It is obtained from table salt. Minerals: Salt

is a white crystalline mineral substance found in nature, soluble in water, one of the few minerals that people eat. Edible salt is 39% sodium and 61% chlorine. Salt is the oldest spice.
Table salt of natural origin almost always has impurities of other mineral salts, which can give it shades of different colors (usually gray).

According to the method of extraction, salt is divided into several types:
- stone. Rock salt lies in layers in the ground and is mined by mining;
- self-planting, or lake. This salt is in the form of layers at the bottom of lakes and is the main source of salt in the CIS;
- garden salt. Sadochnaya salt is obtained by evaporation or freezing from the water of estuaries and lakes;
- boil-out. Evaporated salt is obtained by evaporation from underground brines.

Edible salt is produced:
quality - extra, premium, first and second grades;
according to the granulometric composition - grinding No. 1, 2 and 3.

Edible salt is used in boiler houses for chemical purification of water from heating networks, in food production for the preservation and preservation of all types of animal products (meat, fish, etc.), fruits and vegetables, animal feed, etc., in the production of detergents and for other purposes.
It also serves as a raw material for the production of chlorine, hydrochloric acid, caustic soda, soda, the production of metallic sodium, is used in dyeing, soap making and many other industries.
Significant volumes of rock salt (up to 30-35%) are used in the fight against icing of roads and other roads. On average, more than half of the produced salt is used in the food industry, about 40% - for technical purposes and the rest is the so-called fodder salt.

Physical and chemical characteristics of food salt GOST 13830-97.:

Name of indicator	The norm for the variety
	Extra	Higher	First
Appearance	Crystalline bulk product
Taste	Salty without foreign taste
Color	White
Smell	Missing
physical and chemical indicators
Mass fraction of sodium chloride, %, not less than	99,50 *	98,20 *	97,50 *
Mass fraction of calcium ion, %, no more	0,02 *	0,35 *	0,55 *
Mass fraction of magnesium ion, %, no more	0,01 *	0,08 *	0,10 *
Mass fraction of sulfate ion, %, no more	0,20 *	0,85 *	1,20 *
Mass fraction of potassium ion, %, no more	0,02 *	0,10 *	0,20 *
Mass fraction of iron oxide (III),%, no more	0,005 *	0,040 *	0,040 *
Mass fraction of sodium sulfate, %, no more	0,21 *	Not regulated
Mass fraction of water-insoluble residue (n.o.),%, no more	0,03 *	0,25 *	0,45 *
Mass fraction of moisture, %, no more	0,10	0,70	0,70
solution pH	6,5-8,0	Not regulated
Size: up to 0.5 mm inclusive, %, not less over 0.5 mm up to 1.2 mm, %, no more	95,0 * 5,0 *	95,0 * 5,0 *	95,0 * 5,0 *

Note.
* - in terms of dry matter.
Mass fraction of potassium ferrocyanide for salt with anti-caking additive is not more than 0.001%.
The content of toxic elements and radionuclides is within the existing sanitary standards.

Food salt safety requirements GOST 13830-97.
Edible salt (sodium chloride, sodium chloride) is fire and explosion-proof, non-toxic. When it comes into contact with intact skin, it does not have a harmful effect, however, when it gets on skin wounds, it worsens their healing.

Packing, transportation and storage.
Edible salt is produced in packaged form. Depending on the net weight, the salt is packed in polyethylene or propylene bags (up to 50 kg), soft specialized disposable containers (900-1000 kg).
Packaged edible salt is transported by all means of transport in accordance with the rules for the carriage of goods in force for this type of transport. Vehicles must be covered, clean and dry.
Transportation of edible salt in container shipments is carried out in covered wagons, gondola cars, on specialized railway platforms, ships, as well as by road.
Edible salt is stored in dry warehouses. It is allowed to store the product in containers on hard-surface sites equipped with sheds.
Guaranteed shelf life of salt without additives, packed in packs with an inner bag and in cardboard packs - two and a half years, in packs without an inner bag - one year, in plastic bags - two years, in paper bags with a polyethylene liner, polyethylene and polypropylene woven - two years, in containers of all types with a polyethylene liner - two years, in containers without liner - one year.
Shelf life under controlled temperature and humidity conditions of salt without additives, packed in polyethylene bags, polypropylene bags with polyethylene liners, soft containers with polyethylene liners - five years.

