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Answer from OLIA xxxxxxx[guru]

Answer from Ekaterina Volkova[newbie]
Solutions are a homogeneous multicomponent system consisting of a solvent, solutes and products of their interaction.
According to the state of aggregation, solutions can be liquid (sea water), gaseous (air) or solid (many metal alloys).
Particle sizes in true solutions are less than 10-9 m (of the order of molecular sizes).
Unsaturated, saturated and supersaturated solutions
If the molecular or ionic particles distributed in a liquid solution are present in it in such quantity that, under given conditions, no further dissolution of the substance occurs, the solution is called saturated. (For example, if you put 50 g of NaCl in 100 g of H2O, then only 36 g of salt will dissolve at 200C).
A saturated solution is a solution that is in dynamic equilibrium with an excess of solute.
By placing less than 36 g of NaCl in 100 g of water at 200C, we get an unsaturated solution.
When a mixture of salt and water is heated to 1000C, 39.8 g of NaCl will dissolve in 100 g of water. If the undissolved salt is now removed from the solution, and the solution is carefully cooled to 200C, the excess salt does not always precipitate. In this case, we are dealing with a supersaturated solution. Supersaturated solutions are very unstable. Stirring, shaking, adding grains of salt can cause the excess salt to crystallize and transition to a saturated stable state.
An unsaturated solution is a solution that contains less of a substance than a saturated solution.
A supersaturated solution is a solution that contains more of a substance than a saturated solution.
Dissolution as a physical and chemical process
Solutions are formed by the interaction of a solvent and a solute. The process of interaction between a solvent and a solute is called solvation (if the solvent is water, hydration).
The dissolution proceeds with the formation of products of various shapes and strengths - hydrates. At the same time, forces of both physical and chemical nature are involved. The dissolution process due to this kind of interaction of components is accompanied by various thermal phenomena.
The energy characteristic of dissolution is the heat of formation of the solution, considered as the algebraic sum of the thermal effects of all endo- and exothermic stages of the process. The most significant among them are:
- heat-absorbing processes - destruction of the crystal lattice, breaks of chemical bonds in molecules;
- heat-releasing processes - the formation of products of interaction of a dissolved substance with a solvent (hydrates), etc.
If the energy of destruction of the crystal lattice is less than the energy of hydration of the dissolved substance, then the dissolution proceeds with the release of heat (heating is observed). Thus, the dissolution of NaOH is an exothermic process: 884 kJ/mol is spent on the destruction of the crystal lattice, and 422 and 510 kJ/mol are released during the formation of hydrated Na+ and OH- ions, respectively.
If the energy of the crystal lattice is greater than the energy of hydration, then the dissolution proceeds with the absorption of heat (when preparing an aqueous solution of NH4NO3, a decrease in temperature is observed).
Solubility
The limiting solubility of many substances in water (or other solvents) is a constant value corresponding to the concentration of a saturated solution at a given temperature. It is a qualitative characteristic of solubility and is given in reference books in grams per 100 g of solvent (under certain conditions).
Solubility depends on the nature of the solute and solvent, temperature and pressure.
The nature of the solute. Crystalline substances are divided into:
P - highly soluble (more than 1.0 g per 100 g of water);
M - slightly soluble (0.1 g - 1.0 g per 100 g of water);
H - insoluble (less than 0.1 g per 100 g of water).

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Introduction. 2

Paper and pencils. eleven

Glass. thirteen

Soaps and detergents. 17

Chemical means of hygiene and cosmetics. 20

Chemistry in agriculture. 24

Candle and light bulb. 26

Chemical elements in the human body. 29

References. 33

Introduction

Everywhere, wherever you look, we are surrounded by objects and products made from substances and materials that are obtained in chemical plants and factories. Besides, in Everyday life, without suspecting it, each person carries out chemical reactions. For example, washing with soap, washing with detergents, etc. When a piece of lemon is lowered into a glass of hot tea, the color fades - tea here acts as an acid indicator, similar to litmus. A similar acid-base interaction occurs when wetting chopped blue cabbage with vinegar. Mistresses know that cabbage turns pink at the same time. Lighting a match, kneading sand and cement with water, or extinguishing lime with water, firing bricks, we carry out real, and sometimes quite complex chemical reactions. The explanation of these and other chemical processes that are widespread in human life is the lot of specialists.

Cooking is also a chemical process. No wonder they say that women chemists are often very good cooks. Indeed, cooking in the kitchen is sometimes like doing organic synthesis in a lab. Only instead of flasks and retorts in the kitchen they use pots and pans, but sometimes autoclaves in the form of pressure cookers. It is not necessary to list further the chemical processes that a person conducts in everyday life. It should only be noted that in any living organism various chemical reactions are carried out in huge quantities. The processes of digestion of food, respiration of animals and humans are based on chemical reactions. The growth of a small blade of grass and a mighty tree is also based on chemical reactions.

Chemistry is a science, an important part of natural science. Strictly speaking, science cannot surround man. It may be surrounded by the results of the practical application of science. This clarification is very significant. At present, one can often hear the words: “chemistry has spoiled nature”, “chemistry has polluted the reservoir and made it unsuitable for use”, etc. In fact, the science of chemistry has nothing to do with it. People, using the results of science, poorly formalized them into a technological process, irresponsibly reacted to the requirements of safety rules and environmentally acceptable standards for industrial discharges, ineptly and excessively used fertilizers on agricultural land and plant protection products from weeds and plant pests. Any science, especially natural science, cannot be good or bad. Science is the accumulation and systematization of knowledge. Another thing is how and for what purposes this knowledge is used. However, this already depends on the culture, qualifications, moral responsibility and morality of people who do not extract, but use knowledge.

Without chemical industry products modern man indispensable, just as it is impossible to do without electricity. The same situation is with the products of the chemical industry. It is necessary to protest not against certain chemical industries, but against their low culture.

Human culture is a complex and diverse concept, in which such categories arise as the ability of a person to behave in society, to speak his native language correctly, to keep his clothes and appearance neat, etc. However, we often talk and hear about the culture of construction, production culture management culture Agriculture etc. Indeed, when it comes to the culture of Ancient Greece or even earlier civilizations, they first of all remember the crafts that people of that era owned, what tools they used, what they knew how to build, how they knew how to decorate buildings and individual objects .

Many important chemical processes for humans were discovered long before chemistry took shape as a science. A significant number of chemical discoveries have been made by observant and inquisitive artisans. These discoveries turned into family or clan secrets, and not all of them have come down to us. Some of them were lost to mankind. It was and is necessary to spend a lot of work, create laboratories, and sometimes institutes for revealing the secrets of the ancient masters and their scientific interpretation.

Many do not know how the TV works, but they successfully use it. However, knowing the device of the TV will never interfere with anyone in its proper operation. So it is with chemistry. Understanding the essence of chemical processes that we encounter in everyday life can only benefit a person.

Water

Water on a planetary scale. Mankind has long paid great attention to water, because it was well known that where there is no water, there is no life. In dry soil, grain can lie for many years and germinate only in the presence of moisture. Despite the fact that water is the most common substance, it is distributed very unevenly on Earth. On the African continent and in Asia there are vast expanses devoid of water - deserts. A whole country - Algeria - lives on imported water. Water is delivered by ship to some coastal areas and to the islands of Greece. Sometimes there water costs more than wine. According to the United Nations, in 1985, 2.5 billion people the globe lacked clean drinking water.

The surface of the globe is 3/4 covered with water - these are oceans, seas; lakes, glaciers. In fairly large quantities, water is found in the atmosphere, as well as in the earth's crust. The total reserves of free water on Earth are 1.4 billion km 3 . The main amount of water is contained in the oceans (about 97.6%), in the form of ice on our planet there is 2.14 %. The water of rivers and lakes is only 0.29 % and atmospheric water - 0.0005 %.

Thus, water is on Earth in constant motion. The average time of its stay in the atmosphere is estimated at 10 days, although it varies with the latitude of the area. For the polar latitudes, it can reach 15, and in the middle - 7 days. The change of water in the rivers occurs on average 30 times a year, that is, every 12 days. The moisture contained in the soil is renewed in 1 year. The waters of flowing lakes are exchanged for decades, and stagnant lakes for 200-300 years. The waters of the World Ocean are renewed on average for 3000 years. From these figures, you can get an idea of ​​how much time is needed for self-cleaning of reservoirs. You just need to keep in mind that if a river flows out of a polluted lake, then the time of its self-cleaning is determined by the time of self-cleaning of the lake.

Water in the human body. It is not very easy to imagine that a person is approximately 65% ​​water. With age, the water content in the human body decreases. The embryo consists of 97% water, the body of a newborn contains 75%, and in an adult - about 60 %.

In a healthy body of an adult, a state of water balance or water balance is observed. It lies in the fact that the amount of water consumed by a person is equal to the amount of water excreted from the body. Water exchange is important integral part general metabolism of living organisms, including humans. Water metabolism includes the processes of absorption of water that enters the stomach when drinking and with food, its distribution in the body, excretion through the kidneys, urinary tract, lungs, skin and intestines. It should be noted that water is also formed in the body due to the oxidation of fats, carbohydrates and proteins taken with food. Such water is called metabolic. The word metabolism comes from the Greek, which means change, transformation. In medicine and biological science, metabolism refers to the processes of transformation of substances and energy that underlie the life of organisms. Proteins, fats and carbohydrates are oxidized in the body to form water. H 2 O and carbon dioxide (carbon dioxide) CO 2. When 100 g of fats are oxidized, 107 g of water is formed, and when 100 g of carbohydrates are oxidized, 55.5 g of water is formed. Some organisms manage only with metabolic water and do not consume it from the outside. An example is carpet moth. Do not need water in natural conditions jerboas that are found in Europe and Asia, and the American kangaroo rat. Many people know that in an extremely hot and dry climate, a camel has a phenomenal ability to go without food and water for a long time. For example, with a mass of 450 kg for an eight-day journey through the desert, a camel can lose 100 kg in mass, a then restore them without consequences for the body. It has been established that his body uses the water contained in the fluids of tissues and ligaments, and not blood, as happens with a person. In addition, camel humps contain fat, which serves as both a food store and a source of metabolic water.

The total volume of water consumed by a person per day when drinking and with food is 2-2.5 liters. Due to the water balance, the same amount of water is excreted from the body. Through the kidneys and urinary tract, about 50-60 % water. When the human body loses 6-8 % moisture in excess of the usual norm, the body temperature rises, the skin turns red, the heartbeat and breathing become more frequent, muscle weakness and dizziness appear, and a headache begins. A loss of 10% of water can lead to irreversible changes in the body, and a loss of 15-20% leads to death, because the blood thickens so much that the heart cannot cope with its pumping. The heart has to pump about 10,000 liters of blood per day. A person can live without food for about a month, and without water - only a few days. The body's response to lack of water is thirst. In this case, the feeling of thirst is explained by irritation of the mucous membrane of the mouth and pharynx due to a large decrease in humidity. There is another point of view on the mechanism of formation of this feeling. In accordance with it, a signal about a decrease in the concentration of water in the blood is sent to the cells of the cerebral cortex by nerve centers embedded in the blood vessels.

Water metabolism in the human body is regulated by the central nervous system and hormones. Violation of the function of these regulatory systems causes a violation of water metabolism, which can lead to body edema. Of course, different tissues of the human body contain different amounts of water. The richest tissue in water is the vitreous body of the eye, containing 99%. The poorest is tooth enamel. It contains only 0.2% water. A lot of water is contained in the substance of the brain.

An important function of the oceans and seas is to regulate the content of carbon dioxide (carbon dioxide) in the atmosphere. Its relative content in the atmosphere is small and amounts to only 0.03-0.04 %, However, the total mass contained in the atmosphere is very large - 2000-2500 billion tons. In connection with the development of energy, industry and transport, a huge amount of coal and oil products are burned. The main product of their oxidation is CO 2. Scientists have found that atmospheric CO 2 has the ability to delay, i.e., not let through into outer space, the thermal radiation of the Earth ("greenhouse effect"). The more CO 2 in the atmosphere, the warmer the Earth's climate. General climate warming can lead to catastrophic consequences. As a result of warming, the melting of ice at the poles of the planet and in mountainous regions will intensify, which will lead to an increase in the level of the World Ocean and to the flooding of vast areas of land. It is estimated that if all the glaciers of Greenland and Antarctica are melted, the ocean level will rise by almost 60 m. It is easy to guess that then St. Petersburg and many coastal cities will be under water. An important regulator of content CO 2 in the atmosphere is the vegetation cover of the Earth. As a result of photosynthesis, plants convert CO2 into fiber and release oxygen:

CO2+6 H2 O-> C6 H12 O 6 + 6 O2

It is appropriate to note that plants are the main suppliers of atmospheric oxygen, and its source directly or indirectly is water. The annual production of oxygen by the terrestrial vegetation of the planet is 300 billion tons.

The main role in the regulation of content CO 2 oceans play in the atmosphere. An equilibrium is established between the oceans and the Earth's atmosphere: carbon dioxide CO 2 dissolves in water to form carbonic acid H 2 CO 3, and further turns into bottom carbonate sediments. The fact is that sea water contains calcium and magnesium ions, which, with a carbonate ion, can turn into sparingly soluble calcium carbonate. CaCO 3 and magnesium MgCO3. Many marine organisms extract the first salt from sea water and build shells from it. When these organisms die off over long periods of time, huge accumulations of shells form at the bottom. This is how chalk deposits are formed, and as a result of secondary geological transformations - limestone deposits, often in the form of rubble slabs. Both chalk and rubble stone are widely used in the construction industry.

