The aggregate state of the substance

Substance - A realistic combination of particles related to the chemical bonds and those under certain conditions in one of the aggregate states under certain conditions. Any substance consists of a set of a very large number of particles: atoms, molecules, ions that can be combined with each other in associates, also called aggregates or clusters. Depending on the temperature and behavior of particles in associates (the mutual arrangement of particles, their number and interaction in the associate, as well as the distribution of associates in space and their interaction between themselves) substance may be in two main aggregate states - crystalline (solid) or gaseous, and in transitional aggregate states - amorphous (solid), liquid crystal, liquid and vaporiform.Solid, liquid crystal and liquid aggregate states are condensed, and vapor and gaseous - highly discharged.

Phase - This is a combination of homogeneous microelands characterized by the same ordering and concentration of particles and concluded in the macroscopic volume of a substance bounded by the surface of the section. In such an understanding of the phase characteristic only for substances in the crystalline and gaseous states, because These are homogeneous aggregate states.

Metafaza - This is a combination of heterogeneous microelands, differing from each other degree of ordering of particles or their concentration and prisoners in the macroscopic volume of a substance bounded by the surface of the section. In such an understanding of metaphase characteristic only for substances located in inhomogeneous transitional aggregate states. Different phases and metaphases can be mixed between each other, forming one aggregate state, and then there is no surface of the section between them.

Usually do not share the concepts of "main" and "transient" aggregate states. The concepts of "aggregate state", "phase" and "mesophase" are often used as synonyms. It is advisable to consider five possible aggregate states for the state of substances: solid, liquid crystal, liquid, vapor-shaped, gaseous.The transition of one phase into another phase is called the first and second phase transition. Phase transitions of the first kind are characterized by:

With a hoping change in the physical grandeur describing the state of the substance (volume, density, viscosity, etc.);

A specific temperature at which this phase transition is performed

Determined by the warmth characterizing this transition, because Intermolecular ties are torn.

Phase transitions of the first kind are observed when switching from one aggregate state to another aggregate state. Phase transitions of the second kind are observed when the ordinance of particles changes within one aggregate state are characterized by:

Gradual change in the physical properties of the substance;

Changing the ordering of the particles of the substance under the action of the gradient of the external fields or at a certain temperature, called the phase transition temperature;

The warmth of the second kind of phase transitions is equal to zero.

The main difference in phase transitions of the first and second kind is that in the transitions of the first kind, the energy of the particles of the system changes, and in the case of second-kind transitions, the ordering of the particles of the system.

The transition of a substance from a solid state into liquid is called melting and characterized by a melting point. The transition of a substance from liquid to a vapor state is called evaporation and characterized by boiling point. For some substances with a small molecular weight and weak intermolecular interaction, a direct transition from a solid state in a vapor-shaped, bypassing liquid is possible. Such a transition is called sublimation. All listed processes can flow in the opposite direction: then they are called freezing, condensation, desublimation.

Substances that do not decompose when melting and boiling may be dependent on temperature and pressure in all four aggregate states.

Solid state

At a fairly low temperature, almost all substances are in a solid state. In this state, the distance between the particles of the substance is comparable to the dimensions of the particles themselves, which ensures their strong interaction and significant excess of the potential energy over the kinetic energy. The movement of the particles of the solid is limited only by insignificant fluctuations and rotations relative to the position occupied, and there are no progressive movement . This leads to internal ordering in the location of the particles. Therefore, for solid bodies, its own form, mechanical strength, constant volume (they are practically incompressible). Depending on the degree of ordering of particles, solids are divided into crystal and amorphous.

Crystalline substances are characterized by the presence of order in the location of all particles. The solid phase of crystalline substances consists of particles that form a homogeneous structure characterized by strict repeatability of the same elementary cell in all directions. The elementary cell of the crystal characterizes three-dimensional frequency in the location of the particles, i.e. Its crystal lattice. Crystal lattices are classified depending on the type of particles constituting the crystal, and on the nature of the attraction forces between them.

Many crystalline substances depending on the conditions (temperature, pressure) may have a different crystal structure. This phenomenon is called polymorphism.Well-known polymorphic modifications of carbon: graphite, fullerene, diamond, carbines.

