Aggregate states of matter (from the Latin aggrego - I attach, I connect) - these are states of the same substance, the transitions between which correspond to abrupt changes in free energy, entropy, density and other physical parameters of the substance.
Gas (French gaz, derived 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 considered as highly superheated or low-saturated vapors.
- 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 vapor mass, which depends on temperature. Saturated steam can become unsaturated if the volume is increased or the temperature is increased. If the vapor temperature is much higher than the boiling point corresponding to given pressure, the steam is said to be 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.
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 considered 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 pressure and temperature 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 broader concept - the concept of phase.
phase is the totality of all parts of the system that have the same chemical composition and are in the same state. 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 by a significantly higher viscosity and numerical values of 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). The particles of solids oscillate around the average equilibrium positions, called the nodes of the crystal lattice; the structure of these substances is characterized a high degree orderliness (long-range and short-range order) - orderliness in arrangement (coordination order), in orientation (orientation order) of structural particles, or orderliness 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 limited from the side of low temperatures by phase transitions, respectively, to the solid (crystallization), superfluid and liquid-anisotropic state.
Definition
Aggregate states of matter (from the Latin aggrego - attach, connect) - these are the states of the same substance - solid, liquid, gaseous.
During the transition from one state to another, an abrupt change in energy, entropy, density and other characteristics of matter occurs.
Solid and liquid bodies
Definition
Solid bodies are bodies that are distinguished by the constancy of shape and volume.
In them, the intermolecular distances are small and the potential energy of the molecules is comparable to the kinetic one. Solids are divided into two types: crystalline and amorphous. Only crystalline bodies are in a state of thermodynamic equilibrium. Amorphous bodies, in fact, represent metastable states, which in their structure approach non-equilibrium, slowly crystallizing liquids. In an amorphous body, a very slow process of crystallization takes place, the process of a gradual transition of a substance into a crystalline phase. The difference between a crystal and an amorphous solid lies primarily in the anisotropy of its properties. The properties of a crystalline body depend on the direction in space. Various kinds of processes, such as thermal conductivity, electrical conductivity, light, sound, propagate in different directions of a solid body in different ways. Amorphous bodies (glass, resins, plastics) are isotopic, like liquids. The only difference between amorphous bodies and liquids is that the latter are fluid, static shear deformations are impossible in them.
Crystalline bodies have the right molecular structure. The anisotropy of its properties is due to the correct structure of the crystal. The correct arrangement of the atoms of a crystal forms the so-called crystal lattice. In different directions, the arrangement of atoms in the lattice is different, which leads to anisotropy. Atoms (or ions, or whole molecules) in the crystal lattice perform random oscillatory motion around the middle positions, which are considered as nodes of the crystal lattice. The higher the temperature, the greater the energy of oscillations, and hence the average amplitude of oscillations. The size of the crystal depends on the amplitude of the oscillations. An increase in the amplitude of oscillations leads to an increase in the size of the body. This explains the thermal expansion of solids.
Definition
Liquid bodies are bodies that have a certain volume, but do not have elasticity of form.
Liquids are characterized by strong intermolecular interaction and low compressibility. A liquid occupies an intermediate position between a solid and a gas. Liquids, like gases, are isotopic. In addition, the liquid has fluidity. In it, as in gases, there are no tangential stresses (shear stresses) of bodies. Liquids are heavy, i.e. their specific gravity is comparable to the specific gravity of solids. Near the crystallization temperatures, their heat capacities and other thermal characteristics are close to those of solids. In liquids, to a certain extent, the correct arrangement of atoms is observed, but only in small areas. Here the atoms also oscillate near the nodes of a quasi-crystalline cell, but unlike the atoms of a solid body, they jump from one node to another from time to time. As a result, the motion of atoms will be very complex: it is oscillatory, but at the same time the center of vibrations moves in space.
Gas, evaporation, condensation and melting
Definition
A gas is a state of matter in which the distances between molecules are large.
The forces of interaction between molecules at low pressures can be neglected. Gas particles fill the entire volume that is provided to the gas. Gases can be considered as highly superheated or unsaturated vapors. Plasma is a special type of gas - it is partially or completely ionized gas, in which the density of positive and negative charges is almost the same. Plasma is a gas of charged particles that interact with each other using electrical forces at a great distance, but do not have a near and far arrangement of particles.
Substances can change from one state of aggregation to another.
Definition
Evaporation is the process of changing the state of aggregation of a substance, in which molecules fly out from the surface of a liquid or solid, the kinetic energy of which exceeds potential energy interactions of molecules.
