One of the sciences that combines the content of natural and social scientific disciplines is gerontology. This science studies the aging of living organisms, including humans.
On the one hand, the object of its study is wider than the object of many scientific disciplines that study man, and on the other hand, it coincides with their objects.
At the same time, gerontology focuses primarily on the aging process of living organisms in general and humans in particular, which is its subject. It is the consideration of the object and subject of study that makes it possible to see both the general and the specific of scientific disciplines that study a person.
Since the object of study of gerontology is living organisms in the process of their aging, we can say that this science is both a natural science and social science discipline. In the first case, its content is determined by the biological nature of organisms, in the second - by the biopsychosocial properties of a person, which are in dialectical unity, interaction and interpenetration.
One of the fundamental natural science disciplines that has a direct connection with social work (and, of course, with gerontology) is medicine. This area of science (and at the same time practical activity) is aimed at preserving and strengthening people's health, preventing and treating diseases. Having an extensive system of branches, medicine in its scientific and practical activities solves the problems of maintaining health and treating the elderly. Its contribution to this sacred cause is enormous, as evidenced by the practical experience of mankind.
It should also be noted that the special significance geriatrics as a branch of clinical medicine that studies the characteristics of diseases in elderly and senile people and develops methods for their treatment and prevention.
Both gerontology and medicine are based on knowledge biology as a set of sciences about living nature (a huge variety of extinct living beings that now inhabit the Earth), about their structure and functions, origin, distribution and development, relationships with each other and with inanimate nature. The data of biology are the natural scientific basis for the knowledge of nature and the place of man in it.
Of undoubted interest is the question on the relationship between social work and rehabilitation, which plays an increasing role in theoretical research and practical activities. In its most general form, rehabilitationology can be defined as a doctrine, the science of rehabilitation as a rather capacious and complex process.
Rehabilitation (from Late Latin rehabilitation - restoration) means: firstly, the restoration of a good name, former reputation; restoration of former rights, including through administrative and judicial procedures (for example, the rehabilitation of the repressed); secondly, the application to the defendants (primarily to minors) of measures of an educational nature or punishments not related to deprivation of liberty, in order to correct them; thirdly, a set of medical, legal and other measures aimed at restoring or compensating for impaired body functions and the ability to work of patients and disabled people.
Unfortunately, representatives of industry-specific, specific scientific disciplines do not always indicate (and take into account) the latter type of rehabilitation. While social rehabilitation is of paramount importance in the life of people (restoration of the basic social functions of the individual, social institution, social group, their social role as subjects of the main spheres of society). In terms of content, social rehabilitation, in essence, in a concentrated form, includes all aspects of rehabilitation. And in this case, it can be considered as social rehabilitation in a broad sense, i.e., including all types of people's life activities. Some researchers single out the so-called vocational rehabilitation, which is included in social rehabilitation. More precisely, this type of social and labor rehabilitation could be called.
Thus, rehabilitation is one of the most important areas, technologies in social work.
To clarify the relationship between social work and rehabilitation as scientific areas, it is important to understand the object and subject of the latter.
The object of rehabilitation is certain groups of the population, individuals and strata that need to restore their rights, reputation, socialization and resocialization, restore health in general or impaired individual functions of the body. The subject of rehabilitation studies are specific aspects of the rehabilitation of these groups, the study of the patterns of rehabilitation processes. Such an understanding of the object and subject of rehabilitology shows its close connection with social work, both as a science and as a specific type of practical activity.
Social work is the methodological basis of rehabilitology. Performing the function of developing and theoretically systematizing knowledge about the social sphere (together with sociology), analyzing existing forms and methods of social work, developing optimal technologies for solving social problems of various objects (individuals, families, groups, strata, communities of people), social work as a science contributes to - directly or indirectly - the solution of issues that are the essence, the content of rehabilitation.
The close connection between social work and rehabilitation as sciences is also determined by the fact that they are essentially interdisciplinary, universal in their content. This connection, by the way, at the Moscow State University of Service was also conditioned organizationally: within the framework of the Faculty of Social Work in 1999, a new department was opened - medical and psychological rehabilitation. Medico-psychological rehabilitation and now (after the transformation of the department) remains the most important structural unit of the Department of Psychology.
Speaking about the methodological role of social work in the formation and functioning of rehabilitation, one should also take into account the influence of knowledge in the field of rehabilitation on social work. This knowledge contributes not only to the concretization of the conceptual apparatus of social work, but also to the enrichment of understanding of those patterns that socionomes study and reveal.