Amorphous (shapeless) substances.This condition is characteristic of polymers. Long molecules are easily bent and intertwined with other molecules, which leads to irregularity in the location of the particles.

The difference between amorphous particles from crystalline:

isotropy - the sameness of the physical and chemical properties of the body or environment in all directions, i.e. independence of property properties;

lack of fixed melting point.

The amorphous structure has glass, melted quartz, many polymers. Amorphous substances are less stable than crystalline, and therefore any amorphous body with time can go into an energy-sharply more stable state - crystalline.

Liquid state

With increasing temperature, the energy of thermal oscillations of particles increases, and for each substance there is a temperature, starting with which the energy of thermal oscillations exceeds the bonding energy. Particles can make various movements, shifting relative to each other. They still remain in contact, although the correct geometric structure of the particles is broken - the substance exists in a liquid state. Due to the mobility of particles for a liquid state, Brownian movement, diffusion and volatility of particles are characteristic. An important property of the fluid is viscosity, which characterizes the inter-massocyant forces that prevent the free flow of fluid.

Liquids occupy an intermediate position between gaseous and solid states. More ordered structure than gas, but less than solid.

Paro - and gaseous status

Paro-gaseous state is usually not distinguished.

Gas - this is a strongly discharged homogeneous system consisting of individual molecules, far away from each other, which can be considered as a single dynamic phase.

Couples - this is a strongly discharged inhomogeneous system, which is a mixture of molecules and unstable small associates consisting of these molecules.

The molecular-kinetic theory explains the properties of the ideal gas, based on the following provisions: molecules make a continuous erratic movement; The volume of gas molecules is negligible compared to intermolecular distances; between gas molecules do not apply to attraction or repulsion; The average kinetic energy of gas molecules is proportional to its absolute temperature. Due to the insignificance of the forces of intermolecular interaction and the presence of a large free volume for gases, characteristic: high speed of thermal motion and molecular diffusion, the desire of molecules to occupy as large as possible, as well as large compressibility.

An isolated gas-phase system is characterized by four parameters: pressure, temperature, volume, amount of substance. The relationship between these parameters is described by the equation of the state of the ideal gas:

R \u003d 8.31 kJ / mol - universal gas constant.

In winter, water on the surface of the lakes and rivers freezes, turning into ice. Drinking water remains liquid (Fig. 76). Here at the same time there are two different states of water - solid (ice) and liquid (water). There is a third state of water - gaseous: Invisible water vapor is located in the air surrounding us. On the example of water, we see that substances can be in three aggregate states - solid, liquid and gaseous.

Liquid mercury can be seen in the thermometer tank. Above the mercury surface is its pairs, which are gaseous state of mercury. At temperatures -39 ° C mercury freezes, turning into a solid state.

Oxygen in the surrounding air is gas. But at a temperature of -193 ° C, it turns into a liquid. Cooling this liquid to -219 ° C, we obtain solid oxygen.

And on the contrary, iron under normal conditions solid. However, at a temperature of 1535 ° C iron melts and turns into a liquid. Above the molten gland will be gas - pairs from iron atoms.

The properties of the substance in various aggregate states are different.

Solid Under normal conditions, it is difficult to compress or stretch. In the absence of external influences, it retains its shape and volume.

Liquid Easily changes its shape. In normal conditions, it takes the shape of the vessel in which it is (Fig. 77). But in a state of weightlessness (for example, in the orbital space station), the fluid is characterized by its own - spherical - form. Small rain droplets have a spherical shape (shape of the ball).

The fluid property is easy to change its form take into account when dishes made from molten glass (Fig. 78).

The form of liquid is easy to change, but it is difficult to change it. The description of one historical experience has been preserved, in which the water tried to squeeze in this way. It was poured into the lead ball and the ball was sealed so that the water could not pour out when compressed. After that, they hit the lead ball with heavy hammer. And what? The water did not squeeze together with the ball, but leaked through its walls.

So, fluids easily change their form, but retain their volume.

