Everyone, I think, knows 3 basic aggregate states of matter: liquid, solid and gaseous. We encounter these states of matter every day and everywhere. Most often they are considered on the example of water. The liquid state of water is most familiar to us. We constantly drink liquid water, it flows from our tap, and we ourselves are 70% liquid water. The second aggregate state of water is ordinary ice, which we see on the street in winter. In gaseous form, water is also easily found in Everyday life. In the gaseous state, water is, we all know, steam. It can be seen when we, for example, boil a kettle. Yes, it is at 100 degrees that water passes from a liquid state to a gaseous state.

These are the three aggregate states of matter familiar to us. But did you know that there are actually 4 of them? I think at least once everyone heard the word " plasma". And today I want you to also learn more about plasma - the fourth state of matter.

Plasma is a partially or fully ionized gas with the same density of both positive and negative charges. Plasma can be obtained from gas - from the 3rd state of matter by strong heating. The state of aggregation in general, in fact, completely depends on temperature. The first aggregate state is the lowest temperature at which the body remains solid, the second aggregate state is the temperature at which the body begins to melt and become liquid, the third aggregate state is the most heat, at which the substance becomes a gas. For each body, substance, the temperature of transition from one state of aggregation to another is completely different, for some it is lower, for some it is higher, but for everyone it is strictly in this sequence. And at what temperature does a substance become plasma? Since this is the fourth state, it means that the transition temperature to it is higher than that of each previous one. And indeed it is. In order to ionize a gas, a very high temperature is required. The lowest temperature and low ionized (about 1%) plasma is characterized by temperatures up to 100 thousand degrees. Under terrestrial conditions, such plasma can be observed in the form of lightning. The temperature of the lightning channel can exceed 30 thousand degrees, which is 6 times more than the surface temperature of the Sun. By the way, the Sun and all other stars are also plasma, more often still high-temperature. Science proves that about 99% of the entire matter of the Universe is plasma.

Unlike low-temperature plasma, high-temperature plasma has almost 100% ionization and temperatures up to 100 million degrees. This is truly stellar temperature. On Earth, such a plasma is found only in one case - for experiments on thermo-nuclear fusion. Con-tro-whether-ru-e-may the reaction is quite complex and energy-expensive, but non-con-tro-whether-ru-e-may is enough dawn-to-men-do -was itself like a weapon of an ear of greasy power - a thermo-nuclear bomb, tested by the USSR on August 12, 1953.

Plasma is classified not only by temperature and degree of ionization, but also by density and quasi-neutrality. phrase plasma density usually means electron density, that is, the number of free electrons per unit volume. Well, with this, I think everything is clear. But not everyone knows what quasi-neutrality is. The quasi-neutrality of a plasma is one of its most important properties, which consists in the almost exact equality of the densities of its constituent positive ions and electrons. Due to the good electrical conductivity of the plasma, the separation of positive and negative charges is impossible at distances greater than the Debye length and at times greater than the period of plasma oscillations. Almost all plasma is quasi-neutral. An example of a non-quasi-neutral plasma is an electron beam. However, the density of non-neutral plasmas must be very low, otherwise they will quickly decay due to Coulomb repulsion.

We have considered very little terrestrial examples of plasma. But there are enough of them. Man has learned to use plasma for his own good. Thanks to the fourth aggregate state of matter, we can use gas-discharge lamps, plasma televisions zo-rami, electric arc-welding, lasers. Ordinary gas-discharge fluorescent lamps are also plasma. There is also a plasma lamp in our world. It is mainly used in science to study and, most importantly, to see some of the most complex plasma phenomena, including filamentation. A photo of such a lamp can be seen in the picture below:

In addition to household plasma devices, natural plasma can also often be seen on Earth. We have already talked about one of its examples. This is lightning. But in addition to lightning, plasma phenomena can be called the northern lights, “the fires of St. Elmo”, the Earth's ionosphere and, of course, fire.