Concerning technical sciences, then social work is associated with them through the process of informatization, because the collection, generalization and analysis of information in the field of social work is carried out with the help of computer technology, and the dissemination, assimilation and application of knowledge and skills - other technical means, visual agitation, demonstration of various devices and devices , special clothing and footwear, etc., designed to facilitate self-service, movement along the street, housekeeping, etc. for certain categories of the population - pensioners, the disabled, etc.
Technical sciences are important in creating an appropriate infrastructure that provides an opportunity to improve the efficiency of all types and areas of social work, including the infrastructure of various spheres of life as specific objects of social work.
Chemistry - the science of the transformations of substances associated with a change in the electronic environment of atomic nuclei. In this definition, it is necessary to further clarify the terms "substance" and "science".
According to the Chemical Encyclopedia:
Substance A type of matter that has a rest mass. It consists of elementary particles: electrons, protons, neutrons, mesons, etc. Chemistry studies mainly matter organized into atoms, molecules, ions and radicals. Such substances are usually divided into simple and complex (chemical compounds). Simple substances are formed by atoms of one chemical. element and therefore are a form of its existence in a free state, for example, sulfur, iron, ozone, diamond. Complex substances are formed by different elements and may have a constant composition.
There are many differences in the interpretation of the term "science". René Descartes' (1596-1650) statement is quite applicable here: "Define the meaning of words, and you will save mankind from half of its delusions." Science it is customary to call the sphere of human activity, the function of which is the development and theoretical schematization of objective knowledge about reality; a branch of culture that did not exist at all times and not among all peoples. Canadian philosopher William Hatcher defines modern science as “a way of knowing the real world, including both the reality felt by the human senses and the invisible reality, a way of knowing based on building testable models of this reality.” Such a definition is close to the understanding of science by academician V.I. Vernadsky, the English mathematician A. Whitehead, and other famous scientists.
In scientific models of the world, three levels are usually distinguished, which in a particular discipline can be represented in a different ratio:
* empirical material (experimental data);
* idealized images (physical models);
*mathematical description (formulas and equations).
Visual-model consideration of the world inevitably leads to the approximation of any model. A. Einstein (1879-1955) said "As long as mathematical laws describe reality, they are indefinite, and when they cease to be indefinite, they lose touch with reality."
Chemistry is one of the natural sciences that studies the world around us with all the richness of its forms and the variety of phenomena occurring in it. The specifics of natural science knowledge can be defined by three features: truth, intersubjectivity and consistency. The truth of scientific truths is determined by the principle of sufficient reason: every true thought must be justified by other thoughts, the truth of which has been proven. Intersubjectivity means that each researcher should get the same results when studying the same object in the same conditions. The systematic nature of scientific knowledge implies its strict inductive-deductive structure.
Chemistry is the science of the transformation of substances. It studies the composition and structure of substances, the dependence of the properties of substances on their composition and structure, the conditions and ways of transformation of one substance into another. Chemical changes are always associated with physical changes. Therefore, chemistry is closely related to physics. Chemistry is also related to biology, since biological processes are accompanied by continuous chemical transformations.
The improvement of research methods, primarily experimental technology, led to the division of science into ever narrower areas. As a result, the quantity and "quality", i.e. the reliability of information has increased. However, the impossibility for one person to have complete knowledge even for related scientific fields has created new problems. Just as in military strategy the weakest points of defense and offensive are at the junction of fronts, in science the least developed areas remain those that cannot be unambiguously classified. Among other reasons, one can also note the difficulty in obtaining the appropriate qualification level (academic degree) for scientists working in the areas of the “junction of sciences”. But the main discoveries of our time are also being made there.
In modern life, especially in human production activities, chemistry plays an extremely important role. There is almost no industry that is not related to the use of chemistry. Nature gives us only raw materials - wood, ore, oil, etc. By subjecting natural materials to chemical processing, they obtain various substances necessary for agriculture, industrial production, medicine, everyday life - fertilizers, metals, plastics, varnishes, paints, medicinal substances , soap, etc. For the processing of natural raw materials, it is necessary to know the laws of the transformation of substances, and this knowledge is provided by chemistry. The development of the chemical industry is one of the most important conditions for technological progress.
Chemical systems
Object of study in chemistry - chemical system . A chemical system is a collection of substances that interact and are mentally or actually isolated from the environment. Completely different objects can serve as examples of a system.