The green cover of the Earth cannot cope with the task of keeping at about the same level of content CO 2 in the atmosphere. It is estimated that terrestrial plants annually consume 20 billion tons from the atmosphere to build their bodies. CO 2, and the inhabitants of the oceans and seas extract 155 billion tons from the water in terms of CO 2 .

No less important substance in creating the "greenhouse effect" than CO 2, is atmospheric water. It also intercepts and absorbs the thermal radiation of the Earth. However, there is much more of it in the atmosphere than carbon dioxide. Atmospheric moisture, especially in the form of clouds, is sometimes compared to the "blanket" of the planet. Many have noticed that with a clear and cloudless sky, the nights are colder than in cloudy weather.

The main consumers of fresh water are: agriculture (70%), industry, including energy (20 %) and utilities (~ 10%). In industrial production, the most water-intensive are the chemical, pulp and paper and metallurgical industries. So, for the manufacture of I tons of synthetic fiber, 2500-5000 are spent, plastics - 500-1000, paper - 400-800, steel and cast iron - 160-200 m 3 of water. Experience shows that a resident of a well-organized city spends 200-300 liters of water per day for domestic needs. The distribution of water consumption on average is as follows: only 5% is spent on cooking and drinking, 43% in the flushing tank of the toilet, 34% for bathing and showering, 6% for washing dishes, 4% for laundry, and 3% for cleaning the premises. %.

Natural water can be used for cooking and drinking if it does not contain harmful microorganisms, as well as harmful mineral and organic impurities, if it is transparent, colorless and has no taste or smell. In accordance with the State Standard, the content of mineral impurities should not exceed 1 g/l. The acidity of water in pH units should be in the range of 6.5-9.5. The concentration of nitrate ion should not exceed 50 mg/l. Naturally, it must also meet bacteriological requirements and have acceptable indicators for toxic chemical compounds. Well and spring water most often satisfies these requirements. However, it is difficult to find water that meets the State standard in large quantities. Therefore, it has to be cleaned at special stations. The main purification steps are filtration (through a layer of sand) and treatment with oxidizing agents (chlorine or ozone). In some cases, it is necessary to use coagulation. For this, aluminum sulfate A1 2 (SO 4) 3 is used. In a slightly alkaline environment created by calcium carbonates, under the action of water, this salt is hydrolyzed and a flocculent precipitate of aluminum hydroxide Al (OH) 3 is obtained from it, as well as calcium sulfate CaSO4 according to the equation

Al 2 ( SO 4) 3 + ZCa (HCO 3) 2 = 2 AI (OH) 3 ↓ + 3 CaSO 4 ↓ + 6CO 2

aluminum hydroxide A1(OH) 3 at first it is formed in the form of small colloidal particles, which eventually combine into larger ones. This process is called coagulation. When coagulating flakes A1(OH) 3 they capture suspended impurities and sorb organic and mineral substances on their developed surface.

For a long time, simple boiling was used to sterilize drinking water, and the ancient Greeks added dry wine to the water, which created an acidic environment in which many pathogenic microbes died.

Drinking water should contain small amounts of dissolved salts and gases. Depending on them, water tastes different in different places. macro components chemical composition surface and some underground waters are considered ions Na + , K + , Mg2+, Ca 2+ , SO 4 , C l, NO 3. ions Fe2+, Fe3+, Al 3+ in appreciable quantities are contained only in local groundwater, characterized by an acidic environment. Silicic acid H2 SiO3 it is the predominant component in some types of ground and surface waters with very low salinity, as well as in thermal waters. The boundary between fresh and mineral water is considered to be the content of mineral chemical compounds in the amount of 1 g/l.

Natural waters containing salts, dissolved gases, organic substances in higher concentrations than drinking water are called mineral. Some of the mineral waters contain biologically active components: CO 2 H2 S, some salts (for example, sodium and magnesium sulfates), arsenic compounds, radioactive elements (for example, radon), etc. Therefore, mineral waters have long been used as a remedy. Currently, mineral waters are divided into medicinal, medical-table and table waters.

Medicinal mineral waters show their effect in some cases when used externally, and in others when used internally. Of course, waters suitable for internal use are sometimes useful for external use. Hydrogen sulfide waters are widely known as medicinal waters (for example, waters in the area of ​​​​the Matsesta resort), Borjomi is best known as medicinal table water, and Narzan and Essentuki No. 20 are best known as table waters. In various regions of our country, various local mineral waters are widely used as canteens, for example, in St. Petersburg, Polustrovo water is known. Before bottling, table mineral waters are usually additionally saturated with carbon dioxide to a concentration of 3-4 %.

Distilled water, obtained by condensation of steam, contains practically no salts and dissolved gases and therefore has an unpleasant taste. In addition, with prolonged use, it is even harmful to the body. This is due to the washing out of the cells of the tissues of the stomach and intestines of the salts and microelements contained in them, which are necessary for the normal functioning of the body.

Since water is a very good solvent, in nature it always contains solutes, since there are no absolutely insoluble substances. Their number and nature depend on the composition of the rocks with which the water was in contact.

The smallest amount of impurities and dissolved substances is found in rainwater. However, even it contains dissolved gases, salts and solid particles. The salts contained in rainwater have their origin in the oceans and seas. Bursting bubbles on the surface of the oceans release a fairly large amount of salt into the atmosphere. They are captured by air currents (especially in stormy weather) and distributed in the atmosphere. The solid residue that forms when rainwater evaporates is dust particles captured by raindrops. Of 30 liters of rainwater, evaporation leaves approximately 1 g of dry residue. Dissolved gases are both the main components of the air and the pollution found in the area. The composition of rainfall over the sea is consistent with the rule that it is identical to that obtained by adding 1.5 ml of sea water to 1 liter of distilled water.

Obtaining high-purity water is a very difficult task. Since it is stored in some kind of vessel, it must contain impurities of the material of this vessel (whether it be glass or metal). For precision scientific research, the purest water is obtained by rectification (distillation) of distilled water in fluoroplastic columns.

The main reserves of fresh water on Earth are concentrated in glaciers.

Air humidity.

An important characteristic of the state of the atmosphere is the humidity of the air or, what is the same, the degree of saturation of the air with water vapor. It is expressed as the ratio of the content of water vapor in the air to their content when the air is saturated at a given temperature. Therefore, it is more correct to speak not just about humidity, but about relative humidity. When the air is saturated with water vapor, the water in it no longer evaporates. For humans, the most favorable air humidity is 50%. Humidity, like many other things, is subject to the rule: too much and too little - equally bad. Indeed, with high humidity, a person feels low temperatures more sharply. Many could see that severe frosts with low air humidity are more easily tolerated than less severe ones, but with high humidity. The fact is that water vapor, like liquid water, has a much higher heat capacity than air. Therefore, in humid air the body gives off more heat to the surrounding space than in a dry one. In hot weather, high humidity again causes discomfort. Under these conditions, the evaporation of moisture from the surface of the body decreases (a person sweats), which means that the body cools worse and, therefore, overheats. In very dry air, the body loses too much moisture and if it cannot be replenished, this affects the well-being of a person.

Absolutely dry air practically does not exist.

In 1913, the English chemist Baker found that liquids dried for nine years in sealed ampoules boil at much more high temperatures oh, than indicated in the reference books. For example, benzene begins to boil at a temperature of 26 ° above normal, and ethyl alcohol - at 60, bromine - at 59, and mercury - almost 100 °. The freezing point of these liquids has increased. The effect of water traces on these physical characteristics has not yet been satisfactorily explained. It is now known that thoroughly dried gases NH3 and HG1 do not form ammonium chloride, and dry NH 4 C1 in the gas phase does not dissociate into NH3 and HC1 when heated. Acidic sulfur trioxide does not interact with basic oxides in dry conditions Cao, Bao, CuO, and alkali metals do not react with either anhydrous sulfuric acid or anhydrous halogens.

In well-dried oxygen, coal, sulfur, and phosphorus burn at a temperature much higher than their combustion temperature in undried air. Moisture is believed to play a catalytic role in these chemical reactions.

A very rare property of water is manifested during its transformation from a liquid to a solid state. This transition is associated with an increase in volume and, consequently, with a decrease in density.

Scientists have proven that water in the solid state has an openwork structure with cavities and voids. When melted, they are filled with water molecules, so the density of liquid water is higher than the density of solid water. Since ice is lighter than water, it floats on it rather than sinking to the bottom. It plays a very important role in nature. If the density of ice were higher than that of water, then, having appeared on the surface due to the cooling of water by cold air, it would sink to the bottom and, as a result, the entire reservoir would have to freeze. This would have a catastrophic effect on the life of many organisms in water bodies.

It is interesting that if you create over water high pressure and then cool it to freezing, then the ice formed under conditions of increased fission will melt not at 0 0 C, but at a higher temperature. So, ice obtained by freezing water, which is under a pressure of 20,000 atm., Under normal conditions, melts only at 80 0 C.
Salt

Salt starvation can lead to the death of the body. The daily requirement for salt in an adult is 10-15 g. In a hot climate, the need for salt increases to 25-30 g.

Sodium chloride is needed by the human or animal body not only for the formation of hydrochloric acid in gastric juice. This salt is included in tissue fluids and in the composition of the blood. In the latter, its concentration is 0.5-0.6 %.

Aqueous solutions NaCI in medicine, they are used as blood-substituting fluids after bleeding and in cases of shock. Content reduction NaCI in blood plasma leads to metabolic disorders in the body.

Not getting NaCI from the outside, the body gives it from the blood and tissues.

Sodium chloride contributes to the retention of water in the body, which, in turn, leads to an increase blood pressure. Therefore, with hypertension, obesity, edema, doctors recommend reducing the daily intake of salt. excess in the body NaCI can cause acute poisoning and lead to paralysis of the nervous system.

The human body quickly reacts to the violation of the salt balance by the appearance of muscle weakness, fatigue, loss of appetite, the appearance of unquenchable thirst.

Table salt has albeit weak, but antiseptic properties. The development of putrefactive bacteria stops only when its content is 10-45 %. This property is widely used in the food industry and in food preservation at home.

During the evaporation of sea water at temperatures of 20-35 ° C, the least soluble salts are first released - calcium and magnesium carbonates and calcium sulfate. Then more soluble salts precipitate - sodium and magnesium sulfates, sodium, potassium, magnesium chlorides, and after them potassium and magnesium sulfates. The order of crystallization of salts and the composition of the precipitates formed may vary somewhat depending on temperature, evaporation rate, and other conditions.

Salt exposed to moist air becomes damp. Pure sodium chloride is a non-hygroscopic substance, that is, it does not attract moisture. Magnesium and calcium chlorides are hygroscopic. Their impurities are almost always found in table salt and due to them moisture is absorbed.

In the earth's crust, layers of rock salt are quite common. Table salt is the most important raw material for the chemical industry. Soda, chlorine, hydrochloric acid, sodium hydroxide, metallic sodium are obtained from it.

When studying the properties of soils, scientists found that, being impregnated with sodium chloride, they do not let water through. This discovery was used in the construction of irrigation canals and reservoirs. If the bottom of the reservoir is covered with a layer of earth soaked NaCl, no water leakage occurs. For this purpose, of course, technical salt is used. Builders use sodium chloride to remove the freezing of the earth in winter and turn it into hard stone. To do this, the areas of soil that are planned to be removed are densely sprinkled in autumn. NaCl. In this case, in severe frosts, these areas of the earth remain soft.

Chemists are well aware that by mixing finely ground ice with table salt, an effective cooling mixture can be obtained. For example, a mixture of composition 30 g NaCl per 100 g of ice is cooled to a temperature of -20 C 0 occurs because an aqueous solution of salt freezes at low temperatures. Therefore, ice having a temperature of about 0°C will melt in such a solution, taking away heat from the environment. This property of a mixture of ice and table salt can also be successfully used by housewives.

Matches

Sparking when a stone strikes a piece of pyrite FeS 2 and setting fire to charred pieces of wood or plant fibers was a way for humans to produce fire.

Since the methods of obtaining fire were imperfect and laborious, a person had to constantly maintain a burning source of fire. To bring the fire to Ancient Rome used wooden sticks dipped in molten sulfur.

Devices for making fire, based on chemical reactions, began to be made in late XVI II in. At first, these were wood splinter, on the tip of which potassium chlorate (Bertolet's salt) was fixed in the form of a head. KS1Oz) and sulfur. The head was immersed in sulfuric acid, a flash occurred and the splinter caught fire. Man was forced to store and handle unsafe sulfuric acid, which was extremely inconvenient. Nevertheless, this chemical "tinderbox" can be considered as the progenitor of modern matches.

At the beginning of the XIX century. the German chemist Debereiner invented a more perfect, but also more complex steel. He found that a jet of hydrogen directed at spongy platinum ignites in air.

Spongy platinum plays the role of a catalyst. To use this tool in making fire in everyday life, he created a small glass device (similar to the apparatus previously invented by Kipp, which bears his name). Hydrogen was obtained by casting in contact of metallic zinc and sulfuric acid. Thus, the production of a flame and its extinguishing was ensured by turning the tap, bringing into contact (or separating) sulfuric acid and zinc. The Debereiner flint and steel can be considered the progenitor of the modern gas or gasoline lighter.

In a modern lighter, the fuel is ignited by the action of a spark resulting from the combustion of the smallest particle of “flint” cut off by a gear wheel. "Flint" is a mixture of rare earth metals (lanthanides). In a finely divided state, this mixture is pyrophoric, that is, it ignites spontaneously in air, forming a spark.