Gas Does not have its own volume and does not have its own form. He always fills the entire container provided to it.

To explore the properties of gases, it is not necessary to have a gas having color. The air, for example, is blunt, and we do not see it. But with a rapid movement, being at the window of a car or train, and when the wind blows, we notice the presence of the air around us. It can be found with the help of experiments.

Lower the glass inverted upside down in the water - water will not fill the glass, as the air will remain in it. If you lower the funnel into the water connected by a rubber hose with a glass tube (Fig. 79), then the air will begin to leave it out. Gas volume can be changed. By clicking on the rubber ball, we will noticeably reduce the amount of air located on the ball.

Once in some vessel or room, gas fills them with entirely, taking both their shape and volume.

1. In which three aggregate states can any substance be? Give examples. 2. The body retains its volume, but easily changes the form. What condition is this body? 3. The body retains its shape and volume. What condition is this body? 4. What can you say about the form and volume of gas?

State of aggregation - This state of the substance at a certain temperature range and pressure is characterized by the properties: the ability (solid) or inability (liquid, gas) to maintain volume and shape; The presence or absence of a long-range (solid) or near (liquid) order and other properties.

The substance may be in three aggregate states: solid, liquid or gaseous, currently released an additional plasma (ionic) state.

IN gaseous condition The distance between atoms and molecules of the substance is large, the interaction forces are small and particles, chaotic moving in space, have a large kinetic energy exceeding potential energy. The material in the gaseous state does not have neither its form or volume. Gas fills all available space. This condition is typical for substances with low density.

IN liquid A condition is preserved only the neighboring order of atoms or molecules, when separate sections with an ordered arrangement of atoms periodically occur in the volume of substances, but the mutual orientation of these sites is also missing. The near order is unstable and under the action of thermal fluctuations of atoms can either disappear or occur again. Liquid molecules do not have a certain position, and at the same time, complete freedom of movement is not available. The material in the liquid state does not have its form, it remains only the volume. Liquid can only take part of the volume of the vessel, but freely flop over the entire surface of the vessel. Liquid state is usually considered intermediate between solid and gas.

IN solid The substance is the order of arrangement of atoms becomes strictly defined, naturally ordered, the interaction forces of particles are mutually balanced, therefore the bodies retain their shape and volume. The naturally ordered arrangement of atoms in space characterizes the crystalline state, the atoms form a crystal lattice.

Solid bodies have an amorphous or crystalline structure. For amorphous The bodies are characteristic only of the neighboring order in the location of atoms or molecules, the chaotic arrangement of atoms, molecules or ions in space. Examples of amorphous bodies are glass, pitch, var, externally in solid state, although in fact they slowly flow, like liquid. A certain melting point in amorphous bodies, in contrast to crystalline, no. Amorphous bodies occupy an intermediate position between crystalline solid bodies and liquids.

Most solids have crystal A structure that is characterized by an ordered arrangement of atoms or molecules in space. For the crystal structure, a long-range procedure is characterized when the elements of the structure are periodically repeated; With a low order, there is no correct repetition. A characteristic feature of the crystal body is the ability to preserve the form. The sign of the perfect crystal, the model of which is the spatial grille, is the symmetry property. Under the symmetry is understood as the theoretical ability of the crystalline grille of the solid body to combine with itself with a mirror reflection of its points from a certain plane, called the symmetry plane. The symmetry of the outer form reflects the symmetry of the internal structure of the crystal. The crystal structure has, for example, all metals for which two types of symmetry are characteristic: cubic and hexagonal.

In amorphous structures with a disordered distribution of atoms, the properties of the substance in different directions are the same, that is isotropic substances (amorphous) substances.

For all crystals, anisotropy is characterized. In the distance crystals between atoms are ordered, but in different directions, the degree of orderliness may be unequal, which leads to the difference in the properties of the crystal substance in different directions. The dependence of the properties of the substance of the crystal from the direction in its lattice is called anisotropy Properties. Anisotropy is manifested when measuring both physical and mechanical and other characteristics. There are properties (density, heat capacity), independent of the direction in the crystal. Most of the characteristics depends on the choice of direction.