Evaporation is a phase transition. During evaporation, part of the liquid or solid passes into vapor. A substance in a gaseous state that is in dynamic equilibrium with a liquid is called saturated vapor. In this case, the change in the internal energy of the body:
\[\triangle \ U=\pm mr\ \left(1\right),\]
where m is body weight, r is the specific heat of vaporization (J / kg).
Definition
Condensation is the reverse process of vaporization.
The calculation of the change in internal energy is carried out according to the formula (1).
Definition
Melting is the process of transition of a substance from a solid to a liquid state, the process of changing the state of aggregation of a substance.
When a substance is heated, its internal energy increases, therefore, the speed of thermal movement of molecules increases. In the event that the melting point of the substance is reached, the crystal lattice of the solid begins to break down. Bonds between particles are destroyed, the energy of interaction between particles increases. The heat transferred to the body goes to increase the internal energy of this body, and part of the energy goes to doing work to change the volume of the body when it melts. For most crystalline bodies, the volume increases when melted, but there are exceptions, for example, ice, cast iron. Amorphous bodies do not have a specific melting point. Melting is a phase transition, which is accompanied by an abrupt change in heat capacity at the melting temperature. The melting point depends on the substance and does not change during the process. In this case, the change in the internal energy of the body:
\[\triangle U=\pm m\lambda \left(2\right),\]
where $\lambda $ is the specific heat of fusion (J/kg).
The reverse process of melting is crystallization. The calculation of the change in internal energy is carried out according to the formula (2).
The change in the internal energy of each body of the system in the case of heating or cooling can be calculated by the formula:
\[\triangle U=mc\triangle T\left(3\right),\]
where c is the specific heat of the substance, J/(kgK), $\triangle T$ is the change in body temperature.
When studying the transitions of substances from one state of aggregation to another, it is impossible to do without the so-called heat balance equation, which says: the total amount of heat that is released in a thermally insulated system is equal to the amount of heat (total) that is absorbed in this system.
In its meaning, the heat balance equation is the law of conservation of energy for heat transfer processes in thermally insulated systems.
Example 1
Assignment: There are water and ice in a heat-insulated vessel at a temperature $t_i= 0^oС$. The masses of water ($m_(v\ ))$ and ice ($m_(i\ ))$ are 0.5 kg and 60 g respectively. Water vapor of mass $m_(p\ )=$10 g is let into the water. at temperature $t_p= 100^oС$. What will be the temperature of the water in the vessel after thermal equilibrium is established? The heat capacity of the vessel is ignored.
Solution: Let's determine what processes take place in the system, what aggregate states of matter we had and what we got.
Water vapor condenses, giving off heat.
This heat is used to melt the ice and, possibly, to heat the water available and obtained from the ice.
Let us first check how much heat is released during the condensation of the available mass of steam:
here, from reference materials, we have $r=2.26 10^6\frac(J)(kg)$ - specific heat of vaporization (also applicable for condensation).
Heat needed to melt ice:
here from reference materials we have $\lambda =3.3\cdot 10^5\frac(J)(kg)$ - specific heat of ice melting.
We get that the steam gives off more heat than required, only to melt the existing ice, therefore, we write the heat balance equation in the form:
Heat is released when steam of mass $m_(p\ )$ condenses and water, which is formed from steam, cools from temperature $T_p$ to the desired T. Heat is absorbed when ice of mass $m_(i\ )$ melts and water of mass $m_v+ is heated m_i$ from temperature $T_i$ to $T.\ $ Denote $T-T_i=\triangle T$, for the difference $T_p-T$ we get:
The heat balance equation will take the form:
\ \ \[\triangle T=\frac(rm_(p\ )+cm_(p\ )100-lm_(i\ ))(c\left(m_v+m_i+m_(p\ )\right))\left (1.6\right)\]
We will carry out calculations, taking into account that the heat capacity of water is tabular $c=4.2\cdot 10^3\frac(J)(kgK)$, $T_p=t_p+273=373K,$ $T_i=t_i+273=273K$:
$\triangle T=\frac(2,26\cdot 10^6\cdot 10^(-2)+4,2\cdot 10^3\cdot 10^(-2)10^2-6\cdot 10^ (-2)\cdot 3,3\cdot 10^5)(4,2\cdot 10^3\cdot 5,7\cdot 10^(-1))\approx 3\left(K\right)$then T=273+3=276 (K)
Answer: The temperature of the water in the vessel after the establishment of thermal equilibrium will be equal to 276 K.
Example 2
Task: The figure shows the section of the isotherm corresponding to the transition of a substance from a crystalline to a liquid state. What corresponds to this section on diagram p,T?
The entire set of states depicted in diagram p,V the horizontal segment of the straight line on the diagram p,T is represented by one point that determines the values of p and T, at which the transition from one state of aggregation to another takes place.