SALT-sodium chloride NaCl. Moderately soluble in water, solubility depends little on temperature: the solubility coefficient of NaCl (in g per 100 g of water) is 35.9 at 20 ° C and 38.1 at 80 ° C. The solubility of sodium chloride is significantly reduced in the presence of hydrogen chloride, sodium hydroxide , salts - metal chlorides. It dissolves in liquid ammonia, enters into exchange reactions. The density of NaCl is 2.165 g / cm 3, the melting point is 800.8 ° C, the boiling point is 1465 ° C.

They used to say: "Salt is the head of everything, without salt and zhito - grass"; “One eye is on the police (where is the bread), the other is on the salt shaker (salt shaker)”, and more: “Without bread it’s not satisfying, without salt it’s not sweet” ... Buryat folk wisdom says: “When you are going to drink tea, put a pinch in it salt; food is digested faster from it, stomach diseases will disappear.

It is unlikely that we will know when our distant ancestors tasted salt for the first time: we are separated from them by ten to fifteen thousand years. At that time there were no dishes for cooking, people soaked all vegetable products in water and baked them on smoldering coals, and meat, planted on sticks, was fried in a fire flame. The “table salt” of primitive people was probably ash, which inevitably fell into food during its preparation. The ash contains potash - potassium carbonate K 2 CO 3 , which in places remote from the seas and salt lakes has long served as a food seasoning.

Perhaps one day, for lack of fresh water, meat or roots and leaves of plants were soaked in salty sea or lake water, and the food turned out to be tastier than usual. Perhaps, in order to protect it from birds of prey and insects, people hid the meat they got for the future in sea water, and then found that it acquired a pleasant taste. Observant hunters of primitive tribes could notice that animals like to lick salt licks - white crystals of rock salt, protruding in some places from the ground, and tried to add salt to food. There could be other cases of the first acquaintance of people with this amazing substance.

Pure table salt, or sodium chloride NaCl, is a colorless, non-hygroscopic (does not absorb moisture from the air) crystalline substance that is soluble in water and melts at 801 ° C. In nature, sodium chloride occurs in the form of a mineral halite- rock salt. The word "halite" comes from the Greek "galos", meaning both "salt" and "sea". The bulk of halite is most often found at a depth of 5 km below the earth's surface. However, the pressure of the layer of rocks located above the salt layer turns it into a viscous, plastic mass. "Floating up" in places of low pressure of the covering rocks, the salt layer forms salt "domes" that go out in a number of places.

Natural halite is rarely pure white. More often it is brownish or yellowish due to impurities of iron compounds. There are, but very rarely, blue halite crystals. This means that for a long time they were in the depths of the earth in the neighborhood of rocks containing uranium, and were exposed to radioactive irradiation.

In the laboratory, blue crystals of sodium chloride can also be obtained. This does not require radiation; just in a tightly closed vessel, you need to heat a mixture of table salt NaCl and a small amount of metallic sodium Na. The metal is able to dissolve in salt. When sodium atoms penetrate into a crystal consisting of Na + cations and Cl - anions, they “complete” the crystal lattice, occupying suitable places and turning into Na + cations. The released electrons are located in those places of the crystal where the chloride anions Cl -? . Such unusual places inside the crystal, occupied by electrons instead of ions, are called "vacancies".

When the crystal is cooled, some vacancies are combined, and this is the reason for the appearance of a blue color. By the way, when a blue crystal of salt is dissolved in water, a colorless solution is formed - just like from ordinary salt.

Greek poet Homer (8th century BC), who wrote Iliad And Odyssey, called table salt "divine". In those days, it was valued more than gold: after all, as the proverb said, “you can live without gold, but you can’t live without salt.” Because of the deposits of rock salt, military clashes took place, and sometimes the lack of salt caused "salt riots".

On the tables of emperors, kings, kings and shahs there were salt shakers made of gold, and they were in charge of a particularly trusted person - a salt shaker. Warriors were often paid salaries in salt, and officials received salt rations. As a rule, salt springs were the property of rulers and crowned persons. In the Bible there is an expression "drinks salt from the king's palace", meaning a person who receives maintenance from the king.