Measure properties may have properties that have a certain material volume: dimensions - from a few millimeters to tens of centimeters. These objects with the structure, identical crystalline cell, are called single crystals.

The anisotropy of the properties is manifested in single crystals and is practically absent in the polycrystalline substance consisting of a plurality of small chaotic oriented crystals. Therefore, polycrystalline substances are called quasiizotropic.

Crystallization of polymers whose molecules can be located ordered with the formation of supramolecular structures in the form of packs, clubs (globul), fibrils, etc., occurs at a certain temperature range. The complex structure of molecules and their aggregates determines the specifics of the behavior of polymers when heated. They cannot move into a low viscosity liquid state, do not have a gaseous state. In solid form, polymers can be in glassy, \u200b\u200bhighly elastic and viscous states. Polymers with linear or branched molecules can be changed from one state to another, which is manifested in the process of polymer deformation. In fig. 9 shows the dependence of deformation on temperature.

Fig. 9 Thermomechanical amorphous polymer curve: t. c, t. t, T. p - glass transition temperatures, fluidity and early chemical decomposition, respectively; I - iii - zones of glassy, \u200b\u200bhighly elastic and viscous state, respectively; Δ. l.- Deformation.

The spatial structure of the location of the molecules determines only the glass-like state of the polymer. At low temperatures, all polymers are deformed elastically (Fig. 9, zone I.). Above the glass transition temperature t. C Amorphous polymer with a linear structure goes into a highly elastic state ( zone II.), and its deformation in glassy and highly elastic states is reversible. Heating above temperature flow t. T translates the polymer into a viscous state ( zone III). The deformation of the polymer in the viscous state is irreversible. The amorphous polymer with a spatial (mesh, sewn) structure does not have a viscous state, the temperature area of \u200b\u200bthe high-elastic state expands to the decomposition temperature of the polymer t. R. Such behavior is characteristic of rubber type materials.

The temperature of the substance in any aggregate state characterizes the average kinetic energy of its particles (atoms and molecules). These particles in bodies have in the main kinetic energy of oscillatory movements relative to the equilibrium center, where energy is minimal. When a certain critical temperature is reached, the solid material loses its strength (stability) and melted, and the fluid turns into pairs: piping and evaporates. These critical temperatures are melting and boiling temperatures.

When the crystalline material is heated at a certain temperature of the molecule, the molecule is moved so vigorously that the rigid connections in the polymer are disturbed and the crystals are destroyed - go into a liquid state. The temperature in which the crystals and liquid are in equilibrium is called a crystal melting point, or a liquid solidification point. For iodine, this temperature is 114 o C.

Each chemical element has an individual melting point. t. PL, dividing the existence of a solid and liquid, and a boiling point t. Kip, corresponding to the transition of fluid in gas. At these temperatures, substances are in thermodynamic equilibrium. The change in the aggregate state may be accompanied by a jump-shaking change in free energy, entropy, density and other physical quantities.

To describe various states in physics uses a wider conceptthermodynamic phase. The phenomena describing transitions from one phase to another are called critical.

When heating the substance undergo phase transformations. Copper when melting (1083 o C) turns into a liquid in which the atoms have only a near-melee order. With a pressure of 1 atm, copper boils at 2310 ° C and turns into gaseous copper with randomly located copper atoms. At the melting point of a saturated pair of crystal and liquid are equal.

The material is generally a system.

System - Group of substances united physicalchemical or mechanical interactions. Phase Called a homogeneous part of the system separated from other parts the physical boundaries of the section (in the cast iron: graphite + iron grains; in ice water: ice + water).Components Systems are different phases forming this system. System components - These are substances that form all phases (composite parts) of this system.

Materials consisting of two or more phases are dispersedsystems. The dispersedystems are separated by evil, the behavior of which resembles the behavior of liquids, and gels with the characteristic properties of solids. In the ash dispersion medium in which the substance is distributed is liquid, the solid phase prevails in the gels. The gels are semi-crystalline metal, concrete, a solution of gelatin in water at low temperatures (at high temperature, gelatin goes into a sol). Hydrosole is called dispersion in water, aerosol - dispersion in the air.