The simplest carrier of chemical properties is an atom - a system consisting of a nucleus and electrons moving around it. As a result of the chemical interaction of atoms, molecules (radicals, ions, atomic crystals) are formed - systems consisting of several nuclei, in the general field of which electrons move. Macrosystems consist of a combination of a large number of molecules - solutions of various salts, a mixture of gases above the surface of a catalyst in a chemical reaction, etc.
Depending on the nature of the interaction of the system with the environment, open, closed and isolated systems are distinguished. open system A system is called a system capable of exchanging energy and mass with the environment. For example, when soda is mixed in an open vessel with a solution of hydrochloric acid, the reaction proceeds:
Na 2 CO 3 + 2HCl → 2NaCl + CO 2 + H 2 O.
The mass of this system decreases (carbon dioxide and partially water vapor escape), part of the released heat is spent on heating the surrounding air.
Closed A system is called a system that can only exchange energy with the environment. The system discussed above, located in a closed vessel, will be an example of a closed system. In this case, mass exchange is impossible and the mass of the system remains constant, but the heat of reaction through the walls of the test tube is transferred to the environment.
isolated A system is a system of constant volume in which there is no exchange of mass or energy with the environment. The concept of an isolated system is abstract, because In practice, a completely isolated system does not exist.
A separate part of the system, limited from others by at least one interface, is called phase . For example, a system consisting of water, ice and steam includes three phases and two interfaces (Fig. 1.1). The phase can be mechanically separated from the other phases of the system.Fig.1.1 - Multiphase system.
Not always the phase throughout the same physical properties and uniform chemical composition. An example is the earth's atmosphere. In the lower layers of the atmosphere, the concentration of gases is higher, and the air temperature is higher, while in the upper layers, the air is rarefied and the temperature drops. Those. the homogeneity of the chemical composition and physical properties throughout the entire phase is not observed in this case. Also, the phase can be discontinuous, for example, pieces of ice floating on the surface of the water, fog, smoke, foam - two-phase systems in which one phase is discontinuous.
A system consisting of substances in the same phase is called homogeneous . A system consisting of substances in different phases and having at least one interface is called heterogeneous .
The substances that make up a chemical system are the components. Component can be isolated from the system and exist outside of it. For example, it is known that when sodium chloride is dissolved in water, it decomposes into Na + and Cl - ions, however, these ions cannot be considered components of the system - a salt solution in water, because they cannot be isolated from a given solution and exist separately. The ingredients are water and sodium chloride.
The state of the system is determined by its parameters. Parameters can be set both at the molecular level (coordinates, momentum of each of the molecules, bond angles, etc.) and at the macro level (for example, pressure, temperature).
The structure of the atom.
Similar information.
One of the regularities in the development of natural science is the interaction of the natural sciences, the interconnection of all branches of natural science. Science is thus a single entity.
The main ways of interaction are the following:
The study of one subject at the same time by several sciences (for example, the study of man);
The use of one science of knowledge obtained by other sciences, for example, the achievements of physics are closely related to the development of astronomy, chemistry, mineralogy, mathematics and use the knowledge gained by these sciences;
Using the methods of one science to study objects and processes of another. A purely physical method - the method of "tagged atoms" - is widely used in biology, botany, medicine, etc. The electron microscope is used not only in physics: it is also necessary for the study of viruses. The phenomenon of paramagnetic resonance finds application in many branches of science. In many living objects, nature has purely physical tools, for example, a rattlesnake has an organ capable of perceiving infrared radiation and capturing temperature changes by a thousandth of a degree; the bat has an ultrasonic locator that allows it to navigate in space and not bump into the walls of the caves where it usually lives, etc.;
Interaction through technology and production, carried out where data from several sciences are used, for example, in instrument making, shipbuilding, space, automation, military industry, etc.;
Interaction through the study of the general properties of various types of matter, a vivid example of which is cybernetics - the science of control in complex dynamic systems of any nature (technical, biological, economic, social, administrative, etc.) that use feedback. The management process in them is carried out in accordance with the task and continues until the management goal is achieved.
