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Chemistry as a science studies substances, their composition, structure, properties and transformations. to explain chemical processes, there are basic laws of chemistry that establish quantitative and qualitative regularities of the interaction of substances. stoichiometric laws are fundamental laws of chemistry that describe quantitative relationships between substances involved in chemical reactions. they allow you to determine in what proportions substances react, what amount of products is formed, and also help to perform calculations of mass, volume and quantity of substances.

An atom is the smallest electrically neutral particle of a chemical element that retains its chemical properties. the study of the structure of the atom is one of the most important topics in chemistry and physics, as it allows us to understand the nature of substances, the formation of chemical bonds and the regularity of the arrangement of elements in the periodic system. the modern idea of ​​an atom is based on the fact that it consists of an atomic nucleus and its surrounding electrons. most of the mass of the atom is concentrated in the nucleus, and the dimensions of the atom itself are determined by the area of ​​electron movement.

The modern understanding of the structure of the atom is based on the quantum theory, according to which the electrons in the atom are not located in certain circular orbits, but are located in special regions of space - atomic orbitals. the state of each electron in an atom is described using quantum numbers. quantum numbers allow you to determine the energy of the electron, the shape and orientation of its orbital, as well as the direction of its own rotation. the distribution of electrons by energy levels and sublevels is recorded using electronic formulas (configurations) of atoms.

The periodic law is one of the most important laws of chemistry, which explains the regularity of changes in the properties of chemical elements. it shows the connection between the structure of the atom and the arrangement of elements in the periodic table. the modern formulation of the periodic law is based on the dependence of the properties of elements on the charge of the atomic nucleus, that is, on the element's serial number.

A chemical bond is an interaction between atoms, ions or molecules that leads to the formation of stable chemical compounds. the emergence of a chemical bond is connected with the redistribution of electrons of the external energy level of atoms. the main reason for the formation of a chemical bond is the desire of atoms to reach a more stable electronic state, usually a state of a noble gas with a filled external electronic level. valence electrons — electrons of the outer shell of an atom — play an important role in the formation of chemical bonds.

Chemical kinetics is a branch of chemistry that studies the speed of chemical reactions, the mechanisms of their flow, and the factors influencing the speed change. it helps to understand why some reactions happen quickly and others slowly, as well as how to control the flow of chemical processes. chemical equilibrium is a state of reversible chemical reaction, in which the rate of forward and reverse reactions become equal, and the concentrations of substances remain constant in time. equilibrium is dynamic, as the reactions continue, but without changing the overall composition of the system.

Dispersed systems are systems in which one substance in the form of small particles is distributed in another substance. a substance that is in a fragmented state is called a dispersed phase, and the medium in which it is distributed is called a dispersion medium. the size of particles of the dispersed phase determines the properties of the system and its stability. dispersed systems are widespread in nature and are used in industry, medicine, agriculture and chemical technology.

Solutions are one of the most common forms of existence of substances in nature and are widely used in chemistry, biology, medicine and industry. their properties differ from the properties of pure substances, since the dissolved substance affects the physical characteristics of the solvent. the most important properties of solutions include osmotic pressure, a decrease in saturated vapor pressure, an increase in boiling point and a decrease in freezing point. these properties are called colligative properties, as they depend mainly on the amount of dissolved particles, and not on their chemical nature.

Electrochemistry is a branch of physical chemistry that studies the process of mutual transformation of chemical and electrical energy. electrochemical processes are the basis of the operation of accumulators, batteries, fuel cells, processes of electrolysis, corrosion of metals and methods of protecting metals from destruction. oxidation-reduction reactions occur in electrochemical processes, accompanied by the transfer of electrons from one substance to another. the ability of a substance to give or accept electrons is characterized by the electrode potential, which is an important characteristic of the chemical activity of metals.

Electrolysis is an electrochemical process in which chemical reactions occur in solutions or melts of electrolytes under the action of a constant electric current. during electrolysis, electrical energy turns into chemical energy. electrolysis is widely used in industry for obtaining metals, cleaning substances, applying protective metallic coatings and producing chemical products. the amount of substance released during electrolysis is determined by faraday's laws. accumulators are also practical applications of electrochemical processes — chemical current sources that can be repeatedly charged and discharged.

Metals play an important role in modern industry, construction, energy, transport and other spheres of human activity. most metals are found in nature in the form of compounds (ores), so various metallurgical methods are used to obtain pure metals. the choice of the method of production depends on the chemical activity of the metal, the composition of the ore and economic feasibility. during operation, metal products are exposed to the environment, which leads to their gradual destruction - corrosion. the study of the causes of corrosion and methods of protection of metals has a large meaning for increasing the service life of equipment, constructions and vehicles.