Status diagrams.

In the thermodynamic system, each phase is characterized by parameters such as temperature T., concentration from and pressure R. To describe phase transformations, a single energy characteristic is used - the free energy of Gibbs ΔG. (thermodynamic potential).

Thermodynamics when describing transformations is limited to the consideration of the status of equilibrium. Equilibrium condition The thermodynamic system is characterized by the immutability of thermodynamic parameters (temperature and concentration, since in technological processing R\u003d const) in time and the absence of energy flows and substances in it - with constant external conditions. Phase equilibrium - the equilibrium state of the thermodynamic system consisting of two or more phases.

For a mathematical description of the conditions of equilibrium system exists phase ruleGibbs derived. It binds the number of phases (f) and components (K) in the equilibrium system with a system variance, i.e., the number of thermodynamic degrees of freedom (C).

The number of thermodynamic degrees of freedom (variability) of the system is the number of independent variables as internal (the chemical composition of the phases) and external (temperature), which can be given various arbitrary (in some interval) so that new phases do not disappear and did not disappear .

Gibbs phase equation:

C \u003d K - F + 1.

In accordance with this rule in the system of two components (K \u003d 2), the following variants of freedom are possible:

For a single-phase state (F \u003d 1) C \u003d 2, i.e., you can change the temperature and concentration;

For a two-phase state (F \u003d 2) C \u003d 1, i.e., you can change only one external parameter (for example, temperature);

For a three-phase state, the number of degrees of freedom is zero, i.e. it is impossible to change the temperature without disrupting the equilibrium in the system (the system is nonvariant).

For example, for pure metal (K \u003d 1) during crystallization, when there are two phases (F \u003d 2), the number of freedom degrees is zero. This means that the crystallization temperature cannot be changed until the process is completed and one phase will remain - solid crystal. After the end of the crystallization (F \u003d 1), the number of freedom degrees is 1, so it is possible to change the temperature, that is, cooling the solid, without disturbing the equilibrium.

The behavior of systems, depending on temperature and concentration, is described by the status diagram. The water status diagram is a system with one component H 2 O, therefore the largest number of phases, which can be at the same time in equilibrium, equal to three (Fig. 10). These three phases are liquid, ice, steam. The number of freedom of freedom in this case is zero, i.e. It is impossible to change nor pressure nor the temperature so that none of the phases disappear. Ordinary ice, liquid water and water vapor can exist in equilibrium simultaneously at a pressure of 0.61 kPa and a temperature of 0.0075 ° C. The coexistence point of the three phases is called a triple point ( O.).

Curve OS. Separates the areas of steam and liquid and is the dependence of the pressure of saturated water vapor on temperature. The OS curve shows that interrelated values \u200b\u200bof temperature and pressure in which liquid water and water steam are in equilibrium with each other, so it is called the equilibrium fluid curve or the boiling curve.

Figure 10 Water status diagram

Curve OV Separates the liquid area from the ice area. It is an equilibrium curve solid state - liquid and called melting curve. This curve shows those interrelated pairs of temperature and pressure values \u200b\u200bin which ice and liquid water are equilibrium.

Curve Oa. It is called the sublimation curve and shows interrelated pairs of pressure and temperature values, in which ice and water vapor are in equilibrium.

The status diagram is a visual way of representing the areas of the existence of various phases depending on external conditions, for example, pressure and temperature. The status diagrams are actively used in the material science at different technological stages of obtaining the product.

The liquid differs from the solid crystalline body with small viscosity values \u200b\u200b(internal friction of molecules) and high yield values \u200b\u200b(value, reverse viscosity). The fluid consists of a variety of molecules units, inside which the particles are located in a certain order, like order in crystals. The nature of structural units and inter-partic interaction determines the properties of the fluid. Liquid differences: monoatomic (liquefied noble gases), molecular (water), ionic (molten salts), metal (molten metals), liquid semiconductors. In most cases, the liquid is not only an aggregate state, but also a thermodynamic (liquid) phase.

