Gaseous, liquid and solid states of matter. Gaseous substances gaseous substances gaseous substances

H2O - water, Liquid metal - mercury! The liquid state is usually considered intermediate between a solid and a gas: a gas retains neither volume nor shape, but a solid retains both.

Form liquid bodies may be fully or partially determined by the fact that their surface behaves like an elastic membrane. So, water can collect in drops. But liquid is capable of flowing even under its stationary surface, and this also means non-preservation of shape ( internal parts liquid body).

Liquid molecules do not have a definite position, but at the same time they do not have complete freedom of movement. There is an attraction between them that is strong enough to keep them together. close range.

Substance in liquid state exists in a certain temperature range, below which it turns into a solid state (crystallization or transformation into a solid occurs) amorphous state- glass), higher - into gaseous (evaporation occurs). The boundaries of this interval depend on pressure.

As a rule, a substance in the liquid state has only one modification. (The most important exceptions are quantum liquids and liquid crystals.) Therefore, in most cases, liquid is not only an aggregate state, but also a thermodynamic phase ( liquid phase) .

All liquids are usually divided into pure liquids and mixtures. Some liquid mixtures have great importance for life: blood, sea water etc. Liquids can act as solvents.
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Physical properties of liquids
Fluidity

The main property of liquids is fluidity. If you apply to a section of liquid that is in equilibrium external force, then a flow of liquid particles arises in the direction in which this force is applied: the liquid flows. Thus, under the influence of unbalanced external forces, the liquid does not retain its shape and relative arrangement of parts, and therefore takes the shape of the vessel in which it is located.

Unlike plastic solids, a liquid does not have a yield limit: it is enough to apply an arbitrarily small external force for the liquid to flow.
Volume conservation

One of characteristic properties liquid is what it has certain volume(at constant external conditions) . Liquids are extremely difficult to compress mechanically because, unlike gases, there is very little free space between the molecules. The pressure exerted on a liquid enclosed in a vessel is transmitted without change to each point in the volume of this liquid (Pascal’s law is also valid for gases). This feature, along with very low compressibility, is used in hydraulic machines.

Liquids generally increase in volume (expand) when heated and decrease in volume (contract) when cooled. However, there are exceptions, for example, water contracts when heated, at normal pressure and at temperatures from 0 °C to approximately 4 °C.
Viscosity

In addition, liquids (like gases) are characterized by viscosity. It is defined as the ability to resist the movement of one part relative to another - that is, as internal friction.

When adjacent layers of liquid move relative to each other, collisions of molecules inevitably occur in addition to that caused by thermal motion. Forces arise that inhibit orderly movement. Wherein kinetic energy ordered movement turns into thermal energy - the energy of chaotic movement of molecules.

The liquid in the vessel, set in motion and left to its own devices, will gradually stop, but its temperature will increase.

Water and gas. They all differ in their properties. Special place Liquids are on this list. Unlike solids, liquids do not have molecules arranged in an orderly manner. Liquid is special condition a substance intermediate between a gas and a solid. Substances in this form can only exist if certain temperature ranges are strictly observed. Below this interval, the liquid body will turn into a solid, and above - into a gaseous one. In this case, the boundaries of the interval directly depend on pressure.

Water

One of the main examples of a liquid body is water. Despite belonging to this category, water can take the form of a solid or gas - depending on the temperature environment. During the transition from a liquid to a solid state, the molecules of an ordinary substance are compressed. But water behaves completely differently. When it freezes, its density decreases, and instead of sinking, the ice floats to the surface. Water in its ordinary, fluid state has all the properties of a liquid - it always has a specific volume, however, there is no specific shape.

Therefore, water always retains heat under the surface of ice. Even if the ambient temperature is -50°C, under the ice it will still be around zero. However, in elementary school you don’t have to delve into the details of the properties of water or other substances. In grade 3, the simplest examples of liquid bodies can be given - and it is advisable to include water in this list. After all, the student primary school must have general ideas about the properties of the surrounding world. At this stage it is enough to know that water in its normal state is a liquid.

Surface tension is a property of water

Water has a higher surface tension than other liquids. Thanks to this property, raindrops are formed, and, consequently, the water cycle in nature is maintained. Otherwise, water vapor could not so easily turn into drops and spill onto the surface of the earth in the form of rain. Water, indeed, is an example of a liquid body, on which the possibility of the existence of living organisms on our planet directly depends.