However, the earlier pyrophore was made from a mixture of potash K 2 CO 3 and dried alum K2 SO 4 ∙ Al 2 ( SO 4) 3.K finely dispersed coal or soot was added to it and heated to incandescence without air access. The powder was cooled and placed in a hermetically sealed vessel, from where it could be removed as needed. To make fire, the powder was poured onto tinder, cotton wool or rags and ignited in the air. It is believed that when calcined, finely dispersed metallic potassium is formed on the remaining particles of coal, which, oxidizing in air, serves as an ignition initiator.

The most important step on the way to modern matches was the introduction of white phosphorus into the mass of a match head (1833). Such matches were easily ignited by friction on a rough surface. However, when burned, they created an unpleasant odor and, most importantly, their production was very harmful to workers. Vapors of white phosphorus led to a serious disease - phosphorus necrosis of bones. First of all, the bones of the jaws of people were subjected to necrosis, since phosphorus penetrated through carious teeth.

In 1847, it was found that white phosphorus, when heated in a closed vessel without air access, turns into another modification - red phosphorus. It is much less volatile and practically non-toxic. Soon white phosphorus in match heads was replaced by red. Such matches were ignited only by rubbing against a special surface made of red phosphorus, glue and other substances. These matches were called safe or Swedish, since they were first made in the factory way in Sweden in 1867-1869.

There are several varieties of modern matches. By purpose, matches are distinguished that are ignited under normal conditions, moisture-resistant (designed for ignition after storage in humid conditions, for example, in the tropics), wind (lighted in the wind), etc.

Since the last century, mainly aspen and less often linden have been used as the main raw material for the manufacture of match straws. To do this, a tape is removed from a round churak, peeled from the bark, with a special knife in a spiral, which is then chopped into match straws. When a match is burned, it is necessary to obtain a non-smoldering ember from the straw and keep the red-hot slag from the burnt head on it. The need for the latter is determined by the desire to protect the consumer from burns through clothes when hot slag enters. A smoldering ember from a straw naturally poses a fire hazard. To eliminate the smoldering of the straw and fix the slag from the head, the straw is impregnated with substances that form a film on its surface during combustion. Thanks to this film, the combustion of coal stops. She also fixes the slag from the head. Phosphoric acid and its salt are used as anti-smoldering agents. ( NH 4) 2 HPO 4 .

For a period of more than 150 years, a large number of formulations of incendiary masses have been used, from which match heads are made. They are complex multicomponent systems. They include: oxidizers (KS1O 3, KgSg 2 O 7, MnO 2), giving oxygen necessary for combustion; combustible substances (sulphur, animal and vegetable glues, phosphorus sulfide P4 S3); fillers - substances that prevent the explosive nature of the combustion of the head (crushed glass, Fe 2 Oz); adhesives (adhesives), which are also combustible; acidity stabilizers ( ZnO , CaCO3 and etc.); substances that color the match mass in a certain color (organic and inorganic dyes).

In terms of the amount of oxygen released per mass part, the K 2 Cr 2 O 7 chromic peak is inferior to Bertolet salt KS lO 3, but incendiary compositions containing the first oxidizer ignite much more easily. In addition, chrompeak improves the quality of the slag.

pyrolusite MnO2 plays a dual role: a catalyst for the decomposition of Berthollet salt and a source of oxygen. Iron(III) oxide Fe2 O 3 also performs two functions. It is a mineral paint (rust color) and significantly reduces the burning rate of the mass, making burning more calm.

The combustion temperature of match heads reaches 1500 0 C, and their ignition temperature lies in the range of 180 - 200 0 C.

Phosphorus (grating) mass is also

Paper and pencils

Documents have been preserved indicating that in 105 AD. e. the minister of the Chinese emperor organized the production of paper from plants with the addition of rags. Around 800. such paper has become widespread in China, as well as in the Middle East. The acquaintance with paper of Europeans is associated with the crusades to the Middle East - to Syria, Palestine, North Africa, organized by Western European feudal lords and the Catholic Church (the first campaign took place in 1096-1099). In the early Middle Ages (before the start of the Crusades), papyrus was mainly used for writing in Europe. It was used in Italy as early as the 12th century.

Writing was known in Egypt and Mesopotamia from the end of the 4th and the beginning of the 3rd millennium BC. e., i.e., long before the invention of paper. As already noted, the main predecessors of paper as a material on which a letter was applied were papyrus and parchment.

papyrus plant ( Cyperus papyrus) grows in Egypt in a swampy area near the Nile River. The stem of the plant was stripped of bark and bast, and thin strips were cut from the snow-white material. They were laid in layers along and across, and then the vegetable juice was squeezed out of them by mechanical pressure. This juice itself has the ability to stick papyrus strips together. Later, glue made from raw hides or flour was used to fasten the strips. After drying in the sun, the resulting sheets were polished with stone or leather. Papyrus for writing began to be made about 4000 years ago. It is believed that the name of the paper ( papiera) comes from the word papyrus.

Parchment is undressed, but freed from hair and treated with lime, animal, sheep or goat skin. Just like papyrus, parchment is a strong and durable material. Although paper is less strong and durable, it is cheaper and therefore more widely available.

Cellulose fibers in wood are bound together by lignin. Wood is boiled to remove lignin and release cellulose from it. A common cooking method is sulfite. It was developed in the USA in 1866, and the first plant using this technology was built in Sweden in 1874. The method has gained wide industrial significance since 1890. According to this method, to separate lignin and some other substances contained in wood, the latter is boiled in sulfite liquor, which consists of Ca(H SOz) 2 , H2 SO 3 and SO2 .

Binders are required to ensure the strength of the bond between the pigment particles and the base paper. Often their role is played by substances that provide paper sizing. Kaolin is widely used as mineral pigments - an earthy mass, similar in composition to clays, but in comparison with the latter, characterized by reduced plasticity and increased whiteness. One of the oldest fillers is calcium carbonate (chalk), which is why such papers are called coated. Known pigments also include titanium dioxide T iO 2 and calcium hydroxide mixture Ca(OH) 2(slaked lime) and aluminum sulfate A1 2 (SO 4) 3. The latter is essentially a mixture of calcium sulfate CaSO4 and aluminum hydroxide A1(OH)s resulting from the exchange reaction.

To make the working part of a graphite pencil, a mixture of graphite and clay is prepared with the addition of a large number hydrogenated sunflower oil. Depending on the ratio of graphite and clay, a stylus of different softness is obtained - the more graphite, the softer the stylus. The mixture is stirred in a ball mill in the presence of water for 100 hours. The prepared mass is passed through filter presses and plates are obtained. They are dried, and then a rod is squeezed out of them on a syringe press, which is cut into pieces of a certain length. The rods in special devices are dried and the curvature that has arisen is corrected. Then they are fired at a temperature of 1000-1100°C in shaft crucibles.

The composition of colored pencil leads includes kaolin, talc, stearin (it is known to a wide range of people as a material for making candles) and calcium stearate (calcium soap). Stearin and calcium stearate are plasticizers. Carboxymethylcellulose is used as a binding material. This is the glue used for wallpapering. Here it is also pre-filled with water for swelling. In addition, appropriate dyes are introduced into the leads, as a rule, these are organic substances. Such a mixture is stirred (rolled on special machines) and obtained in the form of a thin foil. It is crushed and the gun is stuffed with the resulting powder, from which the mixture is injected in the form of rods, which are cut into pieces of a certain length and then dried. To color the surface of colored pencils, the same pigments and varnishes are used, which are usually used to paint children's toys. The preparation of wooden equipment and its processing is carried out in the same way as for graphite pencils.

Glass

The history of glass goes back to ancient times. It is known that in Egypt and Mesopotamia they knew how to make it already 6000 years ago. Probably, glass began to be made later than the first ceramic products, since its production required higher temperatures than clay firing. If only clay was enough for the simplest ceramic products, then at least three components are required in the composition of glass.

In glassmaking, only the purest varieties of quartz sand are used, in which the total amount of contamination does not exceed 2-3%. Especially undesirable is the presence of iron, which, even in trace amounts (tenths of a %), stains the glass greenish. If you add soda to the sand Na 2 CO3, then it is possible to weld glass at a lower temperature (by 200-300 °). Such a melt will be less viscous (bubbles are more easily removed during cooking, and products are easier to form). But! Such glass is soluble in water, and products from it are subject to destruction under the influence of atmospheric influences. To make the glass insoluble in water, a third component is introduced into it - lime, limestone, chalk. All of them are characterized by the same chemical formula - CaCO 3 .

Glass, the initial charge components of which are quartz sand, soda and lime, is called sodium-calcium. It makes up about 90% of the glass produced in the world. When boiled, sodium carbonate and calcium carbonate decompose according to the equations:

Na 2 CO 3 → Na 2 O + CO 2

CaCO3 → Sao + CO 2

As a result, the glass contains oxides SiO 2 , Na 2 O and Cao. They form complex compounds - silicates, which are sodium and calcium salts of silicic acid.

In glass instead Na 2 O you can successfully enter K 2 O, a Cao can be replaced MgO , PbO , ZnO BaO. Part of the silica can be replaced by boron oxide or phosphorus oxide (by introducing compounds of boric or phosphoric acids). Each glass contains some alumina Al 2 O 3 coming from the walls of the glass melting vessel. Sometimes it is added on purpose. Each of these oxides provides glass with specific properties. Therefore, by varying these oxides and their quantity, glasses with desired properties are obtained. For example, boric acid B 2 O 3 leads to a decrease in the coefficient of thermal expansion of glass, which means it makes it more resistant to sudden temperature changes. Lead greatly increases the refractive index of glass. Alkali metal oxides increase the solubility of glass in water, so glass with a low content of them is used for chemical glassware.

The coloring of glass is carried out by introducing into it oxides of certain metals or by the formation of colloidal particles of certain elements. Thus, gold and copper, when colloidally distributed, color glass red. Such glasses are called gold and copper ruby, respectively. Silver in the colloidal state turns glass yellow. Selenium is a good dye. In the colloidal state, it colors the glass pink, and in the form of the CdS 3CdSe compound, it turns red. Such glass is called selenium ruby. When stained with metal oxides, the color of glass depends on its composition and on the amount of dye oxide. For example, cobalt(II) oxide in small quantities gives blue glass, and in large quantities - violet-blue with a reddish tint. Copper (II) oxide in soda-lime glass gives a blue color, and in potassium-zinc glass it gives a green color. Manganese (II) oxide in soda-lime glass gives a red-violet color, and in potassium-zinc - blue-violet. Lead(II) oxide enhances the color of the glass and gives the color vibrant hues.

There are chemical and physical ways to bleach glass. In the chemical method, they strive to convert all the iron contained into Fe3+. To do this, oxidizing agents are introduced into the mixture - alkali metal nitrates, cerium dioxide SEO 2, as well as arsenic(III) oxide AS 2 O 3 and antimony(III) oxide Sb 2 O 3. Chemically bleached glass is only slightly colored (due to ions Fe3+) in a yellowish-greenish color, but has good light transmission. During physical discoloration, "dyes" are introduced into the glass, i.e. ions that color it in additional tones to the color created by iron ions - these are oxides of nickel, cobalt, rare earth elements, and also selenium. manganese dioxide MnO2 possesses the properties of both chemical and physical discoloration. As a result of double absorption of light, the glass becomes colorless, but its light transmission is reduced. Thus, it is necessary to distinguish between translucent and discolored glass, since these concepts are different.

In some palaces, ceremonial buildings and religious buildings in Europe, mica plates were inserted into small cells in window openings, which were valued very dearly. In the homes of the common people, ox bladder and oiled paper or cloth were used for this purpose. In the middle of the XVI century. even in the palaces of the French kings, windows were covered with oiled linen or paper. Only in the middle of the XVII century. under Louis XIV, glass appeared in the windows of his palace in the form of small squares inserted into a lead binding. Sheet glass of a large area could not be obtained for a long time. Therefore, even in the XVIII century. glazed windows had small binding. Pay attention to the restored buildings of the Petrine era, such as the Menshikov Palace in St. Petersburg. But back to the origins of the production of window glass.

At the end of the medieval period in Europe, the “lunar” method of making sheet glass began to be widely used. It was also based on the blowing method. With this method, the ball was first blown out, then it was flattened, an axis was soldered to its bottom, and the workpiece was cut off near the blow tube. The result was something like a vase with a soldered leg-axle. The red-hot "vase" rotated at high speed around the axis and, under the action of centrifugal force, turned into a flat disk. The thickness of such a disk was 2-3 mm, and the diameter reached 1.5 m. Then the disk was separated from the axis and annealed. This glass was smooth and transparent. Its characteristic feature is the presence of a thickening in the center of the disk, which experts call the "navel". The lunar method of production made sheet glass available to the population. However, to replace him already at the beginning of the XVIII century. another more perfect "free" method came, which was used all over the world for almost two centuries. In essence, it was an improvement on the medieval method of blowing, which resulted in a cylinder. "Freebie" was the name given to the mass of glass formed at the end of the blow tube. It reached 15-20 kg, and as a result, sheets of glass with an area of ​​up to 2-2.5 m 2 were obtained from it.

Small glass products are made matte by treatment with hydrofluoric (hydrofluoric) acid. The latter interacts with silicon dioxide on the surface to form volatile silicon tetrafluoride SiF4 according to the equation

SiO 2 + 4 H.F.= SiF 4 + 2 H2 O

Photochromic glasses change color when exposed to radiation. At present, glasses with glasses have become widespread, which darken when illuminated, and in the absence of intense illumination again become colorless. Such glasses are used to protect strongly glazed buildings from the sun and to maintain constant illumination of premises, as well as in transport. Photochromic glasses contain boron oxide B 2 O 3, and the light-sensitive component is silver chloride AgCl in the presence of copper(I) oxide Cu 2 O. When illuminated, the process

The release of atomic silver leads to darkening of the glass. In the dark, the reaction proceeds in the opposite direction. Copper(I) oxide plays the role of a kind of catalyst.

