Liquid hydrogen is one of the aggregate states of hydrogen. The gaseous and solid state of this element is also isolated. And if the gaseous form is familiar 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 the development of this method of gas storage and use.
Artificial cooling was experimentally started in the mid-eighteenth century in England. In 1984, liquefied sulfur dioxide and ammonia were obtained. Based on these studies, the first refrigerator was developed twenty years later, and thirty years later Perkins filed an official patent for his invention. In 1851, on the other side of the Atlantic Ocean, John Gory claimed the rights to create an air conditioner.
It only came to hydrogen in 1885, when the Pole Wroblewski announced in his article 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 at the end of the 19th century, but he failed in a stable substance.
Physical properties
This aggregate state is characterized by a very low density of matter - hundredths of a gram per cubic centimeter. This makes it possible to use relatively small containers to store liquid hydrogen. The boiling point is only 20 Kelvins (-252 Celsius), and this substance freezes already at 14 Kelvins.
The liquid is odorless, colorless, and tasteless. Mixing it with oxygen can lead to an explosion in half the cases. When the boiling point is reached, hydrogen passes into a gaseous state, and its volume increases 850 times.
After liquefaction, hydrogen is placed in insulated containers in which low pressure and temperature are maintained between 15 and 19 Kelvin.
Hydrogen abundance
Liquid hydrogen is produced artificially and does not occur in the natural environment. If you do not take aggregate states into account, then hydrogen is the most common element not only on planet Earth, but also in the Universe. Stars consist of it (including our Sun), it filled the space between them. 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 estimated by the fact that the number of hydrogen atoms in quantity is second only to oxygen. On our planet, almost all of the H 2 reserves are in a bound state. Hydrogen is an integral part of all living things.
Using
Liquid hydrogen (Celsius temperature -252 degrees) is used in the form of a form for storing gasoline and other derivatives of oil refining. In addition, transport concepts are currently being developed that could use liquefied hydrogen as fuel instead of natural gas. This would reduce the cost of extracting valuable minerals and reduce emissions. But while the optimal engine design has not been found.
Liquid hydrogen is actively used by physicists as a cooler 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 effective.
Benefits and obstacles
Liquid hydrogen makes it possible to slow down the heating of the atmosphere and reduce the amount of greenhouse gases, if used as fuel for cars. When it interacts with air (after passing through an internal combustion engine), water and a small amount of nitric oxide will form.
However, this idea has its own difficulties, for example, the method of storage and transportation of gas, as well as the increased risk of ignition or even explosion. Even if all precautions are taken, the evaporation of hydrogen cannot be prevented.
Rocket fuel
Liquid hydrogen (storage temperature up to 20 Kelvin) is one of the components of rocket fuel. It has several functions:
- Cooling engine elements and protecting the nozzle from overheating.
- Providing traction after mixing with oxygen and heating.
Modern rocket engines run on a hydrogen-oxygen combination. This helps to achieve the desired speed to overcome the attraction of the earth and at the same time preserve all parts of the aircraft without exposing them to excessive temperatures.
At the moment, there is only one rocket that fully uses hydrogen as fuel. In most cases, liquid hydrogen is needed to separate the upper stages of missiles or in those devices that will spend most of the work in vacuum. Researchers have come up with suggestions to use the half-frozen form of this element to increase its density.