Surface tension is caused by the molecules of a liquid being attracted to each other. Each particle tends to surround itself with others and leave the surface of the liquid body. That is why soap bubbles and bubbles formed during boiling water tend to accept liquid form- with this volume, only a sphere can have a minimum surface thickness.

Liquid metals

However, not only the substances familiar to humans, with which he deals in everyday life, belong to the class of liquid bodies. Among this category there are many various elements periodic table Mendeleev. An example of a liquid body is also mercury. This substance is widely used in the manufacture of electrical devices, metallurgy, chemical industry.

Mercury is a liquid, shiny metal that evaporates at room temperature. It is capable of dissolving silver, gold and zinc, thereby forming amalgams. Mercury is an example of what kinds of liquid bodies are classified as dangerous to human life. Its vapors are toxic and hazardous to health. Lethal effect Mercury poisoning usually appears some time after contact.

A metal called cesium is also a liquid. Already at room temperature it is in semi-liquid form. Cesium appears to be a golden-white substance. This metal is slightly similar in color to gold, however, it is lighter.

Sulfuric acid

An example of what kind of liquid bodies there are are also almost all inorganic acids. Eg, sulfuric acid, which appears to be a heavy oily liquid. It has neither color nor smell. When heated, it becomes a very strong oxidizing agent. In the cold, it does not interact with metals - for example, iron and aluminum. This substance exhibits its characteristics only in its pure form. Dilute sulfuric acid does not exhibit oxidizing properties.

Properties

What liquid bodies exist besides those listed? This is blood, oil, milk, mineral oil, alcohol. Their properties allow these substances to easily take the form of containers. Like other liquids, these substances do not lose their volume if they are poured from one vessel to another. What other properties are inherent in each of the substances in this state? Liquid bodies and their properties are well studied by physicists. Let's look at their main characteristics.

Fluidity

One of main characteristics of any body in this category is fluidity. This term refers to the body's ability to accept different shape, even if it is subject to relatively weak external influence. It is thanks to this property that each liquid can flow in streams, splash onto the surrounding surface in drops. If bodies of this category did not have fluidity, it would be impossible to pour water from a bottle into a glass.

Wherein this property expressed in different substances to varying degrees. For example, honey changes shape very slowly compared to water. This characteristic is called viscosity. This property depends on internal structure liquid body. For example, honey molecules are more like tree branches, while water molecules are more like balls with small bulges. When the liquid moves, honey particles seem to “cling to each other” - it is this process that gives it greater viscosity than other types of liquids.

Saving the form

We must also remember that no matter what example of liquid bodies we are talking about, they only change their shape, but do not change their volume. If you pour water into a beaker and pour it into another container, this characteristic will not change, although the body itself will take the form of the new vessel into which it was just poured. The property of volume conservation is explained by the fact that both mutually attractive and repulsive forces act between molecules. It should be noted that liquids are almost impossible to compress using external influence due to the fact that they always take the shape of a container.

Liquid and solids differ in that the latter do not obey. Let us recall that this rule describes the behavior of all liquids and gases, and consists in their property of transmitting the pressure exerted on them in all directions. However, it should be noted that those liquids that have lower viscosity do this faster than more viscous liquid bodies. For example, if you put pressure on water or alcohol, it will spread quite quickly.

Unlike these substances, pressure on honey or liquid oil will spread more slowly, however, just as evenly. In grade 3, examples of liquid bodies can be given without indicating their properties. Students will need more detailed knowledge in high school. However, if the student prepares additional material, this may help to obtain more highly appreciated at the lesson.

Class 2 dangerous goods include pure gases, mixtures of gases, mixtures of one or more gases with one or more other substances, as well as products containing such substances. Substances and products of class 2 are divided into compressed gas; liquefied gas; refrigerated liquefied gas; dissolved gas; aerosol sprays and small containers containing gas (gas cartridges); other products containing gas under pressure; non-pressurized gases covered by special requirements(gas samples). Transporting Class 2 dangerous goods involves the risk of explosion, fire, suffocation, frostbite or poisoning.

