What is a state of aggregation? Aggregate state of matter. Alcohols () Ideas about the microworld: from Ancient Greece to the 17th century

"Alcohols" From history  Do you know that back in the IV century. BC e. did people know how to make drinks containing ethyl alcohol? Wine was obtained by fermentation of fruit and berry juices. However, they learned how to extract the intoxicating component from it much later. In the XI century. alchemists caught vapors of a volatile substance that was released when wine was heated. Definition n General formula of monohydric saturated alcohols СnН2n+1ОН Classification of alcohols According to the number of hydroxyl groups CxHy(OH)n Monohydric alcohols CH3 - CH2 - CH2 OH Dihydric glycols CH3 - CH - CH2 OH OH By the nature of the hydrocarbon hydrocarbon radical of the radical CxHy(OH)n CxHy(OH)n Limit Limit CH3 CH3 –– CH CH2 CH2 2 ––CH 2 OH OH Unsaturated Unsaturated CH CH2 = CH CH––CH CH2 2 = 2 OH OH Aromatic Aromatic CH CH2 OH 2 --OH hydrogen corresponding to alcohol, add the (generic) suffix - OL. The numbers after the suffix indicate the position of the hydroxyl group in the main chain: H | H-C-OH | H methanol H H H |3 |2 |1 H- C – C – C -OH | | | H H H propanol-1 H H H | 1 | 2 |3 H - C - C - C -H | | | H OH H propanol -2 TYPES OF ISOMERISM 1. Isomerism of the position of the functional group (propanol–1 and propanol–2) 2. Isomerism of the carbon skeleton CH3-CH2-CH2-CH2-OH butanol-1 CH3-CH-CH2-OH | CH3 2-methylpropanol-1 3. Interclass isomerism - alcohols are isomeric to ethers: CH3-CH2-OH ethanol CH3-O-CH3 dimethyl ether suffix -ol  For polyhydric alcohols, before the suffix -ol in Greek (-di-, -tri-, ...) the number of hydroxyl groups is indicated  For example: CH3-CH2-OH ethanol Types of isomerism of alcohols Structural 1. Carbon chain 2. Functional group positions PHYSICAL PROPERTIES  Lower alcohols (C1-C11) volatile liquids with a pungent odor  Higher alcohols (C12- and higher) solids with a pleasant odor PHYSICAL PROPERTIES Name Formula Pl. g/cm3 tmeltC tbpC Methyl CH3OH 0.792 -97 64 Ethyl C2H5OH 0.790 -114 78 Propyl CH3CH2CH2OH 0.804 -120 92 Isopropyl CH3-CH(OH)-CH3 0.786 -88 82 Butyl CH3CH2CH2CH2OH 0.8108 - Feature 0.8108 -9 physical properties: state of aggregation Methyl alcohol (the first representative of the homologous series of alcohols) is a liquid. Maybe it has a high molecular weight? No. Much less than carbon dioxide. Then what is it? R - O ... H - O ... H - O H R R Why? CH3 - O ... H - O ... N - O H N CH3 And if the radical is large? CH3 - CH2 - CH2 - CH2 - CH2 - O ... H - O H N Hydrogen bonds are too weak to hold an alcohol molecule, which has a large insoluble part, between water molecules A feature of physical properties: contraction Why, when solving calculation problems, they never use volume, but only by weight? Mix 500 ml of alcohol and 500 ml of water. We get 930 ml of solution. The hydrogen bonds between the molecules of alcohol and water are so great that the total volume of the solution decreases, its “compression” (from the Latin contraktio - compression). Individual representatives of alcohols Monohydric alcohol - methanol  Colorless liquid with a boiling point of 64C, characteristic odor Lighter than water. Burns with a colorless flame.  