Main general education
Line UMK A. V. Peryshkin. Physics (7-9)
Introduction: state of aggregation of matter
Mysterious the world never ceases to amaze. An ice cube thrown into a glass and left at room temperature, in a matter of minutes it will turn into a liquid, and if you leave this liquid on the windowsill for a longer time, it will completely evaporate. This is the easiest way to observe the transitions of one state of aggregation of a substance into another.State of aggregation - a state of a substance that has certain properties: the ability to maintain shape and volume, to have a long-range or short-range order, and others. When it changes aggregate state of matter there is a change in physical properties, as well as density, entropy and free energy.
How and why do these amazing transformations take place? To understand this, remember that everything around is made up of. Atoms and molecules various substances interact with each other, and it is the connection between them that determines what is the state of matter of matter.
There are four types of aggregates:
gaseous,
It seems that chemistry reveals its secrets to us in these amazing transformations. However, it is not. The transition from one state of aggregation to another, as well as or diffusion, are related to physical phenomena, since in these transformations no changes in the molecules of the substance occur and their chemical composition is preserved.
gaseous state
On molecular level a gas is a randomly moving, colliding with the walls of the vessel and with each other, molecules that practically do not interact with each other. Since the gas molecules are not interconnected, the gas fills the entire volume provided to it, interacting and changing direction only when they hit each other.
Unfortunately, it is impossible to see gas molecules with the naked eye and even with a light microscope. However, the gas can be touched. Of course, if you just try to catch gas molecules flying around in the palm of your hand, then you will not succeed. But surely everyone saw (or did it themselves) how someone inflated the tire of a car or bicycle with air, and from soft and wrinkled it became inflated and elastic. And the apparent "weightlessness" of gases will be refuted by the experiment described on page 39 of the textbook "Chemistry Grade 7" edited by O.S. Gabrielyan.
This is because the closed limited volume of the tire gets a large number of molecules, which become crowded, and they begin to hit each other and the tire walls more often, and as a result, the total effect of millions of molecules on the walls is perceived by us as pressure.
But if the gas occupies the entire volume provided to it, why then does it not fly off into space and spread throughout the universe, filling interstellar space? So, something still retains and limits the gases by the atmosphere of the planet?
Quite right. And this - gravitational force. In order to break away from the planet and fly away, the molecules need to develop a speed that exceeds the "escape speed" or second space velocity, and the vast majority of molecules move much more slowly.
Then the following question arises: why do gas molecules do not fall to the ground, but continue to fly? It turns out that thanks to solar energy, air molecules have a solid supply of kinetic energy, which allows them to move against the forces of gravity.
The collection contains questions and tasks of various directions: settlement, qualitative and graphic; technical, practical and historical character. Tasks are divided into topics in accordance with the structure of the textbook “Physics. Grade 9" by authors A. V. Peryshkin, E. M. Gutnik and allow you to implement the requirements stated by the Federal State Educational Standards for meta-subject, subject and personal learning outcomes.
liquid state
By increasing the pressure and/or decreasing the temperature, gases can be converted into a liquid state. Even at the dawn of the nineteenth century, the English physicist and chemist Michael Faraday succeeded in converting chlorine and carbon dioxide into a liquid state, compressing them at very low temperatures. However, some of the gases did not succumb to scientists at that time, and, as it turned out, it was not a lack of pressure, but an inability to reduce the temperature to the required minimum.
Liquid, unlike gas, occupies a certain volume, but it also takes the form of a filled vessel below the surface. Visually, the liquid can be represented as round beads or cereals in a jar. The molecules of a liquid are in close interaction with each other, but freely move relative to each other.
If a drop of water remains on the surface, after a while it will disappear. But we remember that thanks to the law of conservation of mass-energy, nothing disappears and does not disappear without a trace. The liquid will evaporate, i.e. will change its state of aggregation to gaseous.
Evaporation - is the process of transformation of the state of aggregation of a substance, in which molecules, whose kinetic energy exceeds the potential energy of intermolecular interaction, rise from the surface of a liquid or solid.
Evaporation from the surface of solids is called sublimation or sublimation. Most in a simple way observe sublimation is the use of naphthalene to control moths. If you smell a liquid or a solid, then evaporation is occurring. After all, the nose captures the fragrant molecules of the substance.
Liquids surround a person everywhere. The properties of liquids are also familiar to everyone - this is viscosity, fluidity. When it comes to the shape of a liquid, many people say that a liquid has no definite shape. But this only happens on Earth. Due to the force of gravity, a drop of water is deformed.
However, many have seen astronauts catching water balloons of various sizes in zero gravity. In the absence of gravity, the liquid takes the form of a ball. A provides the liquid with a spherical shape force surface tension. Bubble - great way to get acquainted with the force of surface tension on the Earth.
