooling to a temperature of -220 ° C, it hardens, forming light blue snow-like crystals.

In the liquid state, the oxygen is colored blue and enhances some properties of the gaseous substance.So, it behaves more aggressively in chemical reactions, and also becomes a strong paramagnetic and can be attracted by a magnet.

oxygen in the form of a liquid

It boils only at -183 ° C, and melts at +219 ° C. Due to its resistance to such low temperatures, liquid oxygen has cryogenic properties and can be used as a refrigerant. Under normal conditions, it evaporates quickly, turning into gas. At the same time, it intensively absorbs heat and cools the surrounding air, which is why a halo of fog appears next to it. During evaporation, the volume of oxygen increases several hundred times. So, 1 cm3fluid forms almost 800 cm3gas.

Chemical properties

Oxygen gas is an oxidizing agent. By itself, it is incombustible, but it supports the combustion process well, and, at considerable concentration and high temperatures, is explosive.

With active substances (for example, alkali metals), it can react even at room temperature and at ordinary concentrations in the air, forming oxides with them. The result is clearly visible on many metals, on which it manifests itself in the form of corrosion.

Liquid oxygen also has strong oxidizing properties. Many of the substances impregnated with it are flammable and burn with the release of energy and heat. Cotton, paper, wood, coal and some other materials may explode.

burning paper


The most common and easy to obtain source of oxygen is air. In addition, it is inexhaustible and is present in our lives everywhere. To get the necessary substances out of it, it is liquefied, and then divided into liquid nitrogen and oxygen.

Another way to get a liquid is to condense it out of gas. To do this, it is enough to lower the copper coil into a container with liquid nitrogen, and then pass gaseous oxygen through the coil. The nitrogen temperature is lower than that of oxygen, therefore, passing through a copper tube, the gas will condense and turn into a liquid. At the same time on the surface of the coil formed a small layer of snow.


The ability of liquid oxygen to oxidize other substances and enhance combustion is valued in many areas of production. At the end of the 19th – mid-20th century, the Oxyliquite explosive was manufactured from it, which was used in the mining industry to undermine the rock and also as a weapon in World War II.

oxygen fuel

Today it is more often used in medicine, pharmaceuticals, metallurgy, glass, chemical, paper and other types of industry. It produces various useful compounds, such as titanium oxide, which is involved in the manufacture of paint and varnish products, paper and plastics. In the manufacture of glass it is needed to maintain the heat in the furnaces, as well as to reduce the amount of nitric oxide entering the atmosphere. In space aviation, liquid oxygen is one of the components of rocket fuel, where it is used as an oxidizing agent, and hydrogen or kerosene acts as the fuel itself.

In medicine and pharmaceuticals, too, is not without it. Liquid oxygen is a component of bioreactors, and is also used as an additive to enzymes. In medicine, it is necessary for anesthesia, the preparation of oxygen baths and cocktails, the treatment or alleviation of the state during intoxication, asthma and other ailments. Here it is most often not used directly as a liquid, but as a source of gaseous oxygen.

Storage and Precautions

Liquid oxygen does not ignite and does not explode on its own, it is not toxic to humans and not harmful to the environment.However, the active reaction in chemical processes, as well as the cryogenic effect, make it not a completely safe substance.

liquid oxygen

When working with him you need to keep away lubricating, combustible and flammable materials, as well as always use gloves and clothing. Very low temperature oxygen can easily damage the skin and can lead to frostbite, injury and death of living cells. If the fluid covers a large part of the body, it can even be fatal.

Technical and medical liquid oxygen store Dewar vessels, which are made primarily of steel or aluminum. These are cylindrical containers with double walls, between which walls there is a vacuum cavity, as well as heat-insulating materials. They work on the principle of thermoses, well keeping the liquid inside.

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