It is used as a solvent and fuel in internal combustion engines Methanol is a poison  The toxic effect of methanol is based on damage to the nervous and vascular systems. Ingestion of 5-10 ml of methanol leads to severe poisoning, and 30 ml or more - to death Monohydric alcohol - ethanol Colorless liquid with a characteristic odor and burning taste, boiling point 78C. Lighter than water. Mixes with her in any relationship. Flammable, burns with a faintly luminous bluish flame. Friendship with the traffic police Are spirits friends with the traffic police? But how! Have you ever been stopped by a traffic police inspector? Did you breathe into a tube? If you were unlucky, then the alcohol oxidation reaction took place, in which the color changed, and you had to pay a fine The question is interesting. Alcohol belongs to xenobiotics - substances that are not contained in the human body, but affect its vital activity. Everything depends on the dose. 1. Alcohol is a nutrient that provides the body with energy. In the Middle Ages, the body received about 25% of its energy from alcohol consumption; 2. Alcohol is a drug that has a disinfectant and antibacterial effect; 3. Alcohol is a poison that disrupts natural biological processes, destroys internal organs and the psyche, and, if consumed excessively, leads to death Use of ethanol  Ethyl alcohol is used in the preparation of various alcoholic beverages;  In medicine for the preparation of extracts from medicinal plants, as well as for disinfection;  In cosmetics and perfumery, ethanol is a solvent for perfumes and lotions Harmful effects of ethanol  At the beginning of intoxication, the structures of the cerebral cortex suffer; the activity of the brain centers that control behavior is suppressed: reasonable control over actions is lost, and a critical attitude towards oneself decreases. I. P. Pavlov called such a state “violence of the subcortex”  With a very high content of alcohol in the blood, the activity of the motor centers of the brain is inhibited, mainly the function of the cerebellum suffers - a person completely loses orientation Harmful effects of ethanol  Changes in the brain structure caused by many years of alcohol intoxication are irreversible, and even after prolonged abstinence from drinking alcohol, they persist. If a person cannot stop, then organic and, consequently, mental deviations from the norm are on the rise Harmful effects of ethanol  Alcohol has an extremely unfavorable effect on the vessels of the brain. At the beginning of intoxication, they expand, the blood flow in them slows down, which leads to congestion in the brain. Then, when, in addition to alcohol, harmful products of its incomplete decay begin to accumulate in the blood, a sharp spasm sets in, vasoconstriction occurs, and such dangerous complications as cerebral strokes develop, leading to severe disability and even death. QUESTIONS FOR CONSOLIDATION 1. 2. 3. 4. 5. 6. 7. 8. There is water in one unsigned vessel, and alcohol in the other. Is it possible to use an indicator to recognize them? Who has the honor of obtaining pure alcohol? Can alcohol be a solid? The molecular weight of methanol is 32, and carbon dioxide is 44. Make a conclusion about the state of aggregation of alcohol. Mixed a liter of alcohol and a liter of water. Determine the volume of the mixture. How to conduct a traffic police inspector? Can anhydrous absolute alcohol release water? What are xenobiotics and how do they relate to alcohols? ANSWERS 1. 2. 3. 4. 5. 6. 7. 8. You can't. Indicators do not affect alcohols and their aqueous solutions. Of course, the alchemists. Maybe if this alcohol contains 12 carbon atoms or more. From these data, no conclusion can be drawn. Hydrogen bonds between alcohol molecules at a low molecular weight of these molecules make the boiling point of alcohol abnormally high. The volume of the mixture will not be two liters, but much less, approximately 1 liter - 860 ml. Don't drink while driving. Maybe if you heat it up and add conc. sulfuric acid. Do not be lazy and remember everything that you have heard about alcohols, decide for yourself once and for all what dose is yours……. and is it needed at all? Polyhydric alcohol ethylene glycol  Ethylene glycol is a