Crystal, crystal glass is a silicate glass containing various amounts of lead oxide. Lead content is often indicated on product labels. The greater its quantity, the higher the quality of the crystal. Crystal is characterized by high transparency, good brilliance and high density. Crystal products in the hand are felt by weight.

Strictly crystal is called lead-potassium glass. Crystal glass, in which part KgO replaced by Na 2 O and part R bO replaced by CaO, MgO BaO or ZnO, is called semi-crystal.

It is believed that crystal was discovered in England in the 17th century.

Quartz glass. It is obtained by melting pure quartz sand or rock crystal, having the composition SiO2. The production of quartz glass requires a very high temperature (above 1700 °C).

Molten quartz is highly viscous and difficult to remove air bubbles. Therefore, quartz glass is often easily recognized by the prisoners in it bubbles. The most important property of quartz glass is the ability to withstand any temperature fluctuations. For example, quartz pipes with a diameter of 10-30 mm can withstand repeated heating up to 800-900 ° C and cooling in water. Quartz glass bars, cooled on one side, retain a temperature of 1500 °C on the opposite side and are therefore used as refractories. Thin-walled products made of quartz glass withstand sudden cooling in air from temperatures above 1300 °C and therefore are successfully used for high-intensity light sources. Quartz glass of all glasses is the most transparent to ultraviolet rays. This transparency is adversely affected by impurities of metal oxides and especially iron. Therefore, for the production of quartz glass, which is used for products for working with ultraviolet radiation, there are particularly stringent requirements for the purity of raw materials. In especially critical cases, silica is purified by conversion to silicon tetrafluoride SiF4(by the action of hydrofluoric acid) followed by decomposition with water into silicon dioxide SiO2 and hydrogen fluoride HF .

Quartz glass is also transparent in the infrared region.

Sitally- glass-ceramic materials obtained by controlled crystallization of glass. Glass, as you know, is a solid amorphous material. Its spontaneous crystallization in the past caused losses in production. Usually the glass melt is quite stable and does not crystallize. However, when the glass product is reheated to a certain temperature, the stability of the glass mass decreases and it turns into a fine-grained crystalline material. Technologists have learned to carry out the process of glass crystallization, excluding cracking.

Glass-ceramics have high mechanical strength and heat resistance, are waterproof and gas-tight, are characterized by low expansion coefficient, high dielectric constant and low dielectric losses. They are used for the manufacture of pipelines, chemical reactors, pump parts, spinnerets for spinning synthetic fibers, as a lining for electrolysis baths and material for infrared optics, in the electrical and electronic industries.

Strength, lightness and fire resistance led to the use of glass-ceramics in residential and industrial construction. They are used to make hinged self-supporting panels for the exterior walls of buildings, partitions, slabs and blocks for interior wall cladding, paving roads and sidewalks, window frames, balcony railings, flights of stairs, corrugated roofs, and sanitary equipment. In everyday life with sitalls, they are more often found in the form of white opaque heat-resistant kitchen utensils. It has been established that glass-ceramics withstand about 600 sharp thermal cycles. Products from glass-ceramics do not scratch and do not burn through. They can be taken off the stove in a red hot state and dipped in ice water, removed from the refrigerator and put on an open flame without fear of cracking or breaking.

Sitalls are one of the types of glass-ceramic materials that date back only to the 50s of the current century, when the first patent was issued for them.

Foam glass- porous material, which is a glass mass penetrated by numerous

voids. It has heat and sound insulation properties, low density (about 10 times lighter than brick) and high strength, comparable to concrete. Foam glass does not sink in water and is therefore used for the manufacture of pontoon bridges and life-saving equipment. However, its main area of ​​application is construction. Foam glass is an exceptionally effective material for filling the interior and exterior walls of buildings. It is easy to machine: sawing, cutting, drilling and turning on a lathe.

Glass wool and fibre. When heated, the glass softens and is easily drawn into thin and long threads. Thin glass threads have no signs of fragility. Their characteristic property is an extremely high specific tensile strength. A thread with a diameter of 3-5 microns has a tensile strength of 200-400 kg / mm 2, i.e., it approaches mild steel in this characteristic. Glass wool, fiberglass and fiberglass are made from threads. It is not difficult to guess the areas of use of these materials. Glass wool has excellent heat and sound insulation properties. Glass fiber fabrics have extremely high chemical resistance. Therefore, they are used in the chemical industry as filters for acids, alkalis and reactive gases. Due to the good fire resistance of glass fabrics, they are used for sewing clothes for firefighters and electric welders, theater curtains, draperies, carpets, etc. Glass fabrics, in addition to fire resistance and chemical resistance, also have high electrical insulating properties.

Glassware. The quality of glassware depends on the composition of the glass, the method of its production and the nature of the decorative treatment. The cheapest glass is

calcium-sodium. For dishes of improved quality, calcium-sodium-potassium glass is used, and for dishes of higher grades, calcium-potassium glass is used. The best varieties of tableware are made from crystal.

Crockery is produced by blowing or pressing. Blowing, in turn, is machine and manual. The method of production, of course, is reflected in the quality of the dishes. Complicated in shape and artistic products are made only by hand. Pressed products are easily distinguished from blown ones by characteristic small irregularities on the surface, including on the inside. They are absent on blown products.

Soaps and detergents

Soap was known to man before the new era of chronology. Scientists do not have information about the beginning of soap making in Arab countries and China. The earliest written mention of soap in European countries is found in the Roman writer and scientist Pliny the Elder (23-79). In the treatise "Natural History" (in 37 volumes), which, in essence, was an encyclopedia of the natural sciences of antiquity, Pliny wrote about methods for making soap by saponifying fats. Moreover, he wrote about hard and soft soap, obtained using soda and potash, respectively. Previously, lye was used to wash clothes, obtained from the treatment of ash with water. This was most likely before it became known that the ashes from the combustion of vegetable fuels contain potash.

Despite the fact that at the end of the Middle Ages in different countries there was a fairly developed soap industry, the chemical essence of the processes, of course, was not clear. Only at the turn of the XVIII and XIX centuries. the chemical nature of fats was clarified and clarity was brought to the reaction of their saponification. In 1779, the Swedish chemist Scheele showed that during the interaction olive oil with lead oxide and water, a sweet and water-soluble substance is formed. The decisive step towards the study of the chemical nature of fats was made by the French chemist Chevrel. He discovered stearic, palmitic and oleic acids as decomposition products of fats during their saponification with water and alkalis. The sweet substance obtained by Scheele was named glycerol by Chevrel. Forty years later, Berthelot established the nature of glycerol and explained the chemical structure of fats. Glycerin is a trihydric alcohol. Fats - esters of glycerol (glycerides) of heavy monobasic carboxylic acids, mainly palmitic CH3 (CH 2) 14 COOH, stearic CH 3 (CH 2) 16 COOH and oleic CH 3 (CH 2) 7 CH \u003d CH (CH 2) 7 COOH. Their formula and hydrolysis reaction can be described as follows:

CH 2 OOCR 1 R 1 COONa CH 2 OH

CHOOCR 2 + 3NaOH→R 2 COONa + CHOH

CH 2 OOCR 3 R 3 COONa CH 2 OH

zhirosoliglyce-

acidrin

The composition of various fats includes palmitic, stearic, oleic and other acids in various ratios. In vegetable (liquid) fats, unsaturated acids (containing ethylene bonds) predominate, and in animal (solid) fats, saturated acids, i.e., do not contain double bonds. The need for solid animal fats is greater than for vegetable fats. Therefore, liquid vegetable fats are converted into solid ones by catalytic hydrogenation. In this process, the residues of unsaturated acids in glycerides are converted (by addition of hydrogen) into residues of saturated acids. For example,

This is how cooking fats, frying oil, salad oil, as well as fats used in the production of margarine are obtained. Hydrogenated fats are called lards (lard from butter).

If you try to give a definition, then washing can be called the cleaning of a contaminated surface with a liquid containing a detergent or a system of detergents. The main liquid used in everyday life is water. A good cleaning system should perform the dual function of removing contaminants from the surface being cleaned and transferring it to an aqueous solution. This means that the detergent must also have a dual function: the ability to interact with the pollutant and transfer it to water or an aqueous solution. Therefore, the detergent molecule must have hydrophobic and hydrophilic parts. Phobospo in Greek means fear, fear. So, hydrophobic means afraid, avoiding water. Phileo - in Greek - love, and hydrophilicity - loving, holding water. The hydrophobic part of the detergent molecule has the ability to interact with the surface of the hydrophobic pollutant. The hydrophilic part of the detergent interacts with water, penetrates into the water and carries with it the contaminant particle attached to the hydrophobic end.

In the production of soap, rosin has long been used, which is obtained by processing the resin of coniferous trees. Rosin consists of a mixture of resin acids containing about 20 carbon atoms in the chain. 12-15% of rosin by weight of fatty acids is usually introduced into the recipe of laundry soap, and no more than 10% is added to the recipe of toilet soaps. %. The introduction of rosin in large quantities makes the soap soft and sticky.

The soap making process consists of chemical and mechanical steps. At the first stage (cooking of soap), an aqueous solution of sodium salts (less often potassium) of fatty acids or their substitutes (naphthenic, tar) is obtained. At the second stage, mechanical processing of these salts is carried out - cooling, drying, mixing with various additives, finishing and packaging.

Soap cooking is completed by treating the soap solution (soap glue) with an excess of alkali ( NaOH) or solution NaCl. As a result, a concentrated layer of soap, called the core, floats to the surface of the solution. The soap obtained in this way is called sound, and the process of its isolation from the solution is called salting out or salting out. When salting out, an increase in the concentration of soap and its purification from protein, coloring and mechanical impurities occurs - this is how laundry soap is obtained.

A special place among the fillers is occupied by saponin, obtained by leaching some plants and, above all, the soap root. It is highly soluble in water and its solutions foam strongly. Therefore, saponin is used to improve foaming and is used for expensive soaps.

In addition to using soap as a detergent, it is widely used in the finishing of fabrics, in the production of cosmetics, for the manufacture of polishing compounds and water-based paints. There is also a not-so-harmless use of it. Aluminum soap (aluminum salts of a mixture of fatty and naphthenic acids) is used in the United States to produce certain types of napalm, a self-igniting composition used in flamethrowers and incendiary bombs. The word napalm itself comes from the initial syllables of naphthenic and palmitic acids. The composition of napalm is quite simple - it is gasoline thickened with aluminum soap.

Currently, the chemical industry produces a large number of different synthetic detergents (washing powders). Of greatest practical importance are compounds containing a saturated hydrocarbon chain of 10-15 carbon atoms, one way or another associated with a sulfate or sulfonate group, for example

The production of synthetic detergents is based on a cheap raw material base, or rather on products of oil and gas processing. As a rule, they do not form calcium and magnesium salts, which are sparingly soluble in water.

Consequently, many of the synthetic detergents wash equally well in both soft and hard water. Some products are even suitable for washing in sea water. Synthetic detergents work not only in hot water, as is typical for laundry soap, but also in water at relatively low temperatures, which is important when washing fabrics made of artificial fibers. Finally, the concentration of synthetic detergents, even in soft water, can be much lower than soaps made from fats. Synthetic detergents usually represent a rather complex composition, since they include various additives: optical brighteners, chemical brighteners, enzymes, foaming agents, softeners.

Chemical means of hygiene and cosmetics

The word hygiene comes from the Greek. hygienos, which means healing, bringing health, and cosmetics - from Greek, meaning the art of decorating.

One way to prevent caries is to brush your teeth and rinse your mouth after eating. This leads to the prevention of the formation of soft plaque and tartar.

It is difficult to say when people started brushing their teeth, but there is evidence that one of the oldest preparations for cleaning teeth was tobacco ash.

Toothpastes are the most important means of caring for your teeth. They have a lower abrasion power compared to powders, are more convenient to use and are characterized by higher efficiency. Toothpastes are multicomponent formulations. They are divided into hygienic and treatment-and-prophylactic. The former have only a cleansing and refreshing effect, while the latter, in addition, serve to prevent diseases and contribute to the treatment of teeth and oral cavity.

The main components of toothpaste are as follows: abrasives, binders, thickeners, foaming agents. Abrasives provide mechanical cleaning of the tooth from plaque and its polishing. The most commonly used abrasives are chemically deposited chalk. CaCO 3. It has been established that the components of toothpaste are able to influence the mineral component of the tooth and, in particular, the enamel. Therefore, calcium phosphates began to be used as abrasives: Sanro 4 , Ca 3 (RO 4) 2 , Ca 2 P 2 O 7, as well as a poorly soluble polymeric sodium meta-phosphate ( NaPOz). In addition, aluminum oxide and hydroxide, silicon dioxide, zirconium silicate, as well as some organic polymeric substances, such as sodium methyl methacrylate, are used as abrasives in various types of pastes. In practice, not one abrasive substance is often used, but a mixture of them.

From synthetic substances, fiber derivatives (cotton and wood) - sodium carboxymethyl cellulose, ethoxylated ethyl and methyl cellulose ethers, or simply ethyl and methyl cellulose ethers - have found wide application.

The fight against caries with the help of therapeutic and prophylactic toothpastes is carried out in two directions: 1) strengthening the mineral tissue of the tooth; 2) prevention of plaque formation. The first is achieved by introducing fluorine compounds into the pastes: sodium monofluorophosphate, the formula of which can be conventionally written as a double salt NaF∙ NaPO 3, as well as sodium fluoride NaF and tin(II) fluoride snf 2. There are two points of view on the effect of fluoride ions on the strengthening of tooth enamel. 1. Ions F transfer enamel hydroxideapatite CaOH (RO 4) s in less soluble in acids fluoro-rapatite Ca5 F( PO 4) 2. As a result of the exchange reaction in the paste, CaF2, which is adsorbed on hydroxyapatite and protects it from acid attack. It is also known that fluoride compounds contribute to the suppression of the vital activity of bacteria that cause the formation of organic acids in the oral cavity. Currently, enzymes have become widely used in anti-caries pastes, and sometimes antibiotics are introduced into them.