In the process of development of human knowledge, science is increasingly differentiated into separate branches that study particular issues of multifaceted reality. On the other hand, science develops a unified picture of the world, reflecting the general patterns of its development, which leads to a broader synthesis of sciences, i.e. ever deeper understanding of nature. The unity of the world lies at the basis of the unity of the sciences, towards which the development of knowledge is ultimately directed at each individual coil of human knowledge. The path to the unity of sciences lies through the integration of its individual branches, which implies the integration of various theories and research methods. Thus, in the process of development of modern sciences, the processes of differentiation are intertwined with the processes of integration of sciences: physics is divided into mechanics, and that, in turn, into kinematics, dynamics and statics; molecular, atomic, nuclear physics, thermodynamics, electricity, magnetism, optics, etc.; medical institutes train doctors of various specialties: therapists, surgeons, psychiatrists, cardiologists, ophthalmologists, urologists, etc. – the range of specializations is very wide, but any graduate of a medical institute is a doctor.
The differentiation of scientific knowledge into separate areas encourages the identification of the necessary connections between them. Many frontier sciences are emerging, for example, new branches of science have emerged on the border between physics and chemistry: physical chemistry and chemical physics (there are institutes of physical chemistry and chemical physics at the Russian Academy of Sciences (RAS) in Moscow); on the border between biology and chemistry - biochemistry; biology and physics - biophysics. By virtue of the unity of science, the integration of principles in one of its areas is necessarily connected with the integration in another. Summarizing the above, we can state the fact that the differentiation and integration of natural science is an incomplete, open process. Natural science is not a closed system, and the question of the essence of natural science becomes clearer with each new discovery.
According to the General Systems Theory (GTS), the most important property of systems with a complex structure is their hierarchy (from the Greek hierarchia - ladder of subordination), characterized by the presence of subordination or subordination of its subsystems or structural levels. Hierarchy exists in the natural sciences as well. For the first time, it was pointed out by the French physicist André Ampère (1775-1836), who tried to find the principle of natural classification of all the natural sciences known in his time. He placed physics in first place as a more fundamental science.
Ideas about the subordination of the natural sciences are widely discussed today. At the same time, there are two areas in science: reductionism(from the Latin reduction - return), according to which everything "higher" is reduced to a simpler - "lower", i.e. all biological phenomena to chemical, and chemical to physical, and integratism(everything is vice versa).
The difference between reductionism and integratism lies only in the direction of movement of the scientist's thought. In addition, the hierarchy of the main natural sciences has a cyclically closed character. cyclicality is a property inherent in nature itself. Let us give examples: the cycle of substances in Nature, the change of day and night, the change of seasons, a dying plant leaves seeds on the Earth, from which a new life then appears. Therefore, natural science, which has a single object of study - Nature, which has this property, also has it.
NATURAL SCIENCE AND HUMANITARIAN CULTURE
Culture is one of the most important characteristics of human life. Each individual is a complex biosocial system that exists through interaction with the environment. The necessary natural connections with the environment determine its needs, which are important for its normal functioning, life and development. Most human needs are met through labor.
Thus, the system of human culture can be understood as the world of things, objects created by man (his activity, labor) in the course of his historical development. Leaving aside the question of the complexity and ambiguity of the concept of culture, we can dwell on one of its simplest definitions. Culture is a set of material and spiritual values created by man, as well as the very human ability to produce and use these values.
As we can see, the concept of culture is very broad. It, in fact, covers an infinite number of the most diverse things and processes associated with human activity and its results. The diverse system of modern culture, depending on the goals of the activity, is usually divided into two large and closely related areas - material (scientific) and spiritual (humanitarian) culture. .
The subject area of the first is purely natural phenomena and properties, connections and relations of things that “work” in the world of human culture in the form of natural sciences, technical inventions and devices, industrial relations, etc. The second type of culture (humanitarian) covers the area of phenomena, in which represent the properties, connections and relationships of the people themselves, both social and spiritual (religion, morality, law, etc.).
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The phenomena of human consciousness, psyche (thinking, knowledge, evaluation, will, feelings, experiences, etc.) belong to the ideal, spiritual world. Consciousness, spiritual is very important, but only one of the properties of a complex system, which is a person. However, a person must exist materially in order to manifest his ability to produce ideal, spiritual things. The material life of people is an area of human activity, which is associated with the production of objects, things that ensure the very existence, the life of a person and satisfy his needs (food, clothing, housing, etc.).
Over the course of human history, a colossal world of material culture has been created by many generations. Houses, streets, plants, factories, transport, communication infrastructure, household institutions, the supply of food, clothing, etc. - all these are the most important indicators of the nature and level of development of society. Based on the remains of material culture, archaeologists manage to quite accurately determine the stages of historical development, the characteristics of societies, states, peoples, ethnic groups, and civilizations.