representative of limiting dihydric alcohols - glycols;  Glycols got their name due to the sweet taste of many representatives of the series (Greek “glycos” - sweet);  Ethylene glycol is a syrupy liquid of sweet taste, odorless, poisonous. Mixes well with water and alcohol, hygroscopic Use of ethylene glycol  An important property of ethylene glycol is the ability to lower the freezing point of water, from which the substance has found wide application as a component of automotive antifreeze and antifreeze liquids;  It is used to obtain lavsan (a valuable synthetic fiber) Ethylene glycol is a poison  Doses that cause fatal ethylene glycol poisoning vary widely - from 100 to 600 ml. According to some authors, the lethal dose for humans is 50-150 ml. Mortality due to ethylene glycol is very high and accounts for more than 60% of all cases of poisoning;  The mechanism of the toxic action of ethylene glycol has not been sufficiently studied so far. Ethylene glycol is rapidly absorbed (including through the pores of the skin) and circulates in the blood unchanged for several hours, reaching a maximum concentration after 2-5 hours. Then its content in the blood gradually decreases, and it is fixed in the tissues. Colorless, viscous, hygroscopic, sweet-tasting liquid. Miscible with water in all proportions, good solvent. Reacts with nitric acid to form nitroglycerin. Forms fats and oils with carboxylic acids CH2 – CH – CH2 OH OH OH Application of glycerin  Used in     production of nitroglycerine explosives; When processing the skin; As a component of some adhesives; In the production of plastics, glycerin is used as a plasticizer; In the production of confectionery and beverages (as food additive E422) Qualitative reaction to polyhydric alcohols Qualitative reaction to polyhydric alcohols  The reaction to polyhydric alcohols is their interaction with a fresh precipitate of copper (II) hydroxide, which dissolves to form a bright blue-violet solution Tasks Complete work card for the lesson;  Answer the test questions;  Solve the crossword puzzle  Working card of the lesson “Alcohols”  General formula of alcohols  Name the substances:  CH3OH  CH3-CH2-CH2-CH2-OH  CH2(OH)-CH2(OH) the atomicity of the alcohol?  List the uses of ethanol  What alcohols are used in the food industry?  What alcohol causes fatal poisoning when 30 ml is ingested?  What substance is used as antifreeze liquid?  How to distinguish polyhydric alcohol from monohydric alcohol? Production methods Laboratory  Hydrolysis of haloalkanes: R-CL+NaOH R-OH+NaCL  Hydration of alkenes: CH2=CH2+H2O C2H5OH  Hydrogenation of carbonyl compounds Industrial  Synthesis of methanol from synthesis gas CO+2H2 CH3-OH (at elevated pressure, high temperature and zinc oxide catalyst)  Hydration of alkenes  Fermentation of glucose: C6H12O6 2C2H5OH+2CO2 Chemical properties I. Reactions with RO–H bond breaking  Alcohols react with alkali and alkaline earth metals, forming salt-like compounds - alcoholates 2СH CH CH OH + 2Na  2CH CH CH ONa + H  2CH CH OH + Ca  (CH CHO) Ca + H  3 2 3 2 2 3 3 2 2 2 2 2 2  Interaction with organic acids (esterification reaction) leads to the formation of esters. CH COOH + HOC H  CHCOOC H (acetic ethyl ether (ethyl acetate)) + HO 3 2 5 3 2 5 2 II. Reactions with R–OH bond cleavage With hydrogen halides: R–OH + HBr  R–Br + H2O III. Oxidation reactions Alcohols burn: 2C3H7OH + 9O2  6CO2 + 8H2O Under the action of oxidizing agents:  primary alcohols are converted into aldehydes, secondary into ketones IV. Dehydration Occurs when heated with water-removing reagents (conc. H2SO4). 1. Intramolecular dehydration leads to the formation of alkenes CH3–CH2–OH  CH2=CH2 + H2O 2. Intermolecular dehydration gives ethers R-OH + H-O–R  R–O–R(ether) + H2O