Deodorants and the ozone "shield" of the planet.

Deodorants are products that eliminate the unpleasant smell of sweat. What is their action based on? Sweat is secreted by special glands located in skin at a depth of 1-3 mm. In healthy people, 98-99% of it consists of water. With sweat, metabolic products are excreted from the body: urea, uric acid, ammonia, some amino acids, fatty acid, cholesterol, trace amounts of proteins, steroid hormones, etc. Mineral components in sweat include sodium, calcium, magnesium, copper, manganese, iron ions, as well as chloride and iodide anions. The unpleasant smell of sweat is associated with the bacterial breakdown of its components or with their oxidation by atmospheric oxygen. Deodorants (cosmetics from sweat) are of two types. Some inhibit the decomposition of metabolic products excreted with sweat by inactivating microorganisms or preventing the oxidation of sweat products. The action of the second group of deodorants is based on the partial suppression of perspiration processes. Such agents are called antiperspirants. These properties have salts of aluminum, zinc, zirconium, lead, chromium, iron, bismuth, as well as formaldehyde, tannins, ethyl alcohol. In practice, among salts, aluminum compounds are most often used as antiperspirants. These substances interact with the components of sweat, forming insoluble compounds that close the channels of the sweat glands and thereby reduce sweating. Fragrances are added to both types of deodorants.

The concentration of ozone in the atmosphere depends on the content of nitrogen oxides and fluorochloromethanes. Nitrogen oxides are constantly present in low concentrations as a result of the photochemical interaction of nitrogen and oxygen. Nitric oxide (II) destroys ozone, and nitric oxide (IV) binds atomic oxygen in accordance with the equations

O 3 + NO → NO 2 + O 2

NO2+ O → NO + O 2

Oz + About → 2 O 2

Thus, nitrogen oxides play the role of catalysts in the decomposition of ozone.

During the 4.6 billion years of our planet's existence, an equilibrium has been established, and life on Earth arose and developed under a certain equilibrium composition of the atmosphere. However, the intensive development of supersonic aviation is beginning to influence the equilibrium that has been created in the atmosphere. Since supersonic aircraft are designed to fly in the stratosphere, the upper limit of which approaches the "ozone" layer, there is a danger that supersonic technology will influence this layer. During the combustion of fuel in aircraft engines, nitrogen oxides are formed in fairly large quantities.

Another source of danger to the ozone layer are fluorochloromethanes (mainly CF2 CI 2 and CFCl 3). These substances are widely used in aerosol containers, as well as refrigerants in industrial and domestic refrigerators.

Cosmetics.

In the world it is believed that among the most profitable industries in one of the first places is the cosmetic industry. Observations show that if necessary, women can deny themselves a lot, but not that which will make them at least a little more beautiful.

The art of cosmetics is a thing of the distant past. So, during the excavations, Egyptian mummies were found, the nails of which are painted. In the tombs of the Egyptian pyramids, natural paints and cosmetic tools, various tiles for preparing a mixture of paints and rouge, vessels for storing ointments and oils were found. A written document has been found - the Ebers Papyrus, which outlines cosmetic rules and recipes. Its writing is attributed to the fifth millennium BC.

Ancient manuscripts testify that already thousands of years ago, women of the East tinted their eyelids blue with the finest pollen from crushed turquoise. Turquoise is a natural mineral that has the composition With uA1 6 (RO 4) 4 (OH) 8 ∙4H 2 O .

Since time immemorial, a soft natural mineral - antimony shine has been used to tint eyebrows. Sb 2 S3. In Russian there was an expression "antimony eyebrows." Antimony glitter was supplied to various countries by the Arabs, who called it stibi. From this name came the Latin stibium, which in ancient times meant not a chemical element, but its sulfide. Sb 2 S3. Natural antimony gloss has a color from gray to black with a blue or iridescent tint.

It is reliably known that cosmetic paints were used in Russia at the end of the 16th century and especially widely in the 17th century.

The industry produces mother-of-pearl lipsticks and creams, as well as shampoos with mother-of-pearl glosses. Pearlescent effect in cosmetics is created by bismuthyl salts AT iOS l and BiO( NO 3) or titanized mica - mother-of-pearl powder containing about 40 % T iO 2. Pearl or Spanish white has long been known. Their main component is BiO( NO 3) 2 formed by dissolving bismuth nitrate Bi( NO 3)h in water. In cosmetics, this white is used to make white makeup.

Zinc oxide is used to create special cosmetics (make-ups). ZnO, obtained by calcining the basic carbonate ( ZnOH) 2 CO3. In medicine, it is used in powders (as an astringent, drying, disinfectant) and for the manufacture of ointments.

Cosmetic decorative powders are multi-component mixtures. They include: talc, kaolin, ZnO , TiO2 , MgCO3, starch, zinc and magnesium salts of stearic acid, as well as organic and inorganic pigments, in particular Fe2 O 3. Talc gives the powder flowability and a sliding effect. Its disadvantage is the ability to be absorbed into the skin and give a greasy sheen. However, it is included in the composition of powders in an amount of up to 50-80 %. Kaolin has a high hiding power and the ability to absorb excess oil from the skin. Its increased hygroscopicity contributes to caking and uneven distribution of powder on the skin, so kaolin is administered no more than 25 %. Zinc and titanium oxides have good hiding power. In addition, zinc oxide has antiseptic properties and therefore simultaneously acts as a disinfectant additive. These oxides are introduced into powders up to 15 %. In large quantities, they lead to dry skin. Starch gives the skin a velvety feel, and thanks to zinc and magnesium stearates, the powder adheres well to the skin and makes it smooth.

Compact powder, unlike loose powder, contains binding additives: sodium carboxymethylcellulose, higher fatty acids, waxes, polyhydric alcohols and their esters, mineral and vegetable oils. They make it possible to obtain briquettes of a certain shape during pressing, which retain their strength during long-term use.

In everyday life, solutions (3, 6, 10%) of hydrogen peroxide are widely used as a disinfectant and bleaching agent. More concentrated - a 30% solution of hydrogen peroxide - is called perhydrol. Hydrogen peroxide is an unstable (especially in the light) chemical compound. It decomposes into water and oxygen:

2H 2 O 2 \u003d 2H 2 O + O 2

At the moment of formation, oxygen is in the atomic state and only then goes into the molecular state:

2O \u003d O 2

Atomic oxygen has a particularly strong oxidizing property. Thanks to him, hydrogen peroxide solutions destroy dyes and bleach fabrics made of cotton and woolen fabrics, silk, feathers, and hair. The ability of hydrogen peroxide to bleach hair is used in cosmetics. It is based on the interaction of atomic oxygen with the hair dye melanin - a mixture of complex organic substances. When oxidized, melanin turns into a colorless compound. It should be remembered that perhydrol causes burns to the skin and mucous membranes.

Currently, there is a wide range of various organic dyes for hair coloring.

Sometimes salts of silver, copper, nickel, cobalt, and iron are used for this purpose. In this case, hair dyeing is carried out using two solutions. One of them contains salts of these metals: nitrates, citrates, sulfates or chlorides, and the second contains reducing agents: pyrogallol, tannin, etc. When these solutions are mixed, metal ions are reduced to atoms, which are deposited on the surface of the hair.

The most common nail polish is a solution of nitrocellulose in organic solvents. Nitrocellulose is obtained by nitrating cellulose (cotton or wood) with a mixture of nitric and sulfuric acids. It is an ester of nitric acid and is characterized by the general formula [C 6 H 7 O 2 (OH) 3- X (O NO 2) X] N. Acetic acid amyl ester, acetone, various alcohols, ethyl ether, and mixtures thereof are used as solvents. Plasticizers are added to the varnish - Castor oil or other extracts that prevent degreasing of the nails and prevent their brittleness.

Chemistry in agriculture

The Earth as a planet of the solar system exists for about 4.6 billion years. It is believed that life on it originated 800-1000 thousand years ago. Scientists have found traces of the activity of primitive man, whose age is estimated at 600-700 thousand years. The era of agriculture is only 17 thousand years old.

For millions of years, water, air, and then living organisms destroyed and crushed the rocks of the earth's crust. When dying, living organisms formed humus or, as scientists call it, humus. He mixed with crushed rock, glued and cemented it. This is how the soil on our planet was born. The first soil served as the basis for the development of subsequent larger plants, which, in turn, contributed to a new accelerated formation of humus. The process of soil formation began to proceed even more rapidly with the appearance of animals, especially those inhabiting the soil layer. The conversion of organic matter into humus was facilitated various kinds bacteria. The formation and decay of organic matter in the soil is considered the main cause of soil formation.

Thus, the soil consists of mineral and organic (humus) parts. The mineral part is from 90 to 99% or more of the total mass of the soil. It includes almost all elements of the periodic system of D. I. Mendeleev

The soil as an ion exchanger of cations is “charged” mainly with calcium ions Ca 2+, to a lesser extent - magnesium Mg2+ and, to a lesser extent, ammonium ions NH, sodium Na+ and potassium K+. Calcium ions Ca 2+ and magnesium Mg2+ contribute to maintaining a strong soil structure. Under the structure of the soil, agricultural workers understand its ability to break up into separate lumps. ions K+ or NH and especially Na+, on the contrary, contribute to the destruction of the structural aggregates of the soil and increase the leaching of humus and minerals. In wet such soil becomes sticky, and in dry conditions it turns into lumps that cannot be processed (salt soil). The water flowing out of such soil has the color of tea infusion, which indicates the loss of humus.

Of great importance is the chemical binding of anions of certain acids by the soil. Nitrate NO and chloride With l anions do not form poorly soluble compounds with cations normally found in soil.

On the contrary, anions of phosphoric, carbonic, sulfuric acids form sparingly soluble compounds with calcium ions. This determines the chemical absorption capacity of soils.

Manure.

Manure contains on average 0.5% of nitrogen bound into chemical compounds, 0.25 % phosphorus and 0.6 % potassium. The content of these nutrients depends on the type of livestock, the nature of the feed, the type of bedding and other factors. In addition to nitrogen, phosphorus and potassium, manure contains all the elements, including trace elements, necessary for plant life. Straw, sawdust are used as bedding, but peat is considered the best. Bedding allows better retention of nutrients in the manure.

mineral fertilizers.

In the world, mineral fertilizers began to be used relatively recently. The German chemist Justus Liebig was the initiator and active advocate of their use in agriculture. In 1840 he published the book "Chemistry as Applied to Agriculture". In 1841 on his initiative, the first superphosphate plant was built in England. Potash fertilizers began to be produced in the 70s of the last century. Mineral nitrogen at that time was supplied to the soil with Chilean nitrate. It should be noted that at present it is considered rational to apply phosphorus, potash and nitrogen fertilizers to the soil in terms of nutrients, approximately equal to 1:1.5:3.

Nitrogen-containing mineral fertilizers are divided into ammonia, nitrate and amide. Ammonia itself belongs to the first group NHz(anhydrous and aqueous solutions) and its salts - primarily sulfate ( NH 4) 2 SO 4 and ammonium chloride NH4 C.I. To the second group of saltpeter: sodium NaNO 3, potassium KNO 3 and calcium Ca( NO 3) 2. The industry also produces ammonium nitrate fertilizers, such as ammonium nitrate. NH4 NO 3. Amide fertilizers include calcium cyanamide CaS N 2 and urea (urea) NH2 CONH 2. To reduce the dusting of calcium cyanamide, up to 3% of petroleum oils are often added to it. As a result, this fertilizer has the smell of kerosene. Calcium cyanamide upon hydrolysis gives ammonia and calcium carbonate:

CaS N 2 + 3H 2 O \u003d CaCO3 + 2NH3

Nature has created many pantries of phosphate raw materials, including in our country. These pantries consist of apatites and phosphorites. In the group of minerals under the general name apatites, the most common phosphates of the composition Ca 5 X (PO 4) s, where X= F, Cl, OH . The corresponding minerals are called fluorapatite, chlorapatite, hydroxideapatite. The most common is fluorapatite. Apatites are part of igneous igneous rocks. Sedimentary rocks that contain apatite with inclusions of particles of foreign minerals (quartz, calcite, clay, etc.) are called phosphorites.

In plants, potassium regulates the process of respiration, promotes the absorption of nitrogen and increases the accumulation of proteins and sugars in plants. For cereals, potassium increases the strength of the straw, and in flax and hemp, it increases the strength of the fiber. Potassium increases the resistance of winter crops to frost and overwintering and vegetable crops to early autumn frosts. Potassium deficiency in plants is manifested on the leaves. Their edges become yellow and dark brown with red dots.

Other macronutrients included in nutrients.

As already noted, soils are most rapidly depleted of nitrogen, phosphorus and potassium. In addition to them, plants need other chemical elements in fairly large quantities: calcium, magnesium, sulfur, iron. Their content in soils is often close to the needs of plants and their removal with marketable products is relatively low.

Microfertilizers.

Microfertilizers are called nutrients that contain chemical elements consumed by plants in very small quantities. At present, the biological role of boron, copper, manganese, molybdenum, etc. in the life of plant and animal organisms has been revealed. Fertilizers containing these trace elements have received appropriate names.

