How and when do liquids turn into gases? Solutions Effects of ion association in organic chemistry

Mixtures may differ from each other not only in composition, but also by appearance. According to what this mixture looks like and what properties it has, it can be classified as either homogeneous (homogeneous), or to heterogeneous (heterogeneous) mixtures.

Homogeneous (homogeneous) These are mixtures in which particles of other substances cannot be detected even with a microscope.

The composition and physical properties in all parts of such a mixture are the same, since there are no interfaces between its individual components.

TO homogeneous mixtures relate:

• gas mixtures;
• solutions;
• alloys.

Gas mixtures

An example of such a homogeneous mixture is air.

Clean air contains various gaseous substances:

• nitrogen (its volume fraction in clean air is \(78\)%));
• oxygen (\(21\)%));
• noble gases - argon and others (\(0.96\)%));
• carbon dioxide (\(0.04\)%).

The gaseous mixture is natural gas And associated petroleum gas. The main components of these mixtures are gaseous hydrocarbons: methane, ethane, propane and butane.

Also a gaseous mixture is a renewable resource such as biogas, formed when bacteria process organic residues in landfills, in wastewater treatment tanks and in special installations. The main component of biogas is methane, which contains an admixture of carbon dioxide, hydrogen sulfide and a number of other gaseous substances.

Gas mixtures: air and biogas. The air can be sold to curious tourists, and biogas obtained from green mass in special containers can be used as fuel

Solutions

This is usually the name given to liquid mixtures of substances, although this term in science has a broader meaning: a solution is usually called any(including gaseous and solid) homogeneous mixture substances. So, about liquid solutions.

An important solution found in nature is oil. Liquid products obtained during its processing: gasoline, kerosene, diesel fuel, fuel oil, lubricating oils- are also a mixture of different hydrocarbons.

Pay attention!

To prepare a solution, you need to mix a gaseous, liquid or solid substance with a solvent (water, alcohol, acetone, etc.).

For example, ammonia obtained by dissolving ammonia gas in the input. In turn, for cooking iodine tinctures Crystalline iodine is dissolved in ethyl alcohol (ethanol).

Liquid homogeneous mixtures (solutions): oil and ammonia

The alloy (solid solution) can be obtained based on any metal, and its composition may include many different substances.

The most important ones at present are iron alloys- cast iron and steel.

Cast irons are iron alloys containing more than \(2\)% carbon, and steels are iron alloys containing less carbon.

What is commonly called "iron" is actually low carbon steel. Except carbon iron alloys may contain silicon, phosphorus, sulfur.

Exercise 1. Insert these adjectives instead of dots liquid, solid, gaseous .

Exercise 2. Answer the questions.

          1. What substances are found in nature?
         2. What state is the salt in?
         3. What state is bromine in?
         4. What state is nitrogen in?
         5. What state are hydrogen and oxygen in?

Exercise 3. Insert the necessary words instead of dots.

          1. There are... substances in nature.
         2. Bromine is in ... state.
         3. Salt is... a substance.
         4. Nitrogen is in ... state.
         5. Hydrogen and oxygen are... substances.
         6. They are in... condition.

Exercise 4. Listen to the text. Read it out loud.

         Chemical substances are soluble or insoluble in water. For example, sulfur (S) is insoluble in water. Iodine (I 2) is also insoluble in water. Oxygen (O 2) and nitrogen (N 2) are poorly soluble in water. These are substances that are slightly soluble in water. Some chemicals dissolve well in water, such as sugar.

Exercise 5. Answer the questions to the text of Exercise 4. Write down your answers in your notebook.

          1. What substances do not dissolve in water?
         2. What substances dissolve well in water?
         3. What substances do you know that are slightly soluble in water?

Exercise 6. Complete the sentences.

          1. Chemicals dissolve or….
         2. Some chemicals are good...
         3. Glucose and sucrose….
         4. Oxygen and nitrogen are bad...
         5. Sulfur and iodine….

Exercise 7. Write sentences. Use the words in brackets in the correct form.

          1. Salt dissolves in (ordinary water).
         2. Some fats dissolve in (gasoline).
         3. Silver dissolves in (nitric acid).
         4. Many metals dissolve in (sulfuric acid - H 2 SO 4).
         5. Glass does not dissolve even in (hydrochloric acid - HCl).
         6. Oxygen and nitrogen are poorly soluble in (water).
         7. Iodine dissolves well in (alcohol or benzene).

Exercise 8. Listen to the text. Read it out loud.

