With the name of liquefaction (or liquefaction) one of the changes in the state of aggregation that matter can have is known, in particular the one that goes from a gaseous state to a liquid state. For example: the liquefaction of air, compressed natural gas, liquefied chlorine.
The process occurs due to the effect of pressure and temperature, to the extent that for all gases there is a temperature level below which, by applying a sufficiently large pressure, they can be transformed into liquids. In the same sense, no matter how great the pressure, the gas cannot be liquefied as soon as its temperature exceeds a certain level.
Discovery and Applications
The process of the change of state from gas to liquid by means of high pressures and low temperatures was discovered by Michael Faraday in 1823, and the most important subsequent studies were those of Thomas Andrews, who in 1869 discovered that each gas has a critical temperature (at a temperature above this, the gas cannot be liquefied by increasing the pressure). When compression is carried out, it happens that the speed of the molecules and the distances between them decrease until they experience the change of state.
During the 20th century, the liquefaction of gases played an indispensable role in weapons matters, especially at the time of the World Wars.
Another of the most important uses What is given to the liquefaction process is that from it the fundamental properties of gas molecules can be analyzed, for their storage. On the other hand, many liquefied gases are used in different areas of medicine in order to improve people’s quality of life.
Liquefied natural gas
Anyway, the most typical example of liquefaction is the liquefied or compressed natural gas, that is, natural gas that has been processed for transportation in liquid form. Those places where it is not profitable to build a gas pipeline or to generate electricity, appeal to the transport of fuel by this means: the gas here is transported as a liquid at atmospheric pressure and at a temperature of -162 ºC, in huge trucks that can usually be seen on the roads of most countries.
This type of gas has no color or odor and is considered relatively safe, in addition to lowering the costs of infrastructure and energy production in many projects. It should not be inhaled because it displaces oxygen, which is why it is suffocating, and can be toxic.
A liquefaction that occurs involuntarily is that which occurs when some soils are subjected to the shaking of an earthquake and they release the substances that they have in gaseous form, causing the sediment to fall and the water inside them to flow. When the liquefaction of the soil occurs, its particles go from the solid state to a state of a heavy liquid.
It is very important to analyze the character of the soil in areas prone to earthquakes, since the loss of soil resistance in these cases makes the structures mounted there unable to remain stable, and they are dragged on the mass of liquid soil.
Examples of liquefaction
- The liquefaction of air. This process is used to obtain gases such as oxygen and nitrogen in liquid state, which are then used in various applications.
- Compressed natural gas.
- The liquefied chlorine, for water purification.
- The liquefaction of helium, which is used to be used in superconducting magnets, or in matters related to magnetic resonance imaging.
- Liquid nitrogen, used in dermatology and artificial insemination.
- Lighters and carafes, which contain liquid gas obtained from liquefaction.
- Industrial waste sanitation uses different types of liquefied gases.
- Liquid oxygen, used for patients suffering from respiratory problems.
- LP gas, liquefied petroleum, used in refrigeration and air conditioning.