Presentation on the topic "Alcohols" in chemistry in powerpoint format. The presentation for schoolchildren contains 12 slides, which, from the point of view of chemistry, talk about alcohols, their physical properties, reactions with hydrogen halides.

Fragments from the presentation

From the history

Do you know that even in the 4th c. BC e. did people know how to make drinks containing ethyl alcohol? Wine was obtained by fermentation of fruit and berry juices. However, they learned how to extract the intoxicating component from it much later. In the XI century. alchemists caught vapors of a volatile substance that was released when wine was heated.

Physical Properties

• Lower alcohols are liquids that are highly soluble in water, colorless, with an odor.
• Higher alcohols are solids, insoluble in water.

Feature of physical properties: state of aggregation

• Methyl alcohol (the first representative of the homologous series of alcohols) is a liquid. Maybe it has a high molecular weight? No. Much less than carbon dioxide. Then what is it?
• It turns out that it's all about the hydrogen bonds that form between alcohol molecules, and do not allow individual molecules to fly away.

Feature of physical properties: solubility in water

• Lower alcohols are soluble in water, higher alcohols are insoluble. Why?
• Hydrogen bonds are too weak to hold an alcohol molecule, which has a large insoluble portion, between water molecules.

Feature of physical properties: contraction

• Why, when solving computational problems, they never use volume, but only mass?
• Mix 500 ml of alcohol and 500 ml of water. We get 930 ml of solution. The hydrogen bonds between the molecules of alcohol and water are so great that the total volume of the solution decreases, its "compression" (from the Latin contraktio - compression).

Are alcohols acids?

• Alcohols react with alkali metals. In this case, the hydrogen atom of the hydroxyl group is replaced by a metal. It looks like acid.
• But the acid properties of alcohols are too weak, so weak that alcohols do not act on indicators.

Friendship with the traffic police.

• Alcohols are friends with the traffic police? But how!
• Have you ever been stopped by a traffic police inspector? Did you breathe into a tube?
• If you were unlucky, then the alcohol oxidation reaction took place, in which the color changed, and you had to pay a fine.

We give water 1

Withdrawal of water - dehydration can be intramolecular if the temperature is more than 140 degrees. In this case, a catalyst is needed - concentrated sulfuric acid.

We give water 2

If the temperature is reduced, and the catalyst is left the same, then intermolecular dehydration will take place.

Reaction with hydrogen halides.

This reaction is reversible and requires a catalyst - concentrated sulfuric acid.

To be friends or not to be friends with alcohol.

The question is interesting. Alcohol belongs to xenobiotics - substances that are not contained in the human body, but affect its vital activity. Everything depends on the dose.

1. Alcohol is a nutrient that provides the body with energy. In the Middle Ages, the body received about 25% of energy through alcohol consumption.
2. Alcohol is a drug that has a disinfectant and antibacterial effect.
3. Alcohol is a poison that disrupts natural biological processes, destroys internal organs and the psyche, and, if consumed in excess, leads to death.

Lecture 4. Aggregate states of matter

1. Solid state of matter.

2. Liquid state of matter.

3. Gaseous state of matter.

Substances can be in three states of aggregation: solid, liquid and gaseous. At very high temperatures, a kind of gaseous state arises - plasma (plasma state).

1. The solid state of matter is characterized by the fact that the energy of interaction between particles is higher than the kinetic energy of their motion. Most substances in the solid state have a crystalline structure. Each substance forms crystals of a certain shape. For example, sodium chloride has crystals in the form of cubes, alum in the form of octahedrons, sodium nitrate in the form of prisms.

The crystalline form of a substance is the most stable. The arrangement of particles in a solid body is depicted as a lattice, at the nodes of which certain particles are connected by imaginary lines. There are four main types of crystal lattices: atomic, molecular, ionic and metallic.

Atomic crystal lattice formed by neutral atoms that are linked by covalent bonds (diamond, graphite, silicon). Molecular crystal lattice have naphthalene, sucrose, glucose. The structural elements of this lattice are polar and non-polar molecules. Ionic crystal lattice It is formed by positively and negatively charged ions (sodium chloride, potassium chloride) regularly alternating in space. All metals have a metallic crystal lattice. At its nodes are positively charged ions, between which there are electrons in a free state.

Crystalline substances have a number of features. One of them is anisotropy - ϶ᴛᴏ dissimilarity of the physical properties of a crystal in different directions inside the crystal.

2. In the liquid state of matter, the energy of intermolecular interaction of particles is commensurate with the kinetic energy of their movement. This state is intermediate between gaseous and crystalline. Unlike gases, large forces of mutual attraction act between liquid molecules, which determines the nature of molecular motion. The thermal motion of a liquid molecule includes vibrational and translational. Each molecule oscillates around a certain equilibrium point for some time, and then moves and again occupies an equilibrium position. This determines its fluidity. The forces of intermolecular attraction do not allow molecules to move far from each other during their movement.