Liquid substances most often represents solutions. Solutionuniform, but is not a chemically pure substance, consists of a dissolved substance and solvent (solvent examples - water or organic solvents: dichloroethane, alcohol, carbon tetrachloride, etc.), therefore it is a mixture of substances. An example is a solution of alcohol in water. However, solutions are also mixtures of gaseous (for example, air) or solid (metal alloys) substances.

When cooled under conditions of a low rate of formation centers of crystallization and a strong increase in viscosity, a glassy state may occur. Glasses are isotropic solid materials obtained by the supercooling of molten inorganic and organic compounds.

Many substances are known, the transition of which from the crystalline state into isotropic liquid is carried out through an intermediate liquid crystal state. It is characteristic of substances whose molecules have the shape of long rods (sticks) with an asymmetric structure. Such phase transitions accompanied by thermal effects cause a jump-like change of mechanical, optical, dielectric and other properties.

Liquid crystalsLiquid, can take the form of an elongated drop or a vessel shape, have high fluidity, capable of merging. They were widely used in different fields of science and technology. Their optical properties are highly dependent on small changes in external conditions. This feature is used in electro-optical devices. In particular, liquid crystals are used in the manufacture of electronic watches, visual equipment, etc.

The main aggregate states are plasma- Partially or completely ionized gas. According to the method of formation, two types of plasma are distinguished: thermal, occurring gas to high temperatures, and gaseous, resulting in electrical discharges in the gas environment.

Plasmochemical processes occupied a durable place in a number of industries. They are used for cutting and welding of refractory metals, the synthesis of different substances, the plasma light sources are widely used, promising the application of plasma in thermonuclear power plants, etc.

Introduction

1.Agregate state of the substance - gas

2.Gregate state of the substance - liquid

3.Agregate state of the substance - solid

4. Accounting condition of the substance - plasma

Conclusion

List of used literature

Introduction

As is known, many substances in nature can be in three states: solid, liquid and gaseous.

The interaction of the substance particles in the hard state is the interaction of particles of matter. The distance between molecules is approximately equal to their own sizes. This leads to a sufficiently strong interaction that practically deprives particles of the ability to move: they fluctuate about some equilibrium position. They retain the form and volume.

The properties of liquids are also explained by their structure. Particles of substance in liquids interact less intensively than in solids, and therefore they can jump their location - liquids do not retain their shape - they are fluid.

Gas is a collection of molecules, randomly moving in all directions independently of each other. Gases do not have their own form, occupy the entire volume provided to them and easily compress.

There is another state of substance - plasma.

The purpose of this work is to consider the existing aggregate states of the substance, to identify all their advantages and disadvantages.

To do this, it is necessary to accomplish and consider the following aggregate veins:

2. Fluids

3. Solids

3. The aggregate state of the substance is a solid

Solid, One of the four aggregate states that differ from other aggregative states (liquids, gases, plasma) Stability of the shape and character of the thermal motion of atoms that make small oscillations near the equilibrium provisions. Along with the crystalline state of T. t. There is an amorphous state, including a glassy state. Crystals are characterized by a distant order in the location of atoms. There is no far order in amorphous bodies.

All matter can exist in one of four species. Each of them is a certain aggregate state of the substance. In the nature of the land, only one is represented immediately in three of them. This is water. It is easy to see and evaporated, and melted, and hard. That is, steam, water and ice. Scientists have learned to change the aggregate states of the substance. The greatest complexity for them is only plasma. For this state, special conditions are needed.

What is it, what is it depends on and how is it characterized?

If the body has passed into another aggregate state of the substance, this does not mean that something else appeared. The substance remains the same. If the fluid had water molecules, then they will be the same in a couple with ice. Only their location, speed of movement and strength of interaction with each other will change.

When studying the topic "The aggregate states (grade 8)" are considered only three of them. This is liquid, gas and solid. Their manifestations depend on the physical environmental conditions. The characteristics of these states are presented in the table.

