Liquid hydrogen is one of the states of aggregation of hydrogen. There is also a gaseous and solid state of this element. And if the gaseous form is well known to many, then the other two extreme states raise questions.
History
Liquid hydrogen was obtained only in the thirties of the last century, but before that, chemistry has come a long way in mastering this method of gas storage and application.
Artificial cooling began to be used experimentally in the middle of the eighteenth century in England. In 1984, liquefied sulfur dioxide and ammonia were obtained. Based on these studies, twenty years later the first refrigerator was developed, and thirty years later Perkins filed an official patent for his invention. In 1851, on the other side of the Atlantic Ocean, John Gorey claimed the rights to create an air conditioner.
It came to hydrogen only in 1885, when the Pole Wroblewski announced in his article the fact that the boiling point of this element is 23 Kelvin, the peak temperature is 33 Kelvin, and the critical pressure is 13 atmospheres. After this statement, James Dewar tried to create liquid hydrogen inthe end of the 19th century, but he did not get a stable substance.
Physical properties
This state of aggregation is characterized by a very low density of matter - hundredths of grams per cubic centimeter. This makes it possible to use relatively small containers to store liquid hydrogen. The boiling point is only 20 Kelvin (-252 Celsius), and this substance freezes already at 14 Kelvin.
The liquid is odorless, colorless and tasteless. Mixing it with oxygen can lead to an explosion half the time. Upon reaching the boiling point, hydrogen turns into a gaseous state, and its volume increases by 850 times.
After liquefaction, the hydrogen is placed in insulated containers that maintain low pressure and temperatures between 15 and 19 Kelvin.
Hydrogen abundance
Liquid hydrogen is produced artificially and does not occur naturally. If we do not take into account aggregate states, then hydrogen is the most common element not only on planet Earth, but also in the Universe. Stars (including our Sun) are composed of it, the space between them is filled with it. Hydrogen takes part in fusion reactions and can also form clouds.
In the earth's crust, this element occupies only about a percent of the total amount of matter. Its role in our ecosystem can be appreciated by the fact that the number of hydrogen atoms is second only to oxygen in number. Almost everything on our planetreserves H2 are in a bound state. Hydrogen is an integral part of all living beings.
Use
Liquid hydrogen (temperature -252 degrees Celsius) is used in the form of a form for storing gasoline and other derivatives of oil refining. In addition, concepts of transport are currently being created that could use liquefied hydrogen as fuel instead of natural gas. This would reduce the cost of extracting valuable minerals and reduce emissions into the atmosphere. But so far, the optimal engine design has not been found.
Liquid hydrogen is actively used by physicists as a coolant in their experiments with neutrons. Since the mass of the elementary particle and the hydrogen nucleus are almost equal, the energy exchange between them is very efficient.
Benefits and obstacles
Liquid hydrogen can slow down the warming of the atmosphere and reduce the amount of greenhouse gases if used as a fuel for cars. When it interacts with air (after passing through an internal combustion engine), water and a small amount of nitrogen oxide will be formed.
However, this idea has its own difficulties, for example, the way the gas is stored and transported, as well as the increased risk of ignition or even explosion. Even with all precautions, hydrogen evaporation cannot be prevented.
Rocket fuel
Liquid hydrogen (storage temperature up to 20 Kelvin) is one of thepropellant components. It has several functions:
- Cooling engine components and protecting the nozzle from overheating.
- Providing thrust after mixing with oxygen and heating.
Modern rocket engines run on a hydrogen-oxygen combination. This helps to achieve the right speed to overcome the gravity of the earth and at the same time keep all parts of the aircraft from exposing them to excessive temperatures.
Currently, there is only one rocket that uses hydrogen as fuel. In most cases, liquid hydrogen is needed to separate the upper stages of rockets or in those devices that will do most of the work in a vacuum. There have been suggestions from researchers to use a half-frozen form of this element to increase its density.