Spiritual culture is associated with activities aimed at satisfying not the material, but the spiritual needs of the individual, that is, the needs for development, improvement of the inner world of a person, his consciousness, psychology, thinking, knowledge, emotions, experiences, etc. The existence of spiritual needs and distinguishes man from animal. These needs are satisfied in the course of not material, but spiritual production, in the process of spiritual activity.
The products of spiritual production are ideas, concepts, ideas, scientific hypotheses, theories, artistic images, moral norms and legal laws, religious beliefs, etc., which are embodied in their special material carriers. Such carriers are language, books, works of art, graphics, drawings, etc.
Analysis of the system of spiritual culture as a whole makes it possible to single out the following main components: political consciousness, morality, art, religion, philosophy, legal awareness, and science. Each of these components has a specific subject, its own way of reflection, performs specific social functions in the life of society, contains cognitive and evaluative moments - a system of knowledge and a system of assessments.
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Science is one of the most important components of material and spiritual culture. Its special place in spiritual culture is determined by the value of knowledge in the way of being of a person in the world, in practice, in the material and objective transformation of the world.
Science is a historically established system of knowledge of the objective laws of the world. Scientific knowledge obtained on the basis of cognition methods tested by practice is expressed in various forms: in concepts, categories, laws, hypotheses, theories, a scientific picture of the world, etc. It makes it possible to predict and transform reality in the interests of society and man.
Modern science is a complex and diverse system of individual scientific disciplines, of which there are several thousand and which can be combined into two areas: fundamental and applied sciences.
Fundamental sciences aim at the knowledge of the objective laws of the world that exist regardless of the interests and needs of man. These include mathematical sciences, natural (mechanics, astronomy, physics, chemistry, geology, geography, etc.), humanitarian (psychology, logic, linguistics, philology, etc.). Fundamental sciences are called fundamental because their conclusions, results, theories determine the content of the scientific picture of the world.
Applied sciences are aimed at developing ways to apply the knowledge obtained by fundamental sciences about the objective laws of the world to meet the needs and interests of people. Applied sciences include cybernetics, technical sciences (applied mechanics, technology of machines and mechanisms, strength of materials, metallurgy, mining, electrical engineering, nuclear energy, astronautics, etc.), agricultural, medical, and pedagogical sciences. In applied sciences, fundamental knowledge acquires practical significance, is used to develop the productive forces of society, improve the subject sphere of human existence, and material culture.
The concept of "two cultures" is widespread in science - the natural sciences and the humanities. According to the English historian and writer C. Snow, there is a huge gap between these cultures, and scientists studying the humanities and exact branches of knowledge increasingly do not understand each other (disputes between "physicists" and "lyricists").
There are two aspects to this problem. The first is connected with the patterns of interaction between science and art, the second - with the problem of the unity of science.
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In the system of spiritual culture, science and art do not exclude, but presuppose and complement each other when it comes to the formation of a holistic, harmonious personality, the completeness of the human worldview.
Natural science, being the basis of all knowledge, has always influenced the development of the humanities (through methodology, worldview ideas, images, ideas, etc.). Without the application of the methods of the natural sciences, the outstanding achievements of modern science on the origin of man and society, history, psychology, etc. would be unthinkable. New prospects for the mutual enrichment of natural science and humanitarian knowledge open up with the creation of the theory of self-organization - synergetics.
Thus, not the confrontation of different "cultures in science", but their close unity, interaction, interpenetration is a natural trend of modern scientific knowledge.
The quality of training of engineers essentially depends on the level of their education in the field of fundamental sciences: mathematics, physics and chemistry. The role and place of chemistry in the system of natural sciences is determined by the fact that in the field of material production, a person always has to deal with matter.
In everyday life, we observe that substances undergo various changes: a steel object in humid air becomes covered with rust; firewood in the oven burns out, leaving only a small pile of ash; gasoline in a car engine burns out, while about two hundred different substances, including toxic and carcinogenic ones, enter the environment; fallen leaves of trees gradually decay, turning into humus, etc.
Knowledge of the properties of a substance, its structure, the chemical nature of its particles, the mechanisms of their interaction, the possible ways of transforming one substance into another - these problems constitute the subject of chemistry.
Chemistry is the science of substances and the laws of their transformations.