Notice that both fire and lightning and other manifestations of plasma, as we call it, burn. What is the reason for such a bright emission of light by plasma? Plasma glow is due to the transition of electrons from a high-energy state to a low-energy state after recombination with ions. This process leads to radiation with a spectrum corresponding to the excited gas. This is why plasma glows.

I would also like to tell a little about the history of plasma. After all, once upon a time only such substances as the liquid component of milk and the colorless component of blood were called plasma. Everything changed in 1879. It was in that year that the famous English scientist William Crookes, investigating electrical conductivity in gases, discovered the phenomenon of plasma. True, this state of matter was called plasma only in 1928. And this was done by Irving Langmuir.

In conclusion, I want to say that such an interesting and mysterious phenomenon as ball lightning, which I wrote about more than once on this site, is, of course, also a plasmoid, like ordinary lightning. This is perhaps the most unusual plasmoid of all terrestrial plasma phenomena. After all, there are about 400 very different theories about ball lightning, but not one of them has been recognized as truly correct. Under laboratory conditions, similar but short-term phenomena were obtained by several different ways, so that the question of the nature of ball lightning remains open.

Ordinary plasma, of course, was also created in laboratories. Once it was difficult, but now such an experiment is not difficult. Since plasma has firmly entered our household arsenal, there are a lot of experiments on it in laboratories.

The most interesting discovery in the field of plasma was experiments with plasma in weightlessness. It turns out that plasma crystallizes in a vacuum. It happens like this: the charged particles of the plasma begin to repel each other, and when they have a limited volume, they occupy the space that is allotted to them, scattering into different sides. This is very similar to a crystal lattice. Doesn't this mean that plasma is the closing link between the first aggregate state of matter and the third? After all, it becomes a plasma due to the ionization of the gas, and in a vacuum, the plasma again becomes, as it were, solid. But that's just my guess.

Plasma crystals in space also have a rather strange structure. This structure can be observed and studied only in space, in a real space vacuum. Even if you create a vacuum on the Earth and place a plasma there, then gravity will simply squeeze the entire “picture” that forms inside. In space, however, plasma crystals simply take off, forming a volumetric three-dimensional structure of a strange shape. After sending the results of observations of plasma in orbit to earth scientists, it turned out that the swirls in the plasma mimic the structure of our galaxy in a strange way. And this means that in the future it will be possible to understand how our galaxy was born by studying plasma. The photographs below show the same crystallized plasma.

That's all I would like to say on the topic of plasma. I hope it intrigues and surprises you. After all, this is truly amazing phenomenon, or rather the state - the 4th state of aggregation of matter.

Any substance consists of molecules, and its physical properties depend on how the molecules are ordered and how they interact with each other. AT ordinary life We observe three aggregate states of matter - solid, liquid and gaseous.

For example, water can be in solid (ice), liquid (water) and gaseous (steam) states.

Gas expands until it fills the entire volume allotted to it. If we consider a gas at the molecular level, we will see molecules randomly rushing about and colliding with each other and with the walls of the vessel, which, however, practically do not interact with each other. If you increase or decrease the volume of the vessel, the molecules will evenly redistribute in the new volume.

Unlike gas at a given temperature, it occupies a fixed volume, however, it also takes the form of a filled vessel - but only below its surface level. At the molecular level, the easiest way to think of a liquid is as spherical molecules that, although they are in close contact with each other, have the freedom to roll around each other, like round beads in a jar. Pour liquid into a vessel - and the molecules will quickly spread and fill lower part volume of the vessel, as a result, the liquid will take its shape, but will not spread in the full volume of the vessel.

Solid has its own shape, does not spread over the volume of the containerand does not take its form. At the microscopic level, atoms are attached to each other by chemical bonds, and their position relative to each other is fixed. At the same time, they can form both rigid ordered structures - crystal lattices - and a random heap - amorphous bodies (this is precisely the structure of polymers, which look like tangled and sticky pasta in a bowl).