The properties of liquids also depend on the volume of molecules and the shape of their surface. If the liquid molecules are polar, then they are combined (associated) into a complex complex. Such liquids are called associated (water, acetone, alcohol). Οʜᴎ have higher t kip, have lower volatility, higher dielectric constant.

As you know, liquids have surface tension. Surface tension- ϶ᴛᴏ surface energy per unit surface: ϭ = Е/S, where ϭ is surface tension; E is the surface energy; S is the surface area. The stronger the intermolecular bonds in a liquid, the greater its surface tension. Substances that reduce surface tension are called surfactants.

Another property of liquids is viscosity. Viscosity - ϶ᴛᴏ the resistance that occurs when some layers of a liquid move relative to others when it moves. Some liquids have a high viscosity (honey, small), while others are low (water, ethyl alcohol).

3. In the gaseous state of matter, the energy of intermolecular interaction of particles is less than their kinetic energy. For this reason, gas molecules are not held together, but move freely in the volume. Gases are characterized by properties: 1) uniform distribution over the entire volume of the vessel in which they are located; 2) low density compared to liquids and solids; 3) easy compressibility.

In a gas, the molecules are at a very large distance from each other, the forces of attraction between them are small. At large distances between molecules, these forces are practically absent. A gas in this state is called ideal. Real gases at high pressures and low temperatures do not obey the equation of state of an ideal gas (the Mendel-eev-Clapeyron equation), since under these conditions, interaction forces between molecules begin to appear.

Questions about what a state of aggregation is, what features and properties possess solids, liquids and gases are considered in several training courses. There are three classical states of matter, with their own characteristic features of the structure. Their understanding is an important point in comprehending the sciences of the Earth, living organisms, and production activities. These questions are studied by physics, chemistry, geography, geology, physical chemistry and other scientific disciplines. Substances that are under certain conditions in one of the three basic types of state can change with an increase or decrease in temperature or pressure. Let us consider possible transitions from one state of aggregation to another, as they are carried out in nature, technology and everyday life.

What is a state of aggregation?

The word of Latin origin "aggrego" in translation into Russian means "to attach". The scientific term refers to the state of the same body, substance. The existence of solids, gases and liquids at certain temperature values ​​and different pressures is characteristic of all the shells of the Earth. In addition to the three basic aggregate states, there is also a fourth. At elevated temperature and constant pressure, the gas turns into a plasma. To better understand what a state of aggregation is, it is necessary to remember the smallest particles that make up substances and bodies.

The diagram above shows: a - gas; b - liquid; c is a rigid body. In such figures, circles indicate the structural elements of substances. This is a symbol, in fact, atoms, molecules, ions are not solid balls. Atoms consist of a positively charged nucleus around which negatively charged electrons move at high speed. Knowledge of the microscopic structure of matter helps to better understand the differences that exist between different aggregate forms.

Ideas about the microworld: from Ancient Greece to the 17th century

The first information about the particles that make up physical bodies appeared in ancient Greece. Thinkers Democritus and Epicurus introduced such a concept as an atom. They believed that these smallest indivisible particles of different substances have a shape, certain sizes, are capable of movement and interaction with each other. Atomistics became the most advanced teaching of ancient Greece for its time. But its development slowed down in the Middle Ages. Since then scientists were persecuted by the Inquisition of the Roman Catholic Church. Therefore, until modern times, there was no clear concept of what the state of aggregation of matter is. Only after the 17th century did the scientists R. Boyle, M. Lomonosov, D. Dalton, A. Lavoisier formulate the provisions of the atomic-molecular theory, which have not lost their significance even today.