         All substances have physical properties. Physical properties are color, taste and smell. For example, sugar is white in color and tastes sweet. Chlorine (Cl 2) has a yellow-green color and a strong, unpleasant odor. Sulfur (S) is yellow in color, and bromine (Br 2) is dark red. Graphite (C) is dark gray in color and copper (Cu) is light pink. NaCl salt is white in color and has a salty taste. Some salts have a bitter taste. Bromine has a pungent odor.

Exercise 9. Answer the questions to the text of Exercise 8. Write down the answers in your notebook.

          1. What physical properties do you know?
         2. What physical properties does sugar have?
         3. What physical properties does chlorine have?
         4. What color are graphite, sulfur, bromine and copper?
         5. What physical properties does sodium chloride (NaCl) have?
         6. What do some salts taste like?
         7. What does bromine smell like?

Exercise 10. Make up sentences based on the model.

          Sample: Nitrogen is taste.   Nitrogen has no taste.   Nitrogen has no taste.   Nitrogen is a substance without taste.

         1. Sodium chloride - odor. -...
         2. Chalk – taste and smell. -...
         3. Alcohol is color. -...
         4. Water – taste, color and smell. -...
         5. Sugar is a smell. -...
         6. Graphite – taste and smell. –….

Exercise 11. Say that substances have the same properties as water.

          Sample: Water is a complex substance, ethyl alcohol is also a complex substance.

         1. Water is a liquid, nitric acid too...
         2. Water is a transparent substance, sulfuric acid too...
         3. Water has no color, neither does diamond...
         4. Water has no odor, oxygen too... .

Exercise 12. Say that water has different qualities than ethyl alcohol.

          1. Ethyl alcohol is a light liquid, and water...
         2. Ethyl alcohol has a characteristic odor, and water...
         3. Ethyl alcohol has a low boiling point, and water...

Exercise 13. Clarify the following messages, use words characteristic, specific, sharp, violet, red-brown, colorless, tall, yellow .

          Sample: Bromine is a dark liquid. Bromine is a dark red liquid.

         1. Ethyl alcohol has an odor. 2. Iodine has a smell. 3. Iodine vapors are colored. 4. Dark iodine solution. 5. Sulfuric acid is a liquid. 6. Sulfuric acid has a boiling point. 7. Sulfur has color.

Exercise 14. Talk about the physical properties of substances, use the given words and phrases.

          1. Fluorine (F 2) – gas – light green color – pungent odor – poisonous.
         2. Chlorine (Cl 2) – gas – yellow-green color – pungent odor – poisonous.

I remember how the definition of the state of aggregation of a substance was explained to us back in elementary school. The teacher gave a good example about the tin soldier and then everything became clear to everyone. Below I will try to refresh my memories.

Determine the state of matter

Well, everything is simple here: if you pick up a substance, you can touch it, and when you press on it, it retains its volume and shape - this is a solid state. In a liquid state, a substance does not retain its shape, but retains its volume. For example, there is water in a glass; at the moment it has the shape of a glass. And if you pour it into a cup, it will take the shape of a cup, but the amount of water itself will not change. This means that a substance in a liquid state can change shape, but not volume. In the gaseous state, neither the shape nor the volume of the substance is preserved, but it tries to fill all the available space.

And in relation to the table, it is worth mentioning that sugar and salt may seem like liquid substances, but in fact they are free-flowing substances, their entire volume consists of small solid crystals.

States of matter: liquid, solid, gaseous

All substances in the world are in a certain state: solid, liquid or gas. And any substance can change from one state to another. Surprisingly, even a tin soldier can be liquid. But for this it is necessary to create certain conditions, namely, place it in a very, very heated room, where the tin will melt and turn into liquid metal.

But it’s easiest to consider states of aggregation using water as an example.

• If liquid water is frozen, it turns into ice - this is its solid state.
• If liquid water is heated strongly, it will begin to evaporate - this is its gaseous state.
• And if you heat ice, it will begin to melt and turn back into water - this is called the liquid state.

The process of condensation is especially worth highlighting: if you concentrate and cool evaporated water, the gaseous state will turn into a solid - this is called condensation, and this is how snow is formed in the atmosphere.

Today, the existence of more than 3 million different substances is known. And this figure is growing every year, as synthetic chemists and other scientists are constantly conducting experiments to obtain new compounds that have some useful properties.

Some substances are natural inhabitants, formed naturally. The other half are artificial and synthetic. However, in both the first and second cases, a significant part is made up of gaseous substances, examples and characteristics of which we will consider in this article.