Name of aggregate state	solid	liquid	gas
His properties	saves the form with the volume	has a constant volume, takes the shape of the vessel	does not have permanent volume and forms
Molecules	in the nodes of the crystal lattice	meful	chaotic
Distance between them	comparable with dimensions of molecules	approximately equal to the size of molecules	significantly more than their size
How molecules move	hesitate near the lattice node	do not move from the place of equilibrium, but sometimes they make big jumps	rare collision
How they interact	greatly attract	greatly attract each other	do not attract, repulsive forces manifest themselves when hitting

First condition: solid body

Its fundamental difference from others is that molecules have a strictly defined place. When they talk about a solid aggregate state, then most often they mean crystals. In them, the lattice structure is symmetric and strictly periodical. Therefore, it always remains how the body would not be spread. The oscillatory movement of the molecules of the substance is not enough to destroy this lattice.

But there are also amorphous bodies. They do not have a strict structure in the location of atoms. They can be anywhere. But this place is as stable as in the crystal body. The difference between amorphous substances from crystal in the fact that they do not have a certain melting point (hardening) and they are inherent in fluidity. Bright examples of such substances: glass and plastic.

Second condition: liquid

This aggregate state of the substance is a cross between solid and gas. Therefore, combines some properties from the first and second. So, the distance between the particles and their interaction is similar to what was in the case of crystals. But here is the location and movement closer to gas. Therefore, the form of fluid does not preserve, but spreads along the vessel in which is nanite.

Third condition: gas

For science entitled "Physics" an aggregate state in the form of gas is not in the last place. After all, she studies the surrounding world, and the air is very common in it.

The features of this state consist in the fact that the interaction forces between molecules is practically absent. This explains their free movement. Because of which the gaseous substance fills the entire volume provided to him. Moreover, you can only translate into this state, you only need to increase the temperature for the desired value.

Fourth Condition: Plasma

This aggregate state of the substance is a gas that is fully or partially ionized. This means that in it the number of negative and positively charged particles is almost the same. There is such a situation when the gas is heated. Then there is a sharp acceleration of the process of thermal ionization. It lies in the fact that molecules are divided into atoms. The latter then turn into ions.

Within the framework of the Universe, this state is very common. Because it has all the stars and environments between them. In the boundaries of the earth's surface, it occurs extremely rarely. If you do not count the ionosphere and solar wind, the plasma is possible only during a thunderstorm. In flashes of lightning, such conditions are created in which the atmospheric gases go to the fourth state of the substance.

But this does not mean that the plasma was not created in the laboratory. The first thing that managed to reproduce is a gas discharge. Now the plasma fills the lamps of daylight and neon advertising.

How is the transition between states?

To do this, create certain conditions: constant pressure and a specific temperature. In this case, the change in the aggregate states of the substance is accompanied by the release or absorption of energy. Moreover, this transition does not occur lightly, and requires certain time costs. During all this time, conditions must be unchanged. The transition occurs at the same time the existence of a substance in two hypostasis, which support thermal equilibrium.

The first three states of the substance can interpret one to another. There are direct processes and inverse. They have such names:

• melting (from solid in liquid) and crystallization, for example, melting ice and hardened water;
• vaporization (from liquid in gaseous) and condensation, example is the evaporation of water and obtaining it from steam;
• sublimation (from solid in gaseous) and desublimationFor example, evaporation of dry flavoring for the first of them and frost patterns on the glass to the second.

Melting and crystallization physics

If the solid is heated, then at a certain temperature, called melting temperature A specific substance will begin changing the aggregate state, which is called melting. This process comes with an absorption of energy called amount of warmth And denotes the letter Q.. To calculate it, you will need to know specific warmth of meltingwhich is denoted λ . And the formula takes such an expression:

Q \u003d λ * mwhere m is a mass of a substance that is involved in melting.

If a reverse process occurs, i.e. liquid crystallization, then the conditions are repeated. The only difference is that the energy is allocated, and the "minus" sign appears in the formula.

Various and condensation physics

With the continuation of the heating of the substance, it will gradually approach the temperature at which its intensive evaporation will begin. This process is called vaporization. It is again characterized by the absorption of energy. Only for its calculation you want to know specific heat of vaporization r.. And the formula will be like this:

Q \u003d R * M.

The reverse process or condensation occurs with the allocation of the same amount of heat. Therefore, the formula again appears minus.