Candle and light bulb

Nowadays, buying a candle is available to everyone in almost the same way as matches. However, this was not always the case. At the beginning of the last century in Russia, candles were valued very dearly, and in the homes of ordinary people, a torch or a lamp with oil was usually burned. Kerosene lamps came later. The generosity of people was judged by the size of the candle lit by a person when visiting a church.

In the last century, the production of candles was a developed industry. There were descriptions of production technologies and their chemical nature. In particular, such work in 1851. was written by the teacher of the St. Petersburg Institute of Technology N. Witt.

From his book we learn that the candles were wax, tallow, stearin, spermaceti and very expensive paraffin. About the materials from which the candles were prepared will be discussed below. However, not immediately about this. It is impossible not to recall that in the middle of the last century, the great English scientist Michael Faraday gave a lecture on the topic. Candle History. It was an inspired hymn to the creation of man and nature. The lecture was translated into Russian and part of it was published. The author recommends that anyone interested in physics and chemistry read this outstanding work.

Probably the first candles were made of wax. Beeswax is a gift of nature and a candle could be made from it in the most primitive way. Much later, the wax began to be cleaned. The technology was again very simple. This was achieved by melting the wax and filtering the molten state through a cloth. Bone charcoal, sulfur dioxide or chlorine were used to bleach the wax, depending on the possibilities.

It should be noted that vegetable wax was brought to Europe from the American continents. It was used to make candles instead of bee, but it was much more expensive and therefore could not stand the competition.

Candle threads were boiled for several hours in lye made from potash and burnt lime. This was followed by washing with water and bleaching with bleach.

Stearin was originally understood as two different products extracted from beef and mutton fat. One of them was obtained by removing liquids from fat by pressing. The solid residue was called stearin. Another product was obtained by chemical treatment of fat, first with lime and then with sulfuric acid. In essence, it was the hydrolysis of fats (glycerides) followed by the isolation of a mixture of acids: stearic, palmitic and a small amount of unsaturated acids.

Stearic acid CH 3 (CH 2) 16 COOH was discovered in Sala in 1816. French chemist Chevrel. Together with Gay-Lussac in 1825. he took in England the privilege of making stearin candles.

Stearin candles are cheaper than wax candles. However, the Russian Church for a long time did not agree to replace wax candles with stearin ones. One of the reasons was that wax candles emitted a pleasant smell when burned.

Tallow candles were made from melted tallow, which was then cleaned mechanically (by filtering through a cloth) or chemically (with alumina or tannins) and discolored in the same way as wax. When burning, tallow candles smoked heavily.

Spermaceti for spermaceti suppositories was extracted from the cavities in the heads of whales. It was freed from accompanying liquid oils by cold or hot pressing. If necessary, cleaning was carried out with soap lye. Candles made from spermaceti were white and translucent. However, they also had a drawback. When burned, they melted over time.

In the current century, before the extermination of whales, scarce spermaceti was used mainly as a base for creams and various ointments, as well as a high-quality lubricating oil for precision instruments.

Paraffin candles were initially quite expensive, since paraffin was extracted by distilling the tar of plant matter. Then in England it began to be mined from peat. However, in both cases, it was obtained only in small quantities. A fundamental change occurred with the establishment of large-scale oil refining. Now it is one of the most accessible petrochemical products. Paraffin - a mixture of saturated hydrocarbons From 18 - From 35. A mixture of saturated hydrocarbons C 36 -C 55 called ceresin. Modern candles are made from a mixture of paraffin and ceresin.

The light bulb consists of a glass container into which the holders of the spiral are inserted, and of the spiral itself. The spiral is made of tungsten - one of the most refractory metals. Its melting point is 3410 °C. In addition to high refractoriness, tungsten has another very important property - high ductility. From 1 kg. tungsten can be used to draw a wire 3.5 km long, which is enough to make 23,000 60-watt light bulbs. The holder is made of molybdenum, an analogue of tungsten. In the periodic system of D. I. Mendeleev, these two elements are in the same subgroup. The most important property of molybdenum is a small coefficient of linear expansion. When heated, it expands in size in the same way as glass. Since molybdenum and glass change sizes synchronously during heating and cooling, the latter does not crack and therefore the sealing is not broken.

It is known that the intensity of the radiation of a body increases in proportion to the fourth power of the absolute temperature. This follows from the Stefan-Boltzmann law. Consequently, an increase in the temperature of the tungsten filament of a light bulb by only 100° from 24001 to 2500°C leads to an increase in the luminous flux] by 16%. In addition, with an increase in temperature, the proportion of visible light in the total radiation flux increases. This phenomenon is reflected by Wien's law, i.e. as the temperature of the filament increases, the light output increases, which means that the efficiency of the light bulb increases. The increase in temperature is prevented by heating the glass container and evaporating the filament. It is possible to reduce the heating of the cylinder by creating a vacuum in it. These "by reducing the thermal conductivity from the filament to the glass. However, in a vacuum, the evaporation of the filament will increase. This will lead to its thinning and, in the end, the thread will burn out. Filling the balloon with an inert gas, such as nitrogen, prevents the filament from evaporating, and the more the molecules of the filling gas are heavier. The tungsten atoms detached from the filament will hit the gas molecules, their path to the balloon walls will be lengthened, and some atoms may return to the filament. The heavier the fill gas molecules, the more they will prevent the filament from evaporating. Thus, the partial replacement of nitrogen with argon makes it possible to increase the temperature of the tungsten filament to 2600–2700°C. It is impossible to completely replace nitrogen with argon, since the latter has a relatively high electrical conductivity and there will be a danger of an electric arc between the molybdenum holders. The heavier noble gases - krypton and xenon - protect the tungsten filament from destruction even better. They allow you to raise the temperature of the thread to 2800 ° C and reduce the volume of the gas cylinder. Filling them with lamps instead of argon allows you to get 15% more light output, double the life of the filament and reduce the volume of the cylinder by 50%.

To increase the life of electric incandescent lamps, a small amount of iodine is added to the cylinder. He plays the role of a dog guarding a flock of sheep. In a zone with a temperature of approximately 1600 ° C, iodine interacts with tungsten atoms detached from the filament, converting them into a compound Wl 2. During chaotic motion, sooner or later the tungsten (II) iodide molecule enters the region of higher temperatures, where it dissociates in accordance with the equation

W.I.2 → W+2 l

Thus, iodine returns the tungsten atoms to the zone surrounding the filament and, therefore, prevents its evaporation. In iodine lamps, there are no traces of a dark coating of metallic tungsten on the walls of a glass container. For this reason, the light output of such lamps does not decrease over time, and the service life increases.

Chemical elements in the human body

All living organisms on Earth, including humans, are in close contact with environment. Food and drinking water contribute to the intake of almost all chemical elements into the body. They are daily introduced into the body and excreted from it. Analyzes have shown that the amount of individual chemical elements and their ratio in a healthy body of different people are approximately the same.

The opinion that almost all elements of the periodic system of D. I. Mendeleev can be found in the human body is becoming familiar. However, scientists' assumptions go further - not only all chemical elements are present in a living organism, but each of them performs some biological function. It is possible that this hypothesis will not be confirmed. However, as research in this direction develops, the biological role of an increasing number of chemical elements is revealed. Undoubtedly, the time and work of scientists will shed light on this issue.

Bioactivity of individual chemical elements. It has been experimentally established that metals make up about 3% (by mass) in the human body. This is a lot. If we take the mass of a person as 70 kg, then the share of metals is 2.1 kg. For individual metals, the mass is distributed as follows: calcium (1700 g), potassium (250 g.), Sodium (70 g.), Magnesium (42 g.), Iron (5 g.), Zinc (3 g.). The rest is trace elements. If the concentration of an element in the body exceeds 102%, then it is considered a macronutrient. Trace elements are found in the body in concentrations of 10 3 -10 5 %. If the concentration of an element is below 105%, then it is considered an ultramicroelement. Inorganic substances in a living organism are in various forms. Most metal ions form compounds with biological objects. It has already been established today that many enzymes (biological catalysts) contain metal ions. For example, manganese is part of 12 different enzymes, iron - 70, copper - 30, and zinc - more than 100. Naturally, the lack of these elements should affect the content of the corresponding enzymes, and hence the normal functioning of the body. Thus, metal salts are absolutely necessary for the normal functioning of living organisms. This was also confirmed by experiments on a salt-free diet, which was used to feed experimental animals. For this purpose, salts were removed from the food by repeated washing with water. It turned out that eating such food led to the death of animals

Six elements, the atoms of which are part of proteins and nucleic acids: carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur. Next, twelve elements should be distinguished, the role and significance of which for the life of organisms are known: chlorine, iodine, sodium, potassium, magnesium, calcium, manganese, iron, cobalt, copper, zinc, molybdenum. In the literature there are indications of the manifestation of biological activity by vanadium, chromium, nickel and cadmium

There are a large number of elements that are poisonous to a living organism, such as mercury, thallium, pigs, etc. They have an adverse biological effect, but the body can function without them. There is an opinion that the reason for the action of these poisons is associated with the blocking of certain groups in protein molecules or with the displacement of copper and zinc from certain enzymes. There are elements that are poisonous in relatively large quantities, and in low concentrations have a beneficial effect on the body. For example, arsenic is a strong poison that disrupts the cardiovascular system and affects the liver and kidneys, but in small doses it is prescribed by doctors to improve a person's appetite. Scientists believe that microdoses of arsenic increase the body's resistance to the action of harmful microbes. Mustard gas is a well-known poisonous substance. S(CH 2 CH 2 C1) 2. However, in vaseline diluted 20,000 times under the name "Psoriasin" it is used against scaly lichen. Modern pharmacotherapy still cannot do without a significant number of drugs, which include toxic metals. How can one not recall the saying here that in small quantities it heals, but in large quantities it cripples.

Interestingly, sodium chloride (table salt) in a tenfold excess in the body compared to the normal content is a poison. Oxygen, necessary for man for breathing, in high concentration and especially under pressure, it has a toxic effect. From these examples it can be seen that the concentration of an element in the body sometimes plays a very significant, and sometimes catastrophic value.

Iron is a part of blood hemoglobin, or rather, red blood pigments that reversibly bind molecular oxygen. In an adult, the blood contains about 2.6 g of iron. In the process of life in the body there is a constant decay and synthesis of hemoglobin. To restore iron lost with the breakdown of hemoglobin, a person needs a daily intake of about 25 mg. Lack of iron in the body leads to a disease - anemia. However, excess iron in the body is also harmful. It is associated with siderosis of the eyes and lungs - a disease caused by the deposition of iron compounds in the tissues of these organs. A lack of copper in the body causes destruction of blood vessels. In addition, it is believed that its deficiency causes cancer. In some cases, lung cancer in older people is associated with an age-related decrease in copper in the body. However, an excess of copper leads to mental disorders and paralysis of some organs (Wilson's disease). For humans, only large amounts of copper compounds cause harm. In small doses, they are used in medicine as an astringent and bacteriostatic (inhibiting the growth and reproduction of bacteria) agent. For example, copper sulfate (II) CuSO4 used in the treatment of conjunctivitis in the form of eye drops (0.25% solution), as well as for cauterization in trachoma in the form of eye pencils (an alloy of copper (II) sulfate, potassium nitrate, alum and camphor). In case of skin burns with phosphorus, it is abundantly moistened with a 5% solution of copper (II) sulfate.

The bactericidal (causing the death of various bacteria) property of silver and its salts has long been noticed. For example, in medicine, a solution of colloidal silver (collargol) is used to wash purulent wounds, the bladder in chronic cystitis and urethritis, as well as in the form of eye drops for purulent conjunctivitis and blennorrhea. Silver nitrate AgNO3 in the form of pencils, it is used to cauterize warts, granulations, etc. In dilute solutions (0.1-0.25%), it is used as an astringent and antimicrobial agent for lotions, as well as eye drops. Scientists believe that the cauterizing effect of silver nitrate is associated with its interaction with tissue proteins, which leads to the formation of silver protein salts - albuminates.

At present, undoubtedly, it has been established that the phenomenon of ionic asymmetry is inherent in all living organisms - an uneven distribution of ions inside and outside the cell. For example, inside the cells of muscle fibers, heart, liver, kidneys, there is an increased content of potassium ions compared to extracellular. The concentration of sodium ions, on the contrary, is higher outside the cell than inside it. The presence of a concentration gradient of potassium and sodium is an experimentally established fact. Researchers are concerned about the mystery of the nature of the potassium-sodium pump and its functioning. The efforts of many teams of scientists, both in our country and abroad, are aimed at resolving this issue. Interestingly, as the organism ages, the concentration gradient of potassium and sodium ions at the cell boundary decreases. When death occurs, the concentration of potassium and sodium inside and outside the cell immediately equalizes.

The biological function of lithium and rubidium ions in a healthy body is not yet clear. However, there is evidence that by introducing them into the body it is possible to treat one of the forms of manic-depressive psychosis.

Biologists and physicians are well aware that glycosides play an important role in the human body. Some natural glycosides (extracted from plants) actively act on the heart muscle, enhancing contractile functions and slowing the heart rate. If a large amount of cardiac glycoside enters the body, a complete cardiac arrest can occur. Ions of some metals affect the action of glycosides. For example, when magnesium ions are introduced into the blood, the effect of glycosides on the heart muscle is weakened. Calcium ions, on the contrary, enhance the effect of cardiac glycosides.

Some mercury compounds are also extremely toxic. It is known that mercury (II) ions are able to bind strongly with proteins. Toxic effect of mercury (II) chloride HgCl 2(mercuric chloride) manifests itself primarily in necrosis (necrosis) of the kidneys and intestinal mucosa. As a result of mercury poisoning, the kidneys lose their ability to excrete waste products from the blood.