Aggregate states of substances

Since the 17th century, it was generally accepted that all known compounds are capable of existing in three states of aggregation: solid, liquid, and gaseous substances. However, careful research in recent decades in the fields of astronomy, physics, chemistry, space biology and other sciences has proven that there is another form. This is plasma.

What is she? This is partially or completely. And it turns out that there is an overwhelming majority of such substances in the Universe. So, it is in the plasma state that the following are found:

• interstellar matter;
• cosmic matter;
• upper layers of the atmosphere;
• nebulae;
• composition of many planets;
• stars.

Therefore, today they say that there are solids, liquids, gases and plasma. By the way, every gas can be artificially transferred to this state if it is subjected to ionization, that is, forced to turn into ions.

Gaseous substances: examples

There are a lot of examples of the substances under consideration. After all, gases have been known since the 17th century, when van Helmont, a natural scientist, first obtained carbon dioxide and began to study its properties. By the way, he also gave the name to this group of compounds, since, in his opinion, gases are something disordered, chaotic, associated with spirits and something invisible, but tangible. This name has taken root in Russia.

It is possible to classify all gaseous substances, then it will be easier to give examples. After all, it is difficult to cover all the diversity.

According to the composition they are distinguished:

• simple,
• complex molecules.

The first group includes those that consist of identical atoms in any quantity. Example: oxygen - O 2, ozone - O 3, hydrogen - H 2, chlorine - CL 2, fluorine - F 2, nitrogen - N 2 and others.

• hydrogen sulfide - H 2 S;
• hydrogen chloride - HCL;
• methane - CH 4;
• sulfur dioxide - SO 2;
• brown gas - NO 2;
• freon - CF 2 CL 2;
• ammonia - NH 3 and others.

Classification by nature of substances

You can also classify the types of gaseous substances according to their belonging to the organic and inorganic world. That is, by the nature of the atoms that make up it. Organic gases are:

• the first five representatives (methane, ethane, propane, butane, pentane). General formula C n H 2n+2 ;
• ethylene - C 2 H 4;
• acetylene or ethylene - C 2 H 2;
• methylamine - CH 3 NH 2 and others.

Another classification that can be applied to the compounds in question is division based on the particles they contain. Not all gaseous substances are made of atoms. Examples of structures in which ions, molecules, photons, electrons, Brownian particles, and plasma are present also refer to compounds in this state of aggregation.

Properties of gases

The characteristics of substances in the state under consideration differ from those of solid or liquid compounds. The thing is that the properties of gaseous substances are special. Their particles are easily and quickly mobile, the substance as a whole is isotropic, that is, the properties are not determined by the direction of movement of the structures included in the composition.

It is possible to identify the most important physical properties of gaseous substances, which will distinguish them from all other forms of existence of matter.

1. These are connections that cannot be seen, controlled, or felt by ordinary human means. To understand the properties and identify a particular gas, they rely on four parameters that describe them all: pressure, temperature, amount of substance (mol), volume.
2. Unlike liquids, gases are capable of occupying the entire space without a trace, limited only by the size of the vessel or room.
3. All gases easily mix with each other, and these compounds do not have an interface.
4. There are lighter and heavier representatives, so under the influence of gravity and time, it is possible to see their separation.
5. Diffusion is one of the most important properties of these compounds. The ability to penetrate other substances and saturate them from the inside, while performing completely disordered movements within its structure.
6. Real gases cannot conduct electric current, but if we talk about rarefied and ionized substances, then the conductivity increases sharply.
7. The heat capacity and thermal conductivity of gases is low and varies among different species.
8. Viscosity increases with increasing pressure and temperature.
9. There are two options for interphase transition: evaporation - a liquid turns into vapor, sublimation - a solid substance, bypassing the liquid one, becomes gaseous.

A distinctive feature of vapors from true gases is that the former, under certain conditions, are capable of turning into a liquid or solid phase, while the latter are not. It should also be noted that the compounds in question are able to resist deformation and be fluid.

Such properties of gaseous substances allow them to be widely used in various fields of science and technology, industry and the national economy. In addition, specific characteristics are strictly individual for each representative. We considered only the features common to all real structures.

Compressibility

At different temperatures, as well as under the influence of pressure, gases are able to compress, increasing their concentration and reducing their occupied volume. At elevated temperatures they expand, at low temperatures they contract.

Changes also occur under pressure. The density of gaseous substances increases and, upon reaching a critical point, which is different for each representative, a transition to another state of aggregation may occur.

