We explain what liquefaction is, its types and differences between physical and chemical change.Also, examples and applications.

Liquefaction is essential in the transport and storage of gases.

What is liquefaction?

Liquefaction or liquefaction is the process of physical change in which one substance in solid state or gaseous go directly to liquid state, thanks to a radical change in their physical conditions.

The term is generally used to refer to gases (that is, gas liquefaction), but its use is also common when referring to radical processes of conversion to liquid of solids that are not commonly capable of doing so.

In the case of gases, it is a process very common and of great industrial importance, in which a gaseous body is compressed to very low temperatures, forcing their particles to be linked in such a way that they acquire a temporary liquidity status.

This is the method used in the transport of most gases (since in a liquid state they are much more stable) and is the reason why the gas accumulated in the lighters is a liquid: by activating the ignition mechanism, the Pressure and some of the liquid returns to its gaseous form, allowing the spark of the lighter to ignite it and feeding a flame.

Types of liquefaction

We can use the liquefaction term in three contexts usual:

  • Gas liquefaction. It is the process of compressing gases at a low temperature to bring them to a liquid state, from which they will come out spontaneously if we decrease the pressure, or explosively if we increase their temperature.
  • Soil liquefaction. It is the consequence of seismic movements (intense tremors, even tsunamis), whose energy is such that the consistency of certain soils and make it similar to that of a heavy liquid or that of quicksand. This often triggers landslides or landslides.
  • Direct liquefaction of coal. It is a very specific use of the term, which refers to a chemical change –Non-physical, like the previous ones– known as the Pott-Broche process, which converts coal into a mixture of hydrocarbons called "synthetic crude", very similar to Petroleum. The process usually consists, roughly, of mixing the carbon with solvents at high pressures and temperatures, and then adding hydrogen to the mixture (process known as "hydrocracking").

Examples of liquefaction

Soil liquefaction is the variation in the consistency of the soil after an earthquake.

There are many examples of gas liquefaction around us: the liquid content of lighters, the gas containers of furnaces, the liquid oxygen in hospitals, the anesthetic gas used to operate, or even the natural gas liquefied with which our kitchens feed via pipes. They are all perfect examples of liquefaction of a gaseous body.

On the other hand, if we want to have examples of soil liquefaction, we can search for videos online of what happened in some of the recent large earthquakes in the region. history. The results are usually impressive.

Applications of liquefaction

Liquefaction has multiple industrial uses.

Gas liquefaction has very important applications in the industrial world, insofar as it allows the gas to be transported in a safer and more protected way, given that in its liquid condition it acquires greater stability, especially when it comes to highly combustible hydrocarbons.

In addition, given the ability of gases to be compressed into small volumes, we can put a large amount of gas in a container, thus justifying the weight and investment in its design and transportation.

Similarly, coal liquefaction and other laboratory processes allow industrial results to be obtained that would otherwise have to be sought in very specific environments on the planet, given that true crude is produced underground during a millennial process of chemical changes.

Liquefaction and condensation

If liquefaction is the transformation, by increasing pressure and decreasing temperature, of a gaseous body into a liquid.

The condensation It is the same change of state but at normal conditions of pressure and temperature, that is, condensation is a process that also involves a physical change from gas to liquid, but that occurs without the need to exert enormous pressure, but through the decrease in Energy contained in the gas particles.

This is what happens when we take a hot shower and the water steam (gas) condenses on the mirror surface (which is at a lower temperature) in the form of tiny droplets of water (liquid) that fog it up. So while they produce similar results (turning gases into liquids), we can never confuse these two different physical processes.

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