As one of the branches of natural science, chemistry is related to other natural sciences. Chemical changes are always accompanied by physical changes. The widespread use of physical research methods and mathematical apparatus in chemistry brought it closer to physics and mathematics. Chemistry is also related to biology, since biological processes are accompanied by continuous chemical transformations. Chemical methods are used to solve problems of geology. The connection between various natural sciences is very close, new sciences arise at the intersection of sciences, for example, nuclear chemistry, biochemistry, geochemistry, cosmochemistry, etc.
The study of a number of technical problems by chemical methods connects chemistry with engineering and special disciplines necessary for the practical activity of an engineer. Thus, the production of steel and other alloys, pure metals and semiconductors, the production of products from them and their further use, the operation of various mechanisms in the corresponding gas and liquid media - all this requires specific chemical knowledge and the ability to apply them in practice.
There is almost no industry that is not related to the use of chemistry. Nature gives us raw materials: wood, ore, oil, gas, etc. By subjecting natural materials to chemical processing, a person receives a variety of substances necessary for agriculture, industry, and household use: fertilizers, metals, plastics, paints, medicinal substances, soap , soda, etc. Chemistry is needed by mankind in order to obtain everything necessary from natural substances - metals, cement and concrete, ceramics, porcelain and glass, rubber, plastics, artificial fibers, pharmaceuticals. For the chemical processing of natural raw materials, it is necessary to know the general laws of the transformation of substances, and this knowledge is provided by chemistry.
In modern conditions, when it has become clear that the reserves of many natural resources are limited and cannot be restored, when the pressure on the environment from the side of man has become so great, and the ability of nature to self-cleanse is limited, a number of fundamentally new problems come to the fore, the solution of which is impossible without chemical knowledge. These primarily include issues of environmental protection and compliance with environmental requirements in new technological processes, the creation of closed production cycles and waste-free technologies, theoretical justification and development of energy and resource-saving technologies. The implementation of the requirements for high quality products and their durability is unthinkable without understanding that the control of the chemical composition is the most important stage of the technological cycle. The fight against corrosion of materials, products from them, new methods of surface treatment require an engineer to have a deep understanding of the essence of chemical processes.
The above problems can be solved by comprehensively competent engineers who, along with other tasks, are able to understand and independently navigate chemical issues.
Basic concepts of chemistry
The object of study in chemistry is the chemical elements and their compounds.
A chemical element is a type of atom with the same nuclear charge. An atom is the smallest particle of an element that has its chemical properties.
A molecule is the smallest particle of an individual substance capable of independent existence, possessing its basic chemical properties and consisting of the same or different atoms.
If molecules consist of identical atoms, then the substance is called simple or elementary., for example He, Ar, H 2 , O 2 , S 4 . A simple substance is a form of existence of a chemical element in a free state. If a molecule of a substance consists of different atoms, then the substance is called a complex (or chemical compound), for example CO, H 2 O , H 3 PO 4 .
The chemical properties of a substance characterize its ability to participate in chemical reactions, i.e., in the processes of transformation of one substance into another.
The masses of atoms and molecules are very small. For example, the masses of individual atoms are 10 -24 - 10 -22 g. The masses of atoms, molecules are expressed either in relative units (through the mass of any one particular type of atom), or in atomic mass units (amu).
1amu is 1/12 of the mass of an atom of the carbon isotope C. 1a.u.m.=1.66053*10 -24 g.
The value of the relative atomic (A r) or molecular mass (M r) shows how many times the mass of an atom or molecule is greater than 1/12 of the mass of an atom of the carbon isotope C (carbon scale of atomic masses). A r and M r are dimensionless. The values of A r are given in the periodic system of elements by D.I. Mendeleev under the element symbol. Numerically A r and A (a.m.u.) coincide. Knowing the relative atomic mass, it is easy to find the mass of an atom, expressed in grams. So, the mass of a carbon-12 atom in g is: 12 * 1.66053 * 10 -24 \u003d 1.992636 * 10 -23 g . The mass of a molecule is equal to the sum of the masses of the atoms in its composition.
The amount of matter (n; n) is the number of structural units (atoms, molecules, ions, equivalents, electrons, etc.) in the system. The unit for measuring the amount of a substance is the mole. Mole - the amount of a substance that contains as many specific structural units as there are atoms in 12 g of the carbon isotope 12 C. The number of structural units contained in 1 mole of any substance in any state of aggregation is Avogadro's constant: N A \u003d 6.02 * 10 23 mol -1 .