The main scientists who contributed to the development of the study of gases

There are many such people, because the study of gases is a labor-intensive and historically long process. Let us dwell on the most famous personalities who managed to make the most significant discoveries.

1. made a discovery in 1811. It doesn’t matter what kind of gases, the main thing is that under the same conditions, one volume contains an equal amount of them in terms of the number of molecules. There is a calculated value named after the name of the scientist. It is equal to 6.03 * 10 23 molecules for 1 mole of any gas.
2. Fermi - created the theory of an ideal quantum gas.
3. Gay-Lussac, Boyle-Marriott - the names of the scientists who created the basic kinetic equations for calculations.
4. Robert Boyle.
5. John Dalton.
6. Jacques Charles and many other scientists.

Structure of gaseous substances

The most important feature in the construction of the crystal lattice of the substances under consideration is that its nodes contain either atoms or molecules that are connected to each other by weak covalent bonds. Van der Waals forces are also present when it comes to ions, electrons and other quantum systems.

Therefore, the main types of structure of gas lattices are:

• atomic;
• molecular.

The connections inside are easily broken, so these connections do not have a constant shape, but fill the entire spatial volume. This also explains the lack of electrical conductivity and poor thermal conductivity. But gases have good thermal insulation, because, thanks to diffusion, they are able to penetrate into solids and occupy free cluster spaces inside them. At the same time, air is not passed through, heat is retained. This is the basis for the combined use of gases and solids for construction purposes.

Simple substances among gases

We have already discussed above which gases belong to this category in terms of structure and structure. These are those that consist of identical atoms. Many examples can be given, because a significant part of non-metals from the entire periodic table under normal conditions exists in precisely this state of aggregation. For example:

• white phosphorus - one of this element;
• nitrogen;
• oxygen;
• fluorine;
• chlorine;
• helium;
• neon;
• argon;
• krypton;
• xenon.

The molecules of these gases can be either monatomic (noble gases) or polyatomic (ozone - O 3). The type of bond is covalent nonpolar, in most cases it is quite weak, but not in all of them. The crystal lattice is of a molecular type, which allows these substances to easily move from one state of aggregation to another. For example, iodine under normal conditions is dark purple crystals with a metallic luster. However, when heated, they sublimate into clouds of bright purple gas - I 2.

By the way, any substance, including metals, can exist in a gaseous state under certain conditions.

Complex compounds of gaseous nature

Such gases, of course, are the majority. Various combinations of atoms in molecules, united by covalent bonds and van der Waals interactions, allow the formation of hundreds of different representatives of the considered state of aggregation.

Examples of complex substances among gases can be all compounds consisting of two or more different elements. This may include:

• propane;
• butane;
• acetylene;
• ammonia;
• silane;
• phosphine;
• methane;
• carbon disulfide;
• sulphur dioxide;
• brown gas;
• freon;
• ethylene and others.

Crystal lattice of molecular type. Many of the representatives easily dissolve in water, forming the corresponding acids. Most of these compounds are an important part of chemical syntheses carried out in industry.

Methane and its homologues

Sometimes the general concept of “gas” refers to a natural mineral, which is a whole mixture of gaseous products of predominantly organic nature. It contains substances such as:

• methane;
• ethane;
• propane;
• butane;
• ethylene;
• acetylene;
• pentane and some others.

In industry, they are very important, because the propane-butane mixture is the household gas with which people cook, which is used as a source of energy and heat.

Many of them are used for the synthesis of alcohols, aldehydes, acids and other organic substances. Annual consumption of natural gas amounts to trillions of cubic meters, and this is quite justified.

Oxygen and carbon dioxide

What gaseous substances can be called the most widespread and known even to first-graders? The answer is obvious - oxygen and carbon dioxide. After all, they are the direct participants in the gas exchange that occurs in all living beings on the planet.

It is known that it is thanks to oxygen that life is possible, since only some types of anaerobic bacteria can exist without it. And carbon dioxide is a necessary “food” product for all plants that absorb it in order to carry out the process of photosynthesis.

From a chemical point of view, both oxygen and carbon dioxide are important substances for carrying out syntheses of compounds. The first is a strong oxidizing agent, the second is more often a reducing agent.

Halogens

This is a group of compounds in which the atoms are particles of a gaseous substance, connected in pairs to each other through a covalent non-polar bond. However, not all halogens are gases. Bromine is a liquid under ordinary conditions, and iodine is an easily sublimated solid. Fluorine and chlorine are toxic substances that are dangerous to the health of living beings, which are strong oxidizing agents and are used very widely in syntheses.