Three classical aggregate states of matter have been described above. There is, however, a fourth state, which physicists tend to classify as aggregate. This is the plasma state. Plasma is characterized by partial or complete stripping of electrons from their atomic orbits, while the free electrons themselves remain inside the substance.

We can observe the change in the aggregate states of matter with our own eyes in nature. Water from the surface of water bodies evaporates and clouds form. So the liquid turns into a gas. In winter, the water in the reservoirs freezes, turning into a solid state, and in the spring it melts again, turning back into a liquid. What happens to the molecules of a substance when it changes from one state to another? Are they changing? Are, for example, ice molecules different from vapor molecules? The answer is unequivocal: no. The molecules remain exactly the same. Their kinetic energy changes, and, accordingly, the properties of the substance.

The energy of the vapor molecules is large enough to scatter in different directions, and when cooled, the vapor condenses into a liquid, and the molecules still have enough energy for almost free movement, but not enough to break away from the attraction of other molecules and fly away. As it cools further, the water freezes, becoming solid, and the energy of the molecules is no longer enough even for free movement inside the body. They oscillate about one place, held by the attractive forces of other molecules.

In order to understand what the aggregate state of matter is, remember or imagine yourself in the summer near the river with ice cream in your hands. Great picture, right?

So, in this idyll, in addition to enjoyment, one can also carry out physical observation. Pay attention to the water. In the river it is liquid, in the composition of ice cream in the form of ice it is solid, and in the sky in the form of clouds it is gaseous. That is, it is simultaneously in three different states. In physics, this is called the aggregate state of matter. There are three states of aggregation - solid, liquid and gaseous.

Change in the state of aggregation of matter

We can observe the change in the aggregate states of matter with our own eyes in nature. Water from the surface of water bodies evaporates and clouds form. So the liquid turns into a gas. In winter, the water in the reservoirs freezes, turning into a solid state, and in the spring it melts again, turning back into a liquid. What happens to the molecules of a substance when it changes from one state to another? Are they changing? Are, for example, ice molecules different from vapor molecules? The answer is unequivocal: no. The molecules remain exactly the same. Their kinetic energy changes, and, accordingly, the properties of the substance. The energy of the vapor molecules is large enough to scatter in different directions, and when cooled, the vapor condenses into a liquid, and the molecules still have enough energy for almost free movement, but not enough to break away from the attraction of other molecules and fly away. With further cooling, the water freezes, becoming a solid body, and the energy of the molecules is no longer enough even for free movement inside the body. They oscillate about one place, held by the attractive forces of other molecules.

The nature of the movement and state of molecules in various aggregate states of matter can be reflected in the following table:

Aggregate state of matter	Matter properties	Distance between particles	Particle interaction	The nature of the movement	Arrangement order
	Does not retain shape and volume	Much more sizes the particles themselves		Chaotic (random) continuous. They fly freely, sometimes colliding.	Messy
Liquid	Does not retain shape, retains volume	Comparable to particle size		They oscillate around the equilibrium position, constantly jumping from one place to another.	Messy
Solid	Retains shape and volume	Small compared to the size of the particles themselves	Very strong	Continuously oscillate around the equilibrium position	In a certain order

processes in which there is a change in the aggregate states of substances, only six.

The transition of a substance from a solid to a liquid state is called melting, reverse process - crystallization. When a substance changes from a liquid to a gas, it is called vaporization, from gas to liquid - condensation. The transition from a solid state directly to a gas, bypassing the liquid state, is called sublimation, reverse process - desublimation.