Ariflər və ticarət üzrə baş saziş (gatt — general agreement on tariffs and trade) beynəlxalq ticarətin tənzimlənməsi, gömrük rüsumlarının azaldılması və dövlətlər arasında ticarət maneələrinin aradan qaldırılması məqsədilə yaradılmış mühüm beynəlxalq sazişdir. saziş 1947-ci ildə qəbul edilmiş və 1948-ci ildə qüvvəyə minmişdir. onun əsas məqsədi dünya ticarətinin genişləndirilməsi, dövlətlər arasında iqtisadi əməkdaşlığın inkişafı və beynəlxalq ticarətdə ayrı-seçkiliyin azaldılması olmuşdur.

Light structural metals are metals with low density, high strength and good mechanical properties, widely used in industry. they are used for the manufacture of machine parts, airplanes, automobiles, space equipment, instruments and construction structures. beryllium (be) and magnesium (mg) are the most important light structural metals. due to their low weight, high strength and ability to form strong alloys, these metals are of great importance in modern technology.

Aluminum (al) and titanium (ti) are among the most important structural metals in modern industry. due to their low density, high strength, corrosion resistance and good mechanical properties, they are widely used in the aviation, space, automotive, construction and chemical industries. in nature, aluminum and titanium are found only in the form of compounds, therefore, special metallurgical methods are used to obtain pure metals. the study of their natural compounds, methods of obtaining them, physical and chemical properties has a large meaning for understanding modern technologies of production of materials.

Chromium (cr) and manganese (mn) are transition metals widely used in metallurgy, mechanical engineering, chemical industry and alloy production. they have high strength, hardness and the ability to form compounds with different degrees of oxidation. the main area of ​​their application is the production of alloyed steels and special alloys with high strength, wear resistance and corrosion resistance. in nature, chromium and manganese are found as part of minerals and ores. to obtain pure metals, metallurgical methods of restoring their compounds are used.

Iron (fe) is one of the most common and important metals in nature and industry. it is the basis of modern metallurgy and is widely used for the production of steel, cast iron and various alloys. due to its high strength, plasticity and availability, iron plays an important role in construction, mechanical engineering, transport, energy and other industries. in nature, iron is found mainly in the form of compounds (ores). metallurgical processes for the recovery of iron oxides are used to obtain pure metal. the properties of iron and its compounds determine its wide application in technology and everyday life.

Substance equivalent is one of the most important quantities in chemistry, used in quantitative calculations of chemical reactions. the equivalent shows the mass of the substance that combines with or replaces 1 mole of hydrogen atoms (or the equivalent amount of another substance). in this laboratory work, the equivalent of zinc is determined by the method of displacement of hydrogen from an acid solution. when zinc interacts with hydrochloric acid, hydrogen is released, the volume of which is measured and the equivalent mass of zinc is calculated based on the obtained data.

Determination of the molecular mass of gases is an important task of physical chemistry. one of the most common methods is the use of the equation of state of an ideal gas, which connects pressure, volume, temperature and amount of substance. in this laboratory work, the molecular mass of carbon dioxide (co₂) is determined by its mass, volume, temperature and pressure. the obtained experimental value is compared with the theoretical molecular mass, which allows you to estimate the accuracy of the measurements and master the methods of processing experimental data.

The speed of a chemical reaction is a change in the concentration of one of the reacting substances or products of the reaction per unit of time. it depends on the nature of the reacting substances and the conditions of the reaction. in this laboratory work, the influence of temperature and concentration of solutions on the speed of a chemical reaction is studied.

Lightweight structural metals are metals with low density, high strength and good technological properties, which are used to create various structures and machine parts. the most important representatives are magnesium (mg) and aluminum (al). thanks to the combination of low weight, sufficient strength, corrosion resistance and the ability to form magnesium and aluminum alloys, they are widely used in aviation, automotive, construction, electrical engineering and other industries.

Chromium (cr) and manganese (mn) belong to transition metals and are of great importance in modern metallurgy and chemical industry. they have high hardness, strength, the ability to form various compounds and improve the properties of metal alloys. chromium and manganese are mainly found in nature in the form of minerals and ores. obtaining these metals is carried out with the help of reduction processes and electrometallurgy. they found their main application in the production of steels, alloys, protective coatings and chemical products.

The goal of independent work is independent study by students of theoretical knowledge obtained during lectures and classes, use of additional scientific resources, deepening of knowledge on the topic. in the course of independent work, students investigate the essence of a given topic, analyze the main concepts, collect scientific and technical information and systematize the obtained results. in the process of work, students develop the skills of analytical thinking, searching for information, conducting analysis and inferences. self-motivated work serves to form students' ability to self-study, to connect theoretical knowledge with practical issues, and to improve professional training in their specialty.