Interestingly, mercury(I) chloride Hg 2 Cl2(the ancient name of calomel) is harmless to the human body. This is probably due to the extremely low solubility of salt, as a result of which mercury ions do not enter the body in noticeable quantities.

Potassium cyanide (Potassium cyanide) KCN- hydrocyanic acid salt HCN. Both connections are fast acting and strong poisons

In acute poisoning with hydrocyanic acid and its salts, consciousness is lost, respiratory and heart paralysis occurs. At the initial stage of poisoning, a person experiences dizziness, a feeling of pressure in the forehead, an acute headache, rapid breathing, and palpitations. First aid for poisoning with hydrocyanic acid and its salts - fresh air, oxygen breathing, warmth. Antidotes are sodium nitrite NaNO 2 and organic nitro compounds: amyl nitrite C5 H11 ONO and propyl nitrite C3 H7 ONO. It is believed that the action of sodium nitrite is reduced to the conversion of hemoglobin to meta-hemoglobin. The latter firmly binds cyanide ions to cyanmethemoglobin. In this way, respiratory enzymes are released from cyanide ions, which leads to the restoration of the respiratory function of cells and tissues.

Sulfur-containing compounds are widely used as antidotes for hydrocyanic acid: colloidal sulfur, sodium thiosulfate Na 2 S2 O 3, sodium tetrathionate Na 2 S4 O 6, as well as sulfur-containing organic compounds, in particular, amino acids - glutathione, cysteine, cystine. Hydrocyanic acid and its salts, when interacting with sulfur, are converted into thiocyanates in accordance with the equation

HCN+ S→HNCS

Thiocyanates are completely harmless to the human body.

For a long time, in case of danger of cyanide poisoning, it was recommended to hold a piece of sugar behind the cheek. In 1915 German chemists Rupp and Golze showed that glucose reacts with hydrocyanic acid and some cyanides to form the non-toxic compound glucose cyanohydrin:

OH OH OH OH N OH OH OH

| | | | | | | | | | | |

CH 2 -CH-CH-CH-CH-C \u003d O + HCN → CH 2 -CH-CH-CH-CH-C-OH

glucose cyanohydrin glucose

Lead and its compounds are quite strong poisons. In the human body, lead accumulates in the bones, liver, and kidneys.

Compounds of the chemical element thallium, which are considered rare, are very toxic.

It should be pointed out that all non-ferrous and especially heavy (located at the end of the periodic table) metals are poisonous in quantities above the permissible ones.

Carbon dioxide is found in large quantities in the human body and therefore cannot be poisonous. For 1 hour, an adult exhales about 20 liters (about 40 g) of this gas. During physical work, the amount of exhaled carbon dioxide increases to 35 liters. It is formed as a result of the combustion of carbohydrates and fats in the body. However, with a high content CO 2 suffocation occurs in the air due to lack of oxygen. The maximum duration of a person's stay in a room with concentration CO 2 up to 20% (by volume) should not exceed 2 hours. In Italy, there is a well-known cave ("Dog's Cave"), in which a person can stand for a long time, and a dog that runs there suffocates and dies. The fact is that approximately to the waist of a person, the cave is filled with heavy (compared to nitrogen and oxygen) carbon dioxide. Since the human head is in the air layer, he does not feel any discomfort. The dog, as it grows, finds itself in an atmosphere of carbon dioxide and therefore suffocates.

Doctors and biologists have found that when carbohydrates are oxidized in the body to water and carbon dioxide, one molecule of oxygen is released per molecule of oxygen consumed. CO 2. Thus, the ratio of the allocated CO 2 to the absorbed About 2(value respiratory coefficient) is equal to one. In the case of fat oxidation, the respiratory coefficient is approximately 0.7. Therefore, by determining the value of the respiratory coefficient, one can judge which substances are predominantly burned in the body. It has been experimentally established that during short-term, but intense muscle loads, energy is obtained due to the oxidation of carbohydrates, and during long-term - mainly due to the combustion of fats. It is believed that the body's switch to fat oxidation is associated with the depletion of the carbohydrate reserve, which is usually observed 5-20 minutes after the start of intense muscular work.

Antidotes.

Antidotes - substances that eliminate the effects of poisons on biological structures and incapacitate poisons through chemical

yellow blood salt K4[ Fe( CN) 6 ] forms poorly soluble compounds with ions of many heavy metals. This property is used in practice for the treatment of poisoning with salts of heavy metals.

A good antidote for poisoning with compounds of arsenic, mercury, lead, cadmium, nickel, chromium, cobalt and other metals is unitiol:

CH 2 -CH- CH 2 SO 3 Na ∙ H 2 O

SH SH

Milk is the universal antidote.

References

1. Brief chemical encyclopedia. – M.: Soviet Encyclopedia, 1961 - 1967. T. I-V.

2. Soviet encyclopedic dictionary. - M:: Sov. encyclopedia, 1983.

4. Andreev I.N. Corrosion of metals and their protection. - Kazan: Tatar book publishing house, 1979.

5. Betekhtin A.G. Mineralogy. - M .: State. Publishing House of Geological Literature, 1950.

6. Butt Yu.M., Duderov G.N., Matveev M.A. General technology of silicates. – M.: Gosstroyizdat, 1962.

7. Bystry G.P. Match production technology. – M.–L.: Goslesbumizdat, 1961.

8. Witt N. Guide to candle production. - St. Petersburg: Printing house of the Department of Foreign Trade, 1851.

9. Voitovich V.A., Mokeeva L.N. biological corrosion. - M .: Knowledge, 1980. No. 10.

10. Voitsekhovskaya A.L., Wolfenzon I.I. Cosmetics today. – M.: Chemistry, 1988.

11. Duderov I.G., Matveeva G.M.,. Sukhanova V.B. General technology of silicates. – M.: Stroyizdat, 1987.

12. Kozlovsky A.L. Adhesives and gluing. – M.: Knowledge, 1976.

13. Kozmal F. Paper production in theory and practice. – M.: Timber industry, 1964.

14. Kukushkin Yu.N. Compounds of the highest order. - L .: Chemistry, 1991.

15. Kulsky L.A., Dal V.V. The problem of clean water. - Kyiv: Naukova Dumka, 1974.

16. Lepeshkov I.N., Rosen B.Ya. Mineral gifts of the sea. – M.: Nauka, 1972.

17. Losev K.S. Water, - L .: Gidrometeoizdat, 1989.

18. Lukyanov P.M. Short story chemical industry of the USSR. - M.: Publishing House of the Academy of Sciences of the USSR, 1959.

19. Lyalko V.I. forever living water. - Kyiv: Science Duma, 1972.

20. Petersburg A.V. Agrochemistry and fertilizer system. – M.: Kolos, 1967.

21. Tedder J., Nehvatal A., Jubb A. Industrial organic chemistry. - M.: Mir, 1977.

22. Ulig G.G., Revi R.U. Corrosion and its control. - L .: Chemistry, 1989.

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24. Chashchin A.M. Chemistry of green gold. - M.: Timber industry, 1987.

25. Engelhardt G., Granich K., Ritter K. Paper sizing. – M.: Timber industry, 1975.

Introduction. 2

Paper and pencils. eleven

Glass. thirteen

Soaps and detergents. 17

Chemical means of hygiene and cosmetics. 20

Chemistry in agriculture. 24

Candle and light bulb. 26

Chemical elements in the human body. 29

References. 33

Introduction

Everywhere, wherever you look, we are surrounded by objects and products made from substances and materials that are obtained in chemical plants and factories. In addition, in everyday life, without knowing it, each person carries out chemical reactions. For example, washing with soap, washing with detergents, etc. When a piece of lemon is lowered into a glass of hot tea, the color fades - tea here acts as an acid indicator, similar to litmus. A similar acid-base interaction occurs when wetting chopped blue cabbage with vinegar. Mistresses know that cabbage turns pink at the same time. Lighting a match, kneading sand and cement with water, or extinguishing lime with water, firing bricks, we carry out real, and sometimes quite complex chemical reactions. The explanation of these and other chemical processes that are widespread in human life is the lot of specialists.

Cooking is also a chemical process. No wonder they say that women chemists are often very good cooks. Indeed, cooking in the kitchen is sometimes like doing organic synthesis in a lab. Only instead of flasks and retorts in the kitchen they use pots and pans, but sometimes autoclaves in the form of pressure cookers. It is not necessary to list further the chemical processes that a person conducts in everyday life. It should only be noted that in any living organism various chemical reactions are carried out in huge quantities. The processes of digestion of food, respiration of animals and humans are based on chemical reactions. The growth of a small blade of grass and a mighty tree is also based on chemical reactions.

Chemistry is a science, an important part of natural science. Strictly speaking, science cannot surround man. It may be surrounded by the results of the practical application of science. This clarification is very significant. At present, one can often hear the words: “chemistry has spoiled nature”, “chemistry has polluted the reservoir and made it unsuitable for use”, etc. In fact, the science of chemistry has nothing to do with it. People, using the results of science, poorly formalized them into a technological process, irresponsibly reacted to the requirements of safety rules and environmentally acceptable standards for industrial discharges, ineptly and excessively used fertilizers on agricultural land and plant protection products from weeds and plant pests. Any science, especially natural science, cannot be good or bad. Science is the accumulation and systematization of knowledge. Another thing is how and for what purposes this knowledge is used. However, this already depends on the culture, qualifications, moral responsibility and morality of people who do not extract, but use knowledge.

Modern man cannot do without products of the chemical industry, just as it is impossible to do without electricity. The same situation is with the products of the chemical industry. It is necessary to protest not against certain chemical industries, but against their low culture.

Human culture is a complex and diverse concept, in which such categories arise as the ability of a person to behave in society, to speak his native language correctly, to keep his clothes and appearance neat, etc. However, we often talk and hear about the culture of construction, the culture of production, the culture of agriculture, etc. Indeed, when it comes to the culture of Ancient Greece or even earlier civilizations, they first of all remember the crafts that people of that era owned, what tools they used, what they knew how to build, how They knew how to decorate buildings and individual objects.

Many important chemical processes for humans were discovered long before chemistry took shape as a science. A significant number of chemical discoveries have been made by observant and inquisitive artisans. These discoveries turned into family or clan secrets, and not all of them have come down to us. Some of them were lost to mankind. It was and is necessary to spend a lot of work, create laboratories, and sometimes institutes for revealing the secrets of the ancient masters and their scientific interpretation.

Many do not know how the TV works, but they successfully use it. However, knowing the device of the TV will never interfere with anyone in its proper operation. So it is with chemistry. Understanding the essence of chemical processes that we encounter in everyday life can only benefit a person.

Water

Water on a planetary scale. Mankind has long paid great attention to water, because it was well known that where there is no water, there is no life. In dry soil, grain can lie for many years and germinate only in the presence of moisture. Despite the fact that water is the most common substance, it is distributed very unevenly on Earth. On the African continent and in Asia there are vast expanses devoid of water - deserts. A whole country - Algeria - lives on imported water. Water is delivered by ship to some coastal areas and to the islands of Greece. Sometimes there water costs more than wine. According to the United Nations, in 1985, 2.5 billion of the world's population lacked clean drinking water.

The surface of the globe is 3/4 covered with water - these are oceans, seas; lakes, glaciers. In fairly large quantities, water is found in the atmosphere, as well as in the earth's crust. The total reserves of free water on Earth are 1.4 billion km 3 . The main amount of water is contained in the oceans (about 97.6%), in the form of ice on our planet there is 2.14 %. The water of rivers and lakes is only 0.29 % and atmospheric water - 0.0005 %.

Thus, water is on Earth in constant motion. The average time of its stay in the atmosphere is estimated at 10 days, although it varies with the latitude of the area. For the polar latitudes, it can reach 15, and in the middle - 7 days. The change of water in the rivers occurs on average 30 times a year, that is, every 12 days. The moisture contained in the soil is renewed in 1 year. The waters of flowing lakes are exchanged for decades, and stagnant lakes for 200-300 years. The waters of the World Ocean are renewed on average for 3000 years. From these figures, you can get an idea of ​​how much time is needed for self-cleaning of reservoirs. You just need to keep in mind that if a river flows out of a polluted lake, then the time of its self-cleaning is determined by the time of self-cleaning of the lake.

Water in the human body. It is not very easy to imagine that a person is approximately 65% ​​water. With age, the water content in the human body decreases. The embryo consists of 97% water, the body of a newborn contains 75%, and in an adult - about 60 %.

In a healthy body of an adult, a state of water balance or water balance is observed. It lies in the fact that the amount of water consumed by a person is equal to the amount of water excreted from the body. Water metabolism is an important part of the overall metabolism of living organisms, including humans. Water metabolism includes the processes of absorption of water that enters the stomach when drinking and with food, its distribution in the body, excretion through the kidneys, urinary tract, lungs, skin and intestines. It should be noted that water is also formed in the body due to the oxidation of fats, carbohydrates and proteins taken with food. Such water is called metabolic. The word metabolism comes from the Greek, which means change, transformation. In medicine and biological science, metabolism refers to the processes of transformation of substances and energy that underlie the life of organisms. Proteins, fats and carbohydrates are oxidized in the body to form water. H 2 O and carbon dioxide (carbon dioxide) CO 2. When 100 g of fats are oxidized, 107 g of water is formed, and when 100 g of carbohydrates are oxidized, 55.5 g of water is formed. Some organisms manage only with metabolic water and do not consume it from the outside. An example is carpet moth. Do not need water in natural conditions jerboas that are found in Europe and Asia, and the American kangaroo rat. Many people know that in an extremely hot and dry climate, a camel has a phenomenal ability to go without food and water for a long time. For example, with a mass of 450 kg for an eight-day journey through the desert, a camel can lose 100 kg in mass, a then restore them without consequences for the body. It has been established that his body uses the water contained in the fluids of tissues and ligaments, and not blood, as happens with a person. In addition, camel humps contain fat, which serves as both a food store and a source of metabolic water.