• 1. Melting
• 2. Crystallization
• 3. Vaporization
• 4. Condensation
• 5. Sublimation
• 6. Desublimation

Examples of all these transitions we have seen it many times in our lives. Ice melts to form water, water evaporates to form steam. AT reverse side The vapor condenses back into water, and the water freezes back to ice. And if you think that you do not know the processes of sublimation and desublimation, then do not rush to conclusions. The smell of any solid body is nothing but sublimation. Some of the molecules escape from the body, forming a gas that we can smell. And an example of the reverse process is the patterns on the glass in winter, when the vapor in the air, freezing, settles on the glass and forms bizarre patterns.

Aggregate states substances(from the Latin aggrego - I attach, I connect) - these are states of the same substance, the transitions between which correspond to abrupt changes free energy, density and other physical parameters of matter.
Gas (French gaz, derived from the Greek chaos - chaos)- this is aggregate state of matter, in which the interaction forces of its particles filling the entire volume provided to them are negligible. In gases, the intermolecular distances are large and the molecules move almost freely.

Gases can be considered as highly superheated or low-saturated vapors. Above the surface of each liquid, as a result, there is vapor. When the vapor pressure rises to a certain limit, called the saturated vapor pressure, the evaporation of the liquid stops, since the liquid becomes the same. A decrease in the volume of saturated steam causes parts of the vapor, rather than an increase in pressure. Therefore, the vapor pressure cannot be higher. The saturation state is characterized by the saturation mass contained in 1 m3 of saturated vapor mass, which depends on temperature. Saturated steam can become unsaturated if the volume is increased or the temperature is increased. If the steam temperature is much higher than the point corresponding to a given pressure, the steam is called superheated.

Plasma is a partially or fully ionized gas in which the densities of positive and negative charges are almost the same. The sun, stars, clouds of interstellar matter are composed of gases - neutral or ionized (plasma). Unlike other states of aggregation, plasma is a gas of charged particles (ions, electrons) that electrically interact with each other at large distances, but do not have either short-range or long-range orders in the arrangement of particles.

Liquid- This is a state of aggregation of a substance, intermediate between solid and gaseous. Liquids have some features of a solid (retains its volume, forms a surface, has a certain tensile strength) and a gas (takes the shape of the vessel in which it is located). The thermal motion of molecules (atoms) of a liquid is a combination of small fluctuations around equilibrium positions and frequent jumps from one equilibrium position to another. At the same time, slow movements of molecules and their oscillations inside small volumes occur, frequent jumps of molecules violate the long-range order in the arrangement of particles and cause the fluidity of liquids, and small oscillations around equilibrium positions cause the existence of short-range order in liquids.

Liquids and solids, unlike gases, can be regarded as highly condensed media. In them, molecules (atoms) are located much closer to each other and the interaction forces are several orders of magnitude greater than in gases. Therefore, liquids and solids have a significant limited opportunities for expansion, obviously cannot occupy an arbitrary volume, but at constant ones they retain their volume, no matter in what volume they are placed. Transitions from a state of aggregation more ordered in structure to a less ordered one can also occur continuously. In this regard, instead of the concept of the state of aggregation, it is advisable to use a more broad concept- the concept of phase.

phase is the set of all parts of the system that have the same chemical composition and in the same condition. This is justified by the simultaneous existence of thermodynamically equilibrium phases in a multiphase system: a liquid with its own saturated vapor; water and ice at melting point; two immiscible liquids (a mixture of water with triethylamine), differing in concentration; the existence of amorphous solids that retain the structure of the liquid (amorphous state).

Amorphous solid state of matter is a kind of supercooled state of a liquid and differs from ordinary liquids in a significantly higher viscosity and numerical values kinetic characteristics.
Crystalline solid state of matter- this is a state of aggregation, which is characterized by large forces of interaction between the particles of a substance (atoms, molecules, ions). Particles of solids oscillate around average equilibrium positions, called nodes crystal lattice; the structure of these substances is characterized a high degree orderliness (long-range and short-range order) - orderliness in the arrangement (coordination order), in the orientation (orientation order) of structural particles, or orderliness of physical properties (for example, in the orientation of magnetic moments or electric dipole moments). The region of existence of the normal liquid phase for pure liquids, liquid and liquid crystals is limited from the side low temperatures phase transitions, respectively, to the solid (crystallization), superfluid, and liquid-anisotropic states.