Air- a natural mixture of gases consisting by volume of 78% nitrogen, 21% oxygen, 0.93% argon, 0.3% carbon dioxide and very small quantity noble gases, hydrogen, ozone, carbon monoxide, ammonia, methane, sulfur dioxide and others. Density of liquid air 0.96 g/cubic. cm (at -192°C and normal pressure). Air is necessary for many processes to occur: combustion of fuel, smelting of metals from ores, industrial production various chemical compounds. Air is also used to produce oxygen, nitrogen and noble gases; as a refrigerant, heat and sound insulating material, working fluid in electrical insulating devices, pneumatic tires, jet and spray devices, pneumatic machines, etc.

Oxygen - chemical element, with pronounced oxidizing properties. Oxygen is mainly used in medicine. In addition to medicine, oxygen is used in metallurgy and other industries, and liquid oxygen serves as an oxidizer for rocket fuel.

Propane– a colorless, flammable, odorless, explosive gas contained in natural and associated petroleum gases, in gases obtained from CO and H2, as well as during oil refining. Propane has a negative effect on the central nervous system; if liquid propane comes into contact with the skin, frostbite can occur.

Nitrogen- colorless gas, tasteless and odorless. Nitrogen is used in many industries: as an inert medium in various chemical and metallurgical processes, for filling free space in mercury thermometers, when pumping flammable liquids, etc. A liquid nitrogen used in various refrigeration units. Nitrogen is used for industrial production ammonia, which is then processed into nitric acid, fertilizers, explosives, etc.

Chlorine - poisonous gas yellow-green color. The main quantities of chlorine are processed at the site of its production into chlorine-containing compounds. Chlorine is also used for bleaching cellulose and fabrics, for sanitary needs and chlorinating water, as well as for chlorinating some ores to extract titanium, niobium, zirconium, etc. Chlorine poisoning is possible in the chemical, pulp and paper, textile, pharmaceutical industries, etc. d. Chlorine irritates the mucous membranes of the eyes and respiratory tract, often to primary inflammatory changes secondary infection occurs. The concentration of chlorine in the air is 500 mg/m3. m. with fifteen minutes of exposure is fatal. In order to prevent poisoning, it is necessary: sealing production equipment, effective ventilation, use a gas mask if necessary.

Ammonia- colorless gas with a sharp characteristic odor. Ammonia is used to produce nitrogen fertilizers, explosives and polymers, nitric acid, soda and other chemical industry products. Liquid ammonia is used as a solvent. In refrigeration technology, ammonia is used as a refrigerant (717). Also widely used is a 10% ammonia solution ( ammonia) received in medicine. According to its physiological effect on the body, it belongs to the group of substances with asphyxiating and neurotropic effects, capable of causing toxic pulmonary edema and severe damage if inhaled. nervous system. Ammonia has both local and resorptive effects. Ammonia vapors strongly irritate the mucous membranes of the eyes and respiratory organs, as well as the skin, causing excessive lacrimation, eye pain, chemical burns of the conjunctiva and cornea, loss of vision, coughing attacks, redness and itching of the skin. When liquefied ammonia and its solutions come into contact with the skin, a burning sensation occurs, and a chemical burn with blisters and ulcerations is possible. In addition, liquefied ammonia absorbs heat when it evaporates, and when it comes into contact with the skin, frostbite of varying degrees occurs.

The attraction and repulsion of particles determines them mutual arrangement in matter. And the properties of substances significantly depend on the arrangement of particles. So, looking at a transparent, very hard diamond (diamond) and soft black graphite (pencil leads are made from it), we do not realize that both substances consist of exactly the same carbon atoms. It's just that these atoms are arranged differently in graphite than in diamond.

The interaction of particles of a substance leads to the fact that it can be in three states: hard, liquid And gaseous. For example, ice, water, steam. Any substance can be in three states, but this requires certain conditions: pressure, temperature. For example, oxygen in air is a gas, but when cooled below -193 °C it turns into a liquid, and at -219 °C oxygen is a solid. Iron at normal pressure and room temperature is in a solid state. At temperatures above 1539 °C, iron becomes liquid, and at temperatures above 3050 °C it becomes gaseous. Liquid mercury, used in medical thermometers, becomes solid when cooled below -39 °C. At temperatures above 357 °C, mercury turns into vapor (gas).