The total volume of water consumed by a person per day when drinking and with food is 2-2.5 liters. Due to the water balance, the same amount of water is excreted from the body. Through the kidneys and urinary tract, about 50-60 % water. When the human body loses 6-8 % moisture in excess of the usual norm, the body temperature rises, the skin turns red, the heartbeat and breathing become more frequent, muscle weakness and dizziness appear, and a headache begins. A loss of 10% of water can lead to irreversible changes in the body, and a loss of 15-20% leads to death, because the blood thickens so much that the heart cannot cope with its pumping. The heart has to pump about 10,000 liters of blood per day. A person can live without food for about a month, and without water - only a few days. The body's response to lack of water is thirst. In this case, the feeling of thirst is explained by irritation of the mucous membrane of the mouth and pharynx due to a large decrease in humidity. There is another point of view on the mechanism of formation of this feeling. In accordance with it, a signal about a decrease in the concentration of water in the blood is sent to the cells of the cerebral cortex by nerve centers embedded in the blood vessels.

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Attention! The slide preview is for informational purposes only and may not represent the full extent of the presentation. If you are interested in this work, please download the full version.

Target: to show the close connection of chemistry with our daily life.

Equipment: multimedia projector; three types of soap - household, toilet, liquid; two types of washing powder - for cotton and woolen fabrics; phenolphthalein; soda; acetic acid solution; citric acid crystalline; flour; water; test tubes; chemical glasses; putty knife.

PROGRESS OF THE EVENT

(Slide 2)

Teacher. In the beginning was the word. And the word was God. For seven days and nights, the creator created the material world, which consists of matter. And the substance is the object of study of the science of CHEMISTRY.

(Slide 3)

– So, let's be fascinated by this divine science together, and make sure that our entire environment is chemicals. And you and I, our body and even our feelings are also chemistry.
Let's start from the very beginning. Here the baby is born. (Slide 4) With his first cry, the lungs expand, the baby takes its first breath. And this process accompanies us all our lives.

Questions to the audience:

What kind of gas do we need? (Oxygen)

What is the name of the substance that carries oxygen? (Hemoglobin)

Let's admire this wonderful molecule together. (Slide 5) Oxygen, having joined, to the iron ion located in the middle of hemoglobin, as in a carriage, travels to all organs of our body. Our tissues are filled with life-giving oxygen, thanks to which oxidation processes take place.

- And now another moment. Tell me, have you experienced stress? Certainly! I believe stress is familiar to many.

Question to the audience:

– Do you know what hormone is produced in this case? (Adrenalin)

- Did you feel nervous today?

- Of course, at school you can’t do without excitement! And again you have an adrenaline rush. (Slide 6) Wise nature created adrenaline for action. Therefore, when adrenaline is released, a person needs to actively move, run, jump, wave his arms. What are we going to do now. We got up. We raised our hands, we actively shake our hands. Let's stomp our feet at the same time.

- Well done! All accumulated adrenaline worked out.

– It turns out that resistance to stress depends on the protein to which adrenaline is attached. If the protein molecule is large, the person is resistant to stress; if it is small, the resistance to stress is low. Let's admire the wonderful structure of the protein molecule. (Slide 7) Let us admire the wise nature that created such beauty.

Question to the audience:

What determines the structure of a protein? Where is hereditary information encrypted? (DNA)

– Of course, in the DNA molecule. Let's look at the structure of DNA. (Slide 8) Look what a beauty! On the left is a top view, on the right is a double helix consisting of two complementary strands. No wonder they are so named, one chain compliments the other. The full name of DNA is deoxyribonucleic acid. Sounds like a song!

Let's do a thought experiment - let's go to our house. We are always welcome at home.

Question to the audience:

- Who meets you first at the door? What are your feelings about this?

- Amazing! All of us are waiting at home for moms and dads, grandparents, cats and dogs, hamsters and parrots. And we are happy to meet them. (Slide 9)

- Now imagine - in front of you is a plate of dumplings seasoned with sour cream. Or a pie with a ruddy crust is smoking on the table. The house is filled with amazing aroma. You bring the desired piece to your mouth. What do you experience?
You would not have experienced all this bliss if the hormone of joy, serotonin, had not been formed in the body. Admire the hero of the occasion! (Slide 10) Good! Let's work it out here and now. No, unfortunately you won't be holding a hefty piece of cake in your hand right now. You don't pet your beloved pet. We will do it easier - remember childhood. Each of us, as a child, smiled and laughed fervently about 360 times a day. Smile, find bumps of joy on your face next to your cheekbones. Rub them vigorously with your fingertips. Look at your neighbors on the left and right, give them your smile! This is how serotonin is produced!

So, we are at home. First of all, we will visit the home laboratory called the bathroom. (Slide 11) We wash our hands, at the same time without wasting time, turn on the washing machine. What soap to choose? What kind of powder? Five chemists are needed to conduct the experiment. With them, we will check the alkaline properties of three types of soap - laundry, toilet, liquid and two types of powder - for wool and for cotton fabrics. (There are samples of the above detergents in five test tubes. A few milliliters of water are poured into each, shaken. Then a drop of phenolphthalein solution is dropped into the solutions, the intensity of crimson staining is observed and conclusions are drawn.)

Findings. Most bright coloring in a solution of laundry soap, the medium is strongly alkaline, therefore, this soap must be used for washing heavily soiled products. The toilet soap solution also changed the color of the indicator - we use it to wash dirty hands and body. But liquid soap can be used often, since its solution did not change the color of the indicator, the medium is neutral.
The most alkaline environment in a solution of laundry detergent for cotton fabrics, therefore, this type of detergent should be used to wash items made from fabrics that can withstand an aggressive environment. In another form of powder, the solution of phenolphthalein only turned pink, that is, it is suitable for washing products made from natural silk and woolen fabrics.

- We pass to the kitchen - the main home laboratory. Here the main sacraments of preparation take place. What is the main laboratory of the house equipped with? (Slide 12)
Meet "Hot Majesty" - a stove.

Questions to the audience:

- What is the plate for? What is burning in it?

- And now, please, someone who wishes to write down the reaction of methane combustion on the board, and compare it with the recording on the screen.

- Let's draw conclusions. Methane reacts with oxygen to release carbon dioxide and water vapor. Therefore, when igniting the burners, it is necessary to open the window. And why are we starting a combustion reaction? Of course, we need the energy released as a result of the reaction. Therefore, the reaction is written in thermochemical form, at the end of the equation +Q, which means the release of heat - the reaction is exothermic.

- Next in line is Frosty Majesty - a refrigerator.

Question to the audience:

What is a refrigerator for?

- You are right, it is necessary to slow down the processes of food spoilage - the reactions of oxidation and decomposition. The refrigerator personifies the most difficult section of chemistry - chemical kinetics. Let's treat the "Frosty Majesty" with respect.

- Let's move on to the "Highnesses" - cabinets. What is not here - spoons, ladles, pots, pans, cereals, flour, salt, sugar, spices and much more tasty and interesting. We will cook a pie from shortcrust pastry, and chemically competently. In cookbooks, it is recommended to add soda quenched with vinegar to prepare the dough.

Question to the audience:

- What is the purpose of adding soda with vinegar to the dough?

- It is true that the cake was magnificent. Now look at this reaction. (Demonstration of the interaction of soda with acetic acid). We observe "boiling" due to the release of carbon dioxide. So, the bulk of carbon dioxide has escaped into the atmosphere, there is not much gas left to raise the test. Therefore, we do not extinguish soda with vinegar, but add soda and dry crystalline citric acid to the flour. Knead the dough by adding the necessary ingredients.

(Demonstration. In a deep glass, mix soda, crystalline citric acid, flour, add water. A slow rise of lush dough is observed. In another glass, mix flour with water, add soda quenched with vinegar there. In this case, the dough rises much less and quickly settles. )

– You and I made sure that pies also need to be prepared chemically competently. Carbon dioxide must be released during the baking process - the result is a fluffy cake, just like ours! (Slide 13)

“I think I convinced you that chemistry is the poem of matter!” (Slide 14)

Chekalina Olesya

This work is addressed to those who are just beginning to get acquainted with interesting world chemistry. The work is made in the form of a computer presentation, it is recommended to show it to students who have just started studying chemistry or are already studying this subject. It gives an idea of ​​the chemicals that surround us in everyday life, in our daily life. The work expands the understanding of the use of various (synthetic or natural) substances, increases the importance of the science of chemistry. The presentation is recommended to be shown in the classroom, in elective courses, circles and electives in chemistry.

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Substances around us. Completed by Chekalina Olesya Teacher: Karmaza Elena Vladimirovna Ivangorodskaya high school №1

We deal with different types every day. household chemicals, ranging from ordinary soap and ending with dyes for cars, as well as dozens of types, hundreds of chemical industry products designed to perform all possible household chores. Chemistry in the kitchen; Chemistry in the bathroom; Chemistry in the garden and garden; Chemistry in cosmetics and hygiene; Chemistry in the home first aid kit. Here are some of them:

Chemistry in the kitchen Chemistry in the kitchen is necessary, first of all, for human health. We spend half our lives in the kitchen. In the kitchen, everything must be kept clean and tidy, because in unsanitary conditions, you can get skin diseases and even lead to poisoning. In order for the kitchen not to be a vulnerable place for human health, it is necessary to constantly put things in order on it: · The kitchen table must be wiped before and after each meal; It is best to wipe the surface of the table with a cloth pre-dipped in soapy water with the addition of acetic acid (this is very effective method) ; · For washing dishes, liquid SMPs (dishwashing detergents such as AOS, Sorti, etc.) with high soapiness are most effective; · Cleaning of glass surfaces is carried out by means of spray-like substances.

Chemistry in the bathroom Chemistry in the bathroom also means cleanliness. in the bath we induce body hygiene. In order to clean the bathroom, it is necessary to use chlorine-containing substances, cleaning powders (“Pemo-lux”, “Soda effect”, etc.). In order to restore body hygiene, a person uses many chemicals - these are all kinds of shampoos, shower gels, soaps, body creams, all kinds of lotions, etc.

Chemistry in the garden Fruits, berries, vegetables, cereals - all this grows in the garden, and in order for the harvest to be good, a person adds various chemicals to accelerate plant growth, pesticides, herbicides. All this harms health to a different extent, primarily to the consumer of these fruit and berry crops. To avoid the harmful effects of these substances, you need to use natural fertilizers of animal origin. Chemistry in the garden is used mainly to protect against pests and plant diseases: fruit crops, berry crops, vegetables, flowers. Mineral fertilizers containing nitrogen, potassium, phosphorus and trace elements are also used. They help increase plant productivity. Insecticides, fungicides, repellents - they mean the fight against harmful insects, garden fungi, etc.

Chemistry in cosmetics and hygiene female half humanity. Hygiene products include soap, shampoos, deodorants, creams. Cosmetic products include lipsticks, powder, eye shadow, mascara and eyebrows, eyeliners, lips, foundation and much more. Nowadays, there is no such cosmetics that would not be of chemical origin, with the exception of creams and masks prepared on the basis of plants. To protect yourself from low-quality cosmetics, you need to monitor their expiration dates. After all, the substances from which they are made are exposed to the environment.

Chemistry in the first-aid kit "There is a potion for every pain" (Russian proverb) In ancient times there were no pharmacies: doctors made up the medicines themselves. They bought raw materials for the manufacture of medicinal potions from "diggers of plant roots" and stored them in a warehouse - a pharmacy. The word "pharmacy" itself comes from the Greek "warehouse". In Russia, under Tsar Mikhail Fedorovich (1613-1645), pharmacies already had the position of "alchemist" (laboratory chemist), who prepared medicines. Many famous scientists who went down in history as chemists, in their main position were pharmacists and pharmacists. It goes without saying that every family should have a first aid kit. And this is the most "chemical" place in the apartment.

Pharmacy old-timers "The older, the more to the right. The younger, the more expensive" (Russian proverb) There are ancient medicines that have not lost their significance so far. This is potassium permanganate - "potassium permanganate", hydrogen peroxide, iodine, ammonia, sodium chloride, Epsom salt (magnesium sulfate), baking soda (sodium bicarbonate), alum, lapis (silver nitrate) "lead sugar" - lead acetate , boric acid, acetylsalicylic acid (aspirin) - a common antipyretic.

Nature heals Nature is an inexhaustible treasury of healing agents that has not yet been fully studied by people. Among them, a place of honor is occupied by: · honey, · propolis, · kombucha They contain natural chemicals.

HONEY "A bird of honey, God's bee, You, the queen of forest flowers! Bring honey, Take it from flower cups, From fragrant blades of grass, So that I can relieve pain, Satisfy my son's suffering ..." (Karelian epic "Kalevala") Bee honey in ointments it helps the formation of glutathione, a substance that plays an important role in the redox processes of the body and accelerates the growth and division of cells. Therefore, under the influence of honey, wounds heal faster. An ointment made from equal amounts of honey and sea buckthorn oil works especially strongly.

Propolis Propolis ("bee glue") is a resinous substance used by bees to seal the cracks in their homes. It is obtained during the primary digestion of pollen by bees and contains about 59% resins and balms, 10% essential oils and 30% wax.

Kombucha "Rising from the silver shackles, a sweet and salty pool will be born, inhabited by an unknown breath and a fresh crowd of bubbles." (B. Akhmadulina) Undeservedly forgotten kombucha helps create a small "factory" of soft drinks right at home, producing tasty and, what is important, healthy products that can quench thirst in the summer heat.

Disease of the 21st century - allergy