A feature of hydraulic and pneumatic drives is that to create forces, moments of forces and movements in machines, these types of drives use the energy of a liquid or air or other gas, respectively.

The fluid used in a hydraulic drive is called working fluid (WF).

To understand the peculiarities of the use of RJ and gases in drives, it is necessary to recall some basic information about the states of aggregation of matter known from the course of physics.

According to modern views, aggregate states of a substance (from the Latin aggrego - I attach, connect) - are understood to be states of the same substance, transitions between which correspond to abrupt changes in free energy, entropy, density and other physical parameters of this substance.

In physics, it is customary to distinguish four aggregate states of matter: solid, liquid, gaseous and plasma.

SOLID STATE(crystalline solid state of matter) is a state of aggregation, which is characterized by large forces of interaction between particles of matter (atoms, molecules, ions). The particles of solids oscillate around the average equilibrium positions, called the nodes of the crystal lattice; the structure of these substances is characterized by a high degree of order (long-range and short-range order) - order in arrangement (coordination order), in orientation (orientation order) of structural particles or order in physical properties.

LIQUID STATE- This is a state of aggregation of a substance, intermediate between solid and gaseous. Liquids have some features of a solid (retains its volume, forms a surface, has a certain tensile strength) and a gas (takes the shape of the vessel in which it is located). The thermal motion of molecules (atoms) of a liquid is a combination of small fluctuations around equilibrium positions and frequent jumps from one equilibrium position to another. Simultaneously, there are slow movements of molecules and their vibrations inside small volumes. Frequent jumps of molecules break the long-range order in the arrangement of particles and cause the fluidity of liquids, while small fluctuations around equilibrium positions cause the existence of short-range order in liquids.

Liquids and solids, unlike gases, can be regarded as highly condensed media. In them, molecules (atoms) are located much closer to each other and the interaction forces are several orders of magnitude greater than in gases. Therefore, liquids and solids have significantly limited possibilities for expansion, obviously cannot occupy an arbitrary volume, and at constant pressure and temperature they retain their volume, no matter in what volume they are placed.

GAS STATE(from the French gaz, which, in turn, came from the Greek chaos - chaos) is an aggregate state of matter in which the interaction forces of its particles filling the entire volume provided to them are negligible. In gases, the intermolecular distances are large and the molecules move almost freely.

Gases can be thought of as highly superheated or low-saturated vapors of liquids. Above the surface of each liquid due to evaporation is vapor. When the vapor pressure rises to a certain limit, called the saturated vapor pressure, the evaporation of the liquid stops, since the pressure of the vapor and liquid becomes the same. A decrease in the volume of saturated steam causes some of the steam to condense, rather than an increase in pressure. Therefore, the vapor pressure cannot be higher than the saturation vapor pressure. The saturation state is characterized by the saturation mass contained in 1 m3 of saturated steam mass, which depends on temperature. Saturated steam can become unsaturated if the volume is increased or the temperature is increased. If the temperature of the steam is much higher than the boiling point corresponding to a given pressure, the steam is called superheated.

PLASMA A partially or fully ionized gas is called, in which the densities of positive and negative charges are almost the same. The sun, stars, clouds of interstellar matter are composed of gases - neutral or ionized (plasma). Unlike other states of aggregation, plasma is a gas of charged particles (ions, electrons) that electrically interact with each other at large distances, but do not have either short-range or long-range orders in the arrangement of particles.

As can be seen from the above, liquids are able to maintain volume, but are not able to independently maintain their shape. The first property brings the liquid closer to the solid, the second - to the gas. Both of these properties are not absolute. All liquids are compressible, although much weaker than gases. All liquids resist the change in shape, the displacement of one part of the volume relative to another, although less than solids.