Salt has long been a symbol of purity and friendship. “You are the salt of the earth,” Christ said to his disciples, referring to their high moral qualities. Salt was used during sacrifices, newborn children of the ancient Jews were sprinkled with salt, and in Catholic churches, when baptized, a crystal of salt was placed in the baby's mouth.

In the custom of the Arabs, when approving solemn agreements, they served a vessel with salt, from which, as a sign of proof and guarantee of permanent friendship, the persons who entered into the agreement - the "covenant of salt" - ate several grains of it. “To eat together a pood of salt” - among the Slavs means to get to know each other well and make friends. According to Russian custom, when they bring bread and salt to guests, they wish them good health.

Table salt is not only a food product, but has long been a common preservative; it has been used in the processing of leather and fur raw materials. And in technology, it is still the raw material for the production of almost all sodium compounds, including soda.

Table salt was also part of the most ancient medicines, it was attributed to healing properties, a cleansing and disinfecting effect, and it has long been noticed that table salt from different deposits has different biological properties: the most useful in this respect is sea salt. IN Herbal medicine, published in Russia in the 17th century, it is written: “Two essences of salt, one was dug from a mountain, and the other was found in the sea, and the one from the sea is lutchi, and besides sea salt, that lutchi that is white.”

However, the use of salt must be observed in moderation. It is known that the average European daily absorbs up to 15 g of salt with food, while the average Japanese - about 40 g. Just the Japanese hold the world championship in the number of patients with hypertension - a disease, one of the reasons for which is that in the body retains more fluid than it needs. Cells swell from its excess, compress blood vessels, so blood pressure rises, from which the heart begins to work with overload. It also becomes difficult for the kidneys, which cleanse the body of excess sodium cations.

No plant can grow on soil covered with salt, salt marshes have always been a symbol of the barren and uninhabited land. When the ruler of the Holy Roman Empire, Frederick I Barbarossa, destroyed Milan in Italy in 1155, he ordered that the ruins of the defeated city be sprinkled with salt as a sign of its complete destruction... For different peoples at all times, scattering salt meant bringing trouble and losing health.

In ancient times, people used several methods for extracting table salt: the natural evaporation of sea water in "salt gardens", where sodium chloride NaCl - "sea" salt fell out, the digestion of water from salt lakes to obtain "evaporated" salt, and breaking out "rock" salt in underground mines. All these methods give a salt with impurities of magnesium chloride MgCl 2 6 H 2 O, potassium sulfates K 2 SO 4 and magnesium MgSO 4 7H 2 O and magnesium bromide MgBr 2 6H 2 O, the content of which reaches 8–10%.

In sea water, on average, 1 liter contains up to 30 g of various salts, and table salt accounts for 24 g. The technology for obtaining sodium chloride NaCl from sea and lake water has always been quite primitive.

For example, at the end of the "Bronze Age" - three, three and a half thousand years BC - ancient salt pans doused logs with sea water, and then burned them and chose salt from the ashes. Later, salty waters were boiled on large baking sheets, and animal blood was added to remove impurities, collecting the resulting foam. Around the end of the 16th century salt solutions were purified and concentrated by passing through towers filled with straw and bushes. Evaporation of a salt solution in air was also carried out in a very primitive way, pouring the brine over a wall made of bundles of brushwood and straw.

Salt making, the oldest of the chemical crafts, originated in Russia, apparently at the beginning of the 7th century. Salt mines belonged to the monks, who were favored by the Russian tsars, they were not even taxed on the sold salt. Salt boiling brought huge profits to the monasteries. Pickles were extracted not only from lakes, but also from underground salt springs; boreholes that were built for this, in the 15th century. reached a length of 60–70 m. Pipes made of solid wood were lowered into the wells, and brines were evaporated in iron pans on a wood-burning firebox. In 1780, more than a hundred thousand tons of salt were boiled in this way in Russia ...

Currently, table salt is mined from the deposits of salt lakes and from deposits of rock salt - halite.

Table salt is not only an important food seasoning, but also a chemical raw material: sodium hydroxide, soda, chlorine are obtained from it.

Ludmila Alikberova

Table salt is sodium chloride used as a food additive and food preservative. It is also used in the chemical industry, medicine. It serves as the most important raw material for the production of caustic soda, soda and other substances. The formula for table salt is NaCl.