The amount of substance (n) is equal to the ratio of the number of structural units (atoms, molecules, ions, equivalents, electrons, etc.) in the system (N) to their number in 1 mole of the substance (N A):
Molar mass (M) is the mass of 1 mol of a substance, equal to the ratio of the mass of the substance (m) to its quantity (n):
The basic unit of molar mass is g/mol (kg/mol). The molar mass of a substance, expressed in grams, is numerically equal to the relative molecular weight of that substance.
Molar volume (V m) is the volume occupied by 1 mole of a gaseous substance, equal to the ratio of the volume of a gaseous substance (V) to its quantity ():
At n.o. (273.15 K and 101.325 kPa) for any substance in the gaseous state V m = 22.4 l / mol.
Equivalent (E) is a real or conditional particle of a substance that can replace, attach, release or be in any other way equivalent (equivalent) to one hydrogen ion in acid-base or ion-exchange reactions or to one electron in redox reactions(OVR). The equivalent is dimensionless, its composition is expressed using signs and formulas in the same way as in the case of molecules, atoms or ions.
In order to determine the formulas for the equivalent of a substance and correctly write down its chemical formula, one must proceed from the specific reaction in which this substance participates.
Consider a few examples of defining an equivalent formula:
A. 2NaOH + H 2 SO 4 \u003d 2H 2 O + Na 2 SO 4.
Brief ion-molecular equation of the process:
2OH - + 2H + \u003d 2H 2 O.
This ion exchange reaction involves two hydrogen ions. One hydrogen ion accounts for:
NaOH + 1 / 2H 2 SO 4 \u003d H 2 O + 1 / 2Na 2 SO 4,
those. one hydrogen ion corresponds to: one NaOH molecule, 1/2 H 2 SO 4 molecule, one H 2 O molecule, 1/2 Na 2 SO 4 molecule, therefore E (NaOH) \u003d NaOH; E (H 2 SO 4) \u003d 1 / 2H 2 SO 4; E (H 2 O) \u003d H 2 O; E (Na 2 SO 4) \u003d 1 / 2Na 2 SO 4.
B. Zn + 2HCl \u003d ZnCl 2 + H 2
Ion-electronic equations of oxidation, reduction processes:
Two electrons are involved in this OVR. One electron accounts for:
1/2Zn+HCl=1/2ZnCl 2 +1/2H 2 ,
those. one electron corresponds to 1/2 Zn atom, one HCl molecule, 1/2 ZnCl 2 molecule and 1/2 H 2 molecule, therefore E(Zn) = 1/2Zn; E(HCl) = HCl; E (ZnCl 2) \u003d 1/2ZnCl 2; E (H 2) \u003d 1 / 2H 2.
The number indicating what fraction of a real particle is equivalent to one hydrogen ion or one electron is called the equivalence factor f e. For example, in the considered reactions f e (Zn)=1/2, f e (NaOH)=1.
For redox reactions, the concept is used "equivalent number" (Z), which is equal to the number of electrons attached by one molecule of the oxidizing agent or donated by one molecule of the reducing agent.
Mole equivalent - the amount of a substance containing 6.02 * 10 23 equivalents. The mass of one mole of the equivalent of a substance is called the molar mass of the equivalent of a substance (M e), measured in g / mol and calculated by the formulas:
M e \u003d m / n e; M e \u003d f e * M,
where M is the molar mass of the substance, g/mol; ν e - the amount of the equivalent of a substance, mol.
The following formulas can be used to calculate the molar mass equivalent of a substance:
1. For a simple substance:
M e \u003d M A / B, f e \u003d 1 / B,
where M A is the molar mass of atoms of a given substance; B is the valency of the atom, for example, M e (Al) \u003d 27/3 \u003d 9 g / mol.
2. For a complex substance:
M e \u003d M / B * n, f e \u003d 1 / B * n,
where B is the valency of the functional group; n is the number of functional groups in the formula of a substance molecule.
For acids, the functional group is the hydrogen ion; for bases, the hydroxyl ion; for salts, the metal ion; for oxides, the oxide-forming element.
M e acid \u003d M acid / basicity of the acid.
The basicity of an acid is determined by the number of protons that an acid molecule donates when it reacts with a base..
For example, M e (H 2 SO 4) \u003d 98/2 \u003d 49 g / mol.
M e base \u003d M base / acidity of the base.
The acidity of a base is determined by the number of protons attached to the base molecule when it interacts with an acid.
For example, M e (NaOH)=40/1=40 g/mol.