Atoms, molecules, ions - microscopic particles of the structure of matter

A significant breakthrough in understanding the microcosm occurred in the 20th century, when the electron microscope was invented. Taking into account the discoveries made by scientists earlier, it was possible to put together a harmonious picture of the microworld. Theories describing the state and behavior of the smallest particles of matter are quite complex, they belong to the field. To understand the features of different aggregate states of matter, it is enough to know the names and features of the main structural particles that form different substances.

1. Atoms are chemically indivisible particles. Preserved in chemical reactions, but destroyed in nuclear. Metals and many other substances of atomic structure have a solid state of aggregation under normal conditions.
2. Molecules are particles that are broken down and formed in chemical reactions. oxygen, water, carbon dioxide, sulfur. The state of aggregation of oxygen, nitrogen, sulfur dioxide, carbon, oxygen under normal conditions is gaseous.
3. Ions are charged particles that atoms and molecules turn into when they gain or lose electrons - microscopic negatively charged particles. Many salts have an ionic structure, for example, table salt, iron and copper sulfate.

There are substances whose particles are located in space in a certain way. The ordered mutual position of atoms, ions, molecules is called a crystal lattice. Usually ionic and atomic crystal lattices are typical for solids, molecular - for liquids and gases. Diamond has a high hardness. Its atomic crystal lattice is formed by carbon atoms. But soft graphite also consists of atoms of this chemical element. Only they are located differently in space. The usual state of aggregation of sulfur is a solid, but at high temperatures the substance turns into a liquid and an amorphous mass.

Substances in a solid state of aggregation

Solids under normal conditions retain their volume and shape. For example, a grain of sand, a grain of sugar, salt, a piece of rock or metal. If sugar is heated, the substance begins to melt, turning into a viscous brown liquid. Stop heating - again we get a solid. This means that one of the main conditions for the transition of a solid into a liquid is its heating or an increase in the internal energy of the particles of the substance. The solid state of aggregation of salt, which is used in food, can also be changed. But to melt table salt, you need a higher temperature than when heating sugar. The fact is that sugar consists of molecules, and table salt consists of charged ions, which are more strongly attracted to each other. Solids in liquid form do not retain their shape because the crystal lattices break down.

The liquid state of aggregation of the salt during melting is explained by the breaking of the bond between the ions in the crystals. Charged particles are released that can carry electrical charges. Molten salts conduct electricity and are conductors. In the chemical, metallurgical and engineering industries, solids are converted into liquids to obtain new compounds from them or give them different shapes. Metal alloys are widely used. There are several ways to obtain them, associated with changes in the state of aggregation of solid raw materials.

Liquid is one of the basic states of aggregation

If you pour 50 ml of water into a round bottom flask, you will notice that the substance immediately takes the form of a chemical vessel. But as soon as we pour the water out of the flask, the liquid will immediately spread over the surface of the table. The volume of water will remain the same - 50 ml, and its shape will change. These features are characteristic of the liquid form of the existence of matter. Liquids are many organic substances: alcohols, vegetable oils, acids.

Milk is an emulsion, that is, a liquid in which there are droplets of fat. A useful liquid mineral is oil. It is extracted from wells using drilling rigs on land and in the ocean. Sea water is also a raw material for industry. Its difference from the fresh water of rivers and lakes lies in the content of dissolved substances, mainly salts. During evaporation from the surface of water bodies, only H 2 O molecules pass into the vapor state, solutes remain. Methods for obtaining useful substances from sea water and methods for its purification are based on this property.

With complete removal of salts, distilled water is obtained. It boils at 100°C and freezes at 0°C. The brines boil and turn into ice at different temperatures. For example, water in the Arctic Ocean freezes at a surface temperature of 2°C.

The aggregate state of mercury under normal conditions is a liquid. This silver-gray metal is usually filled with medical thermometers. When heated, the column of mercury rises on the scale, the substance expands. Why is alcohol tinted with red paint used, and not mercury? This is explained by the properties of liquid metal. At 30-degree frosts, the state of aggregation of mercury changes, the substance becomes solid.