Formation of an ionic bond between sodium and chlorine

The chemical composition of sodium chloride reflects the conditional formula NaCl, which gives an idea of ​​the equal number of sodium and chlorine atoms. But the substance is formed not by diatomic molecules, but consists of crystals. When an alkali metal interacts with a strong non-metal, each sodium atom gives off more electronegative chlorine. There are sodium cations Na + and anions of the acid residue of hydrochloric acid Cl - . Oppositely charged particles are attracted, forming a substance with an ionic crystal lattice. Small sodium cations are located between large chloride anions. The number of positive particles in the composition of sodium chloride is equal to the number of negative ones, the substance as a whole is neutral.

Chemical formula. Table salt and halite

Salts are complex ionic substances whose names begin with the name of the acid residue. The formula for table salt is NaCl. Geologists call a mineral of this composition “halite”, and sedimentary rock is called “rock salt”. An obsolete chemical term that is often used in industry is "sodium chloride". This substance has been known to people since ancient times, it was once considered "white gold". Modern schoolchildren and students, when reading the equations of reactions involving sodium chloride, call chemical signs ("sodium chloride").

We will carry out simple calculations according to the formula of the substance:

1) Mr (NaCl) \u003d Ar (Na) + Ar (Cl) \u003d 22.99 + 35.45 \u003d 58.44.

The relative is 58.44 (in amu).

2) The molar mass is numerically equal to the molecular weight, but this value has units of g / mol: M (NaCl) \u003d 58.44 g / mol.

3) A 100 g sample of salt contains 60.663 g of chlorine atoms and 39.337 g of sodium.

Physical properties of table salt

Brittle crystals of halite are colorless or white. In nature, there are also deposits of rock salt, painted in gray, yellow or blue. Sometimes the mineral substance has a red tint, which is due to the types and amount of impurities. The hardness of halite is only 2-2.5, the glass leaves a line on its surface.

Other physical parameters of sodium chloride:

• smell - absent;
• taste - salty;
• density - 2.165 g / cm3 (20 ° C);
• melting point - 801 ° C;
• boiling point - 1413 ° C;
• solubility in water - 359 g / l (25 ° C);

Obtaining sodium chloride in the laboratory

When metallic sodium interacts with gaseous chlorine in a test tube, a white substance is formed - sodium chloride NaCl (common salt formula).

Chemistry gives an idea of ​​the different ways to obtain the same compound. Here are some examples:

NaOH (aq.) + HCl \u003d NaCl + H 2 O.

Redox reaction between metal and acid:

2Na + 2HCl \u003d 2NaCl + H 2.

Action of acid on metal oxide: Na 2 O + 2HCl (aq.) = 2NaCl + H 2 O

Displacement of a weak acid from a solution of its salt by a stronger one:

Na 2 CO 3 + 2HCl (aq.) \u003d 2NaCl + H 2 O + CO 2 (gas).

All of these methods are too expensive and complicated to be applied on an industrial scale.

Salt production

Even at the dawn of civilization, people knew that after salting, meat and fish last longer. Transparent, regular-shaped halite crystals were used in some ancient countries instead of money and were worth their weight in gold. The search and development of halite deposits made it possible to meet the growing needs of the population and industry. The most important natural sources of table salt:

• deposits of the mineral halite in different countries;
• water of the seas, oceans and salt lakes;
• layers and crusts of rock salt on the banks of salt water bodies;
• halite crystals on the walls of volcanic craters;
• salt marshes.

In industry, four main methods of obtaining table salt are used:

• leaching of halite from the underground layer, evaporation of the resulting brine;
• mining in ;
• evaporation or brine of salt lakes (77% of the mass of dry residue is sodium chloride);
• use of a by-product of desalination of salt water.

Chemical properties of sodium chloride

In its composition, NaCl is a medium salt formed by an alkali and a soluble acid. Sodium chloride is a strong electrolyte. The attraction between ions is so strong that only highly polar solvents can destroy it. In water, substances decompose, cations and anions (Na +, Cl -) are released. Their presence is due to the electrical conductivity, which has a solution of common salt. The formula in this case is written in the same way as for dry matter - NaCl. One of the qualitative reactions to the sodium cation is the yellow coloring of the burner flame. To obtain the result of the experiment, you need to collect a little solid salt on a clean wire loop and add it to the middle part of the flame. The properties of table salt are also associated with the feature of the anion, which consists in a qualitative reaction to the chloride ion. When interacting with silver nitrate in solution, a white precipitate of silver chloride precipitates (photo). Hydrogen chloride is displaced from the salt by stronger acids than hydrochloric: 2NaCl + H 2 SO 4 = Na 2 SO 4 + 2HCl. Under normal conditions, sodium chloride does not undergo hydrolysis.