M e salt \u003d M salt / (number of metal atoms * metal valence).
For example, M e (Al 2 (SO 4) 3) \u003d 342 / (2 * 3) \u003d 57 g / mol.
M e oxide \u003d M oxide / (number of atoms of the oxide-forming element * valency of the element).
For example, M e (Al 2 O 3) \u003d 102 / (2 * 3) \u003d 17 g / mol.
In general, the molar mass of the equivalent of a chemical compound is equal to the sum of the molar masses of the equivalents of its constituent parts.
3. For an oxidizing agent, reducing agent:
where Z is an equivalent number (Z=1/f e).
As you know, a mole of any gas under normal conditions (T = 273.15 K, P = 101.325 kPa or 760 mm Hg) occupies a volume equal to 22.4 liters; this volume is called the molar volume V m. Based on this value, you can calculate the volume of one mole of gas equivalent (V e, l / mol) under normal conditions. For example, for hydrogen E (H 2) \u003d 1 / 2H 2, a mole of hydrogen equivalent is half its mole of molecules and therefore the volume of one mole of hydrogen equivalent is also two times less than its molar volume: 22.4 l / 2 \u003d 11, 2 l. For oxygen E (O 2) \u003d 1/4 O 2, hence the volume of one mole of oxygen equivalent is four times less than its molar volume: 22.4 l / 4 \u003d 5.6 l.
In general: V e \u003d f e * V m; V e \u003d V /.
Basic laws of chemistry
1. The law of conservation of mass of substances(M.V. Lomonosov; 1756):
the mass of the substances that entered into the reaction is equal to the mass of the substances formed as a result of the reaction.
2. The law of constancy of composition.
It has various formulations:
The composition of the compounds of the molecular structure is constant regardless of the method of preparation (more accurate modern formulation);
- any complex substance, regardless of the method of its preparation, has a constant qualitative and quantitative composition;
The ratios between the masses of the elements that make up a given compound are constant and do not depend on the method of obtaining this compound.
3. Law of multiple ratios(Dalton, 1803):
if two elements form several chemical compounds with each other, then the masses of one of the elements per the same mass of the other in these compounds are related to each other as small integers.
The law testified that the elements are included in the compounds only in certain portions, confirmed atomistic ideas. The smallest amount of an element that enters into a compound is an atom. Therefore, only an integer number of atoms, and not a fractional one, can enter into a compound. For example, the mass ratios of C:O in oxides of CO 2 and CO are 12:32 and 12:16. Therefore, the mass ratio of oxygen associated with the constant mass of carbon in CO 2 and CO is 2:1.
4. Law of Volumetric Relations(Gay-Lussac's law):
the volumes of reacting gases are related to each other and to the volumes of gaseous reaction products formed as small integers.
5.Avogadro's law( 1811) :
equal volumes of any gases taken at the same temperature and at the same pressure contain the same number of molecules. Avogadro's constant N A \u003d 6.02 * 10 23 mol -1 - the number of structural units in one mole of a substance.
Consequences from Avogadro's law:
A) at a certain temperature and pressure, 1 mole of any substance in the gaseous state occupies the same volume;
b) at n.o.s. (273.15 K and 101.325 kPa) the molar volume (V m) of any gas is 22.4 l mol.
6. The equation of state of an ideal gas - Mendeleev-Clapeyron:
where P is the gas pressure, Pa; V is the volume of gas, m 3; m is the mass of the substance, g; M is its molar mass, g/mol; T is the absolute temperature, K; R is the universal gas constant, equal to 8.314 J/mol*K.
7. Partial pressure law(Dalton's law):
The pressure of a mixture of gases that do not chemically interact with each other is equal to the sum of the partial pressures of the gases that make up the mixture.
8. The law of equivalents.
It has several expressions:
1) the masses of the substances involved in the reaction are proportional to their molar mass equivalents:
m 1 / m 2 = M E1 / M E2 = ...;
2) all substances react with each other in equivalent quantities, those. the number of moles of the equivalent of the substances involved in the reaction are equal to each other:
ν e1 = ν e2 = ...;
m 1 / M E1 \u003d m 2 / M E2 \u003d .... .
3) for reactants in solution, law of equivalents are written as follows:
S E 1 * V 1 \u003d C E 2 * V 2,
where C e 1, C e 2 - normal concentrations or molar concentrations of the equivalent of the first and second solutions, mol / l; V 1 and V 2 - volumes of reacting solutions, l.