By turning metallic silver into a gas, it is sprayed onto glass to create “mirror” glasses.

What properties do substances have? various states?

Let's start with gases, in which the behavior of molecules resembles the movement of bees in a swarm. However, bees in a swarm independently change the direction of movement and practically do not collide with each other. At the same time, for molecules in a gas such collisions are not only inevitable, but occur almost continuously. As a result of collisions, the directions and speeds of the molecules change.

The result of such movement and the lack of interaction between particles during movement is that gas retains neither volume nor shape, but occupies the entire volume provided to it. Each of you will consider the statements sheer absurdity: “Air occupies half the volume of the room” and “I pumped air into two-thirds of the volume of a rubber ball.” Air, like any gas, occupies the entire volume of the room and the entire volume of the ball.

What properties do liquids have? Let's conduct an experiment.

Pour water from one beaker into a beaker of another shape. The shape of the liquid has changed, But volume remained the same. The molecules did not scatter throughout the entire volume, as would be the case with a gas. Means, mutual attraction liquid molecules exist, but it does not rigidly hold neighboring molecules. They vibrate and jump from one place to another, which explains the fluidity of liquids.

The strongest interaction is between particles in a solid. It does not allow the particles to disperse. Particles only perform chaotic oscillatory movements around certain positions. That's why solids retain both volume and shape. A rubber ball will retain its ball shape and volume no matter where it is placed: in a jar, on a table, etc.

Lesson type: combined

Target

— formation of a holistic picture of the world and awareness of a person’s place in it based on the unity of rational-scientific knowledge and the child’s emotional and value understanding personal experience communication with people and nature;

Problem:

What is a body, substance, particle?

Tasks:

Distinguish between bodies, substances and particles,

Conduct experiments using laboratory equipment

Subject results

will learn

Characterize the concepts of “body”, “substance”, “particle”;

Distinguish between bodies and substances and classify them.

Universal learning activities(UUD)

Regulatory: adequately use speech to plan and regulate one’s activities; transform practical problem into cognitive.

Cognitive: pose and formulate problems, monitor and evaluate the process and result of activities (experience); transfer of information.

Communicative: cost monologue, argue your position.

Personal results

Motivation for learning activities

Basic concepts and definitions

Bodies, substances, particles. Natural and artificial bodies. Solid, liquid, gaseous substances

Checking readiness to learn new material

Remember into what groups all the objects that surround us can be divided.

Look at the diagram. What two groups can bodies be divided into? Give examples of bodies from each group.

Learning new material

Any item, any Living being can be called a body. A stone, a lump of sugar, a tree, a bird, a wire - these are bodies. It is impossible to list all the bodies; there are countless of them. The sun, planets, and the moon are also bodies. They are called celestial bodies

SUBSTANCES

Bodies are made up of substances. A piece of sugar is a body, and sugar itself is a substance. Aluminum wire is the body, aluminum is the substance.

There are bodies that are formed not by one, but by several or many substances. Very complex composition have living bodies. For example, plants contain water, sugar, starch and other substances. The bodies of animals and humans are formed by many different substances.

So, substances are what bodies are made of.

Distinguish solid, liquid And gaseous substances. Sugar and aluminum are examples of solids. Water - liquid substance. Air consists of several gaseous substances (gases).

BodiesAndsubstances

Bodies. Substances

Experience. Fromwhatconsistsubstances

Threestatesubstances

PARTICLES

Experience. Let's take a body formed by one substance - a piece of sugar. Place it in a glass of water and stir. At first the sugar is clearly visible, but gradually becomes invisible. Let's taste the liquid. She's sweet. This means that the sugar did not disappear, it remained in the glass. Why don't we see him? Make a guess.

A piece of sugar has broken down into tiny pieces visible to the eye the particles of which it consisted (dissolved), and these particles mixed with particles of water.

Conclusion: experience proves that substances, and therefore bodies, consist of particles.

Every substance consists of special particles, which differ in size and shape from particles of other substances.

Scientists have found that there are gaps between particles. In solids these gaps are very small, in liquids they are larger, in gases they are even larger. In any substance, all particles are constantly moving.