If the medical thermometer is broken and the mercury has spilled out, then it is dangerous to collect silver balls with your hands. It is harmful to inhale mercury vapor, this substance is very toxic. Children in such cases need to seek help from parents, adults.

gaseous state

Gases cannot retain their volume or shape. Fill the flask to the top with oxygen (its chemical formula is O 2). As soon as we open the flask, the molecules of the substance will begin to mix with the air in the room. This is due to Brownian motion. Even the ancient Greek scientist Democritus believed that the particles of matter are in constant motion. In solids, under normal conditions, atoms, molecules, ions do not have the opportunity to leave the crystal lattice, to free themselves from bonds with other particles. This is possible only when a large amount of energy is supplied from outside.

In liquids, the distance between particles is slightly greater than in solids; they require less energy to break intermolecular bonds. For example, the liquid aggregate state of oxygen is observed only when the gas temperature drops to −183 °C. At -223 ° C, O 2 molecules form a solid. When the temperature rises above the given values, oxygen turns into a gas. It is in this form that it is under normal conditions. At industrial enterprises, there are special installations for separating atmospheric air and obtaining nitrogen and oxygen from it. First, the air is cooled and liquefied, and then the temperature is gradually increased. Nitrogen and oxygen turn into gases under different conditions.

The Earth's atmosphere contains 21% oxygen and 78% nitrogen by volume. In liquid form, these substances are not found in the gaseous envelope of the planet. Liquid oxygen has a light blue color and is filled at high pressure into cylinders for use in medical facilities. In industry and construction, liquefied gases are necessary for many processes. Oxygen is needed for gas welding and cutting of metals, in chemistry - for the oxidation reactions of inorganic and organic substances. If you open the valve of an oxygen cylinder, the pressure decreases, the liquid turns into a gas.

Liquefied propane, methane and butane are widely used in energy, transport, industry and household activities. These substances are obtained from natural gas or during the cracking (splitting) of petroleum feedstock. Carbon liquid and gaseous mixtures play an important role in the economy of many countries. But oil and natural gas reserves are severely depleted. According to scientists, this raw material will last for 100-120 years. An alternative source of energy is air flow (wind). Fast-flowing rivers, tides on the shores of the seas and oceans are used to operate power plants.

Oxygen, like other gases, can be in the fourth state of aggregation, representing a plasma. An unusual transition from a solid to a gaseous state is a characteristic feature of crystalline iodine. A dark purple substance undergoes sublimation - turns into a gas, bypassing the liquid state.

How are transitions from one aggregate form of matter to another carried out?

Changes in the aggregate state of substances are not associated with chemical transformations, these are physical phenomena. When the temperature rises, many solids melt and turn into liquids. A further increase in temperature can lead to evaporation, that is, to the gaseous state of the substance. In nature and economy, such transitions are characteristic of one of the main substances on Earth. Ice, liquid, steam are the states of water under different external conditions. The compound is the same, its formula is H 2 O. At a temperature of 0 ° C and below this value, water crystallizes, that is, it turns into ice. When the temperature rises, the resulting crystals are destroyed - the ice melts, liquid water is again obtained. When it is heated, evaporation is formed - the transformation of water into gas - goes on even at low temperatures. For example, frozen puddles gradually disappear because the water evaporates. Even in frosty weather, wet clothes dry out, but this process is longer than on a hot day.

All the listed transitions of water from one state to another are of great importance for the nature of the Earth. Atmospheric phenomena, climate and weather are associated with the evaporation of water from the surface of the oceans, the transfer of moisture in the form of clouds and fog to land, precipitation (rain, snow, hail). These phenomena form the basis of the World water cycle in nature.

How do the aggregate states of sulfur change?

Under normal conditions, sulfur is bright shiny crystals or a light yellow powder, that is, it is a solid. The aggregate state of sulfur changes when heated. First, when the temperature rises to 190 ° C, the yellow substance melts, turning into a mobile liquid.

If you quickly pour liquid sulfur into cold water, you get a brown amorphous mass. With further heating of the sulfur melt, it becomes more and more viscous and darkens. At temperatures above 300 ° C, the state of aggregation of sulfur changes again, the substance acquires the properties of a liquid, becomes mobile. These transitions arise due to the ability of the atoms of the element to form chains of different lengths.