Another property of a liquid is viscosity. Viscosity depends on pressure, chemical composition and temperature. Most liquids obey Newton's law of viscosity, discovered in the 19th century. However, there are a number of highly viscous liquids that, under certain conditions, begin to behave like solids and do not obey Newton's law of viscosity. Such solutions are called non-Newtonian fluids. The simplest example of a non-Newtonian fluid is a suspension of starch in water. If you act on a non-Newtonian fluid with mechanical forces, the fluid will begin to take on the properties of solids and behave like a solid.
Solid state
If, in a liquid, unlike a gas, the molecules no longer move randomly, but around certain centers, then in the solid state of matter atoms and molecules have a clear structure and look like lined up soldiers on parade. And thanks to the crystal lattice, solids occupy a certain volume and have a constant shape.
Under certain conditions, substances that are in the state of aggregation of a liquid can turn into a solid, and solids, on the contrary, when heated, melt and turn into a liquid.
This is because when heated, the internal energy increases, respectively, the molecules begin to move faster, and when the melting temperature is reached, the crystal lattice begins to break down and the aggregate state of the substance changes. For most crystalline bodies, the volume increases during melting, but there are exceptions, for example, ice, cast iron.
Depending on the type of particles that form crystal lattice solid body, the following structure is distinguished:
molecular
metal.
For some substances change in aggregate states occurs easily, as, for example, with water, for other substances, special conditions(pressure, temperature). But in modern physics scientists distinguish another independent state of matter - plasma.
Plasma - ionized gas with the same density of both positive and negative charges. In wildlife, plasma is found in the sun, or during a lightning flash. The northern lights and even the familiar bonfire, which warms us with its warmth during a foray into nature, also refers to plasma.
Artificially created plasma adds brightness to any city. Neon advertising lights are just low-temperature plasma in glass tubes. Conventional fluorescent lamps are also filled with plasma.
Plasma is divided into low-temperature - with an ionization degree of about 1% and a temperature of up to 100 thousand degrees, and high-temperature - ionization of about 100% and a temperature of 100 million degrees (this is the state in which plasma in stars is).
Low-temperature plasma in fluorescent lamps familiar to us is widely used in everyday life.
High-temperature plasma is used in fusion reactions and scientists do not lose hope of using it as a replacement for atomic energy, but the control in these reactions is very difficult. And an uncontrolled thermonuclear reaction proved to be a weapon of colossal power when, on August 12, 1953, the USSR tested a thermonuclear bomb.
Buy
To check the assimilation of the material, we offer a small test.
1. What does not apply to states of aggregation:
liquid
light +
2. The viscosity of Newtonian fluids is subject to:
Boyle-Mariotte law
the law of Archimedes
Newton's law of viscosity +
3. Why the Earth's atmosphere does not fly away into outer space:
because gas molecules cannot develop the second cosmic velocity
because the gravity of the earth acts on the gas molecules +
both answers are correct
4. What does not apply to amorphous substances:
- sealing wax
-
iron +
5. When cooling, the volume increases at:
-
ice +
: [in 30 volumes] / ch. ed. A. M. Prokhorov; 1969-1978, v. 1).
Introduction
1. Aggregate state of matter - gas
2. Aggregate state of matter - liquid
3. Aggregate state of matter - solid
4. The fourth state of matter is plasma
Conclusion
List of used literature
Introduction
As you know, many substances in nature can be in three states: solid, liquid and gaseous.
The interaction of particles of matter in the solid state is most pronounced. The distance between molecules is approximately equal to their own sizes. This leads to a sufficiently strong interaction, which practically deprives the particles of the opportunity to move: they oscillate around a certain equilibrium position. They retain their shape and volume.
The properties of liquids are also explained by their structure. Particles of matter in liquids interact less intensively than in solids, and therefore they can change their location in leaps and bounds - liquids do not retain their shape - they are fluid.
A gas is a collection of molecules moving randomly in all directions independently of each other. Gases do not have their own shape, they occupy the entire volume provided to them and are easily compressed.
There is another state of matter - plasma.
The purpose of this work is to consider the existing aggregate states of matter, to identify all their advantages and disadvantages.
To do this, it is necessary to perform and consider the following aggregate states:
2. fluids
3. solids
3. Aggregate state of matter - solid
Solid, one of the four states of aggregation of matter, which differs from other states of aggregation (liquids, gases, plasmas) the stability of the form and the nature of the thermal motion of atoms that make small vibrations around the equilibrium positions. Along with the crystalline state of T. t., there is an amorphous state, including the glassy state. Crystals are characterized by long-range order in the arrangement of atoms. There is no long-range order in amorphous bodies.