Why can substances be in different physical states?

The state of aggregation of sulfur - a simple substance - is solid under normal conditions. Sulfur dioxide is a gas, sulfuric acid is an oily liquid heavier than water. Unlike hydrochloric and nitric acids, it is not volatile; molecules do not evaporate from its surface. What state of aggregation has plastic sulfur, which is obtained by heating crystals?

In an amorphous form, the substance has the structure of a liquid, having a slight fluidity. But plastic sulfur simultaneously retains its shape (as a solid). There are liquid crystals that have a number of characteristic properties of solids. Thus, the state of matter under different conditions depends on its nature, temperature, pressure and other external conditions.

What are the features in the structure of solids?

The existing differences between the main aggregate states of matter are explained by the interaction between atoms, ions and molecules. For example, why does the solid aggregate state of matter lead to the ability of bodies to maintain volume and shape? In the crystal lattice of a metal or salt, structural particles are attracted to each other. In metals, positively charged ions interact with the so-called "electron gas" - the accumulation of free electrons in a piece of metal. Salt crystals arise due to the attraction of oppositely charged particles - ions. The distance between the above structural units of solids is much smaller than the size of the particles themselves. In this case, electrostatic attraction acts, it gives strength, and repulsion is not strong enough.

To destroy the solid state of aggregation of a substance, efforts must be made. Metals, salts, atomic crystals melt at very high temperatures. For example, iron becomes liquid at temperatures above 1538 °C. Tungsten is refractory and is used to make incandescent filaments for light bulbs. There are alloys that become liquid at temperatures above 3000 °C. Many on Earth are in a solid state. This raw material is extracted with the help of equipment in mines and quarries.

To detach even one ion from a crystal, it is necessary to expend a large amount of energy. But after all, it is enough to dissolve salt in water for the crystal lattice to disintegrate! This phenomenon is explained by the amazing properties of water as a polar solvent. H 2 O molecules interact with salt ions, destroying the chemical bond between them. Thus, dissolution is not a simple mixing of different substances, but a physical and chemical interaction between them.

How do the molecules of liquids interact?

Water can be liquid, solid and gas (steam). These are its main states of aggregation under normal conditions. Water molecules are made up of one oxygen atom with two hydrogen atoms bonded to it. There is a polarization of the chemical bond in the molecule, a partial negative charge appears on the oxygen atoms. Hydrogen becomes the positive pole in the molecule and is attracted to the oxygen atom of another molecule. This is called the "hydrogen bond".

The liquid state of aggregation is characterized by distances between structural particles comparable to their sizes. The attraction exists, but it is weak, so the water does not retain its shape. Vaporization occurs due to the destruction of bonds, which occurs on the surface of the liquid even at room temperature.

Are there intermolecular interactions in gases?

The gaseous state of a substance differs from liquid and solid in a number of parameters. Between the structural particles of gases there are large gaps, much larger than the size of the molecules. In this case, the forces of attraction do not work at all. The gaseous state of aggregation is characteristic of substances present in the composition of air: nitrogen, oxygen, carbon dioxide. In the figure below, the first cube is filled with a gas, the second with a liquid, and the third with a solid.

Many liquids are volatile; molecules of a substance break off from their surface and pass into the air. For example, if you bring a cotton swab dipped in ammonia to the opening of an open bottle of hydrochloric acid, white smoke appears. Right in the air, a chemical reaction occurs between hydrochloric acid and ammonia, ammonium chloride is obtained. What state of matter is this substance in? Its particles, which form white smoke, are the smallest solid crystals of salt. This experiment must be carried out under an exhaust hood, the substances are toxic.

Conclusion

The aggregate state of gas was studied by many outstanding physicists and chemists: Avogadro, Boyle, Gay-Lussac, Claiperon, Mendeleev, Le Chatelier. Scientists have formulated laws that explain the behavior of gaseous substances in chemical reactions when external conditions change. Open regularities not only entered the school and university textbooks of physics and chemistry. Many chemical industries are based on knowledge about the behavior and properties of substances in different states of aggregation.