Areas of application of rock salt

Sodium chloride lowers the melting point of ice, which is why a mixture of salt and sand is used on roads and sidewalks in winter. It absorbs a large amount of impurities, while thawing pollutes rivers and streams. Road salt also accelerates the corrosion process of car bodies and damages trees planted next to roads. In the chemical industry, sodium chloride is used as a raw material for the production of a large group of chemicals:

• of hydrochloric acid;
• metallic sodium;
• gaseous chlorine;
• caustic soda and other compounds.

In addition, table salt is used in the manufacture of soaps and dyes. As a food antiseptic, it is used in canning, pickling mushrooms, fish and vegetables. To combat thyroid disorders in the population, the table salt formula is enriched by adding safe iodine compounds, for example, KIO 3 , KI, NaI. Such supplements support the production of thyroid hormone, prevent the disease of endemic goiter.

The value of sodium chloride for the human body

The formula of table salt, its composition has become vital for human health. Sodium ions are involved in the transmission of nerve impulses. Chlorine anions are necessary for the production of hydrochloric acid in the stomach. But too much salt in food can lead to high blood pressure and increase the risk of developing heart and vascular diseases. In medicine, with a large blood loss, patients are injected with physiological saline. To obtain it, 9 g of sodium chloride is dissolved in one liter of distilled water. The human body needs a continuous supply of this substance with food. Salt is excreted through the excretory organs and skin. The average content of sodium chloride in the human body is approximately 200 g. Europeans consume about 2-6 g of table salt per day, in hot countries this figure is higher due to higher sweating.

Edible table salt is a universal mineral product that has been widely used in cooking, medicine, cosmetology and animal husbandry since ancient times.

The substance is a crushed transparent crystals with a pronounced taste and odorless. Depending on the purity, in accordance with GOST R 51574-2000, four grades are distinguished: extra, highest, first and second.

Salt can be finely and coarsely ground, various additives (iodine and other minerals) may be present in the substance. They give colorless crystals a grayish, yellow or even pink tint.

The daily requirement of salt for a person is 11 grams, which is about one teaspoon. In hot climates, the norm is higher - 25-30 grams.

Nutritional value of salt:

Edible salt is essential for the proper functioning of any organism, but it is very important to follow the recommended dosage. Lack or excess of a substance can cause significant harm to health. Let's see how NaCl is useful and harmful, how it is produced and where it is used.

The chemical composition of edible salt

The formula of edible salt is known to every student - NaCl. But you will not find absolutely pure sodium chlorine either in nature or on sale. The substance contains from 0.3 to 1% of various mineral impurities.

The composition of table salt is regulated by GOST R 51574-2000, which we have already mentioned above. Regulations:

Name of indicator	Extra	Top grade	First grade	Second grade
Sodium chloride,%, not less than	99,70	98,40	97,70	97,00
Calcium-ion,%, no more	0,02	0,35	0,50	0,65
Magnesium ion,%, no more	0,01	0,05	0,10	0,25
Sulfate ion,%, no more	0,16	0,80	1,20	1,50
Potassium ion,%, no more	0,02	0,10	0,10	0,20
Iron(III) oxide,%, no more	0,005	0,005	0,010
Sodium sulfate,%, no more	0,20	Not standardized
Insoluble residue,%, no more	0,03	0,16	0,45	0,85

According to the same GOST, salt is a crystalline bulk product without impurities, except for those associated with its production. Sodium chloride has a salty taste without foreign aftertastes. In the salt of the highest, first and second grade, there may be dark particles, within the content of iron oxide and a water-insoluble residue.

Salt production

Methods for the extraction of sodium chloride have not changed much since ancient times, and the production of the substance is available in almost every country. Let's name the main methods:

• Evaporation in special sea water tanks. In this case, the composition usually includes many useful elements, including iodine.
• Extraction from the bowels of the earth in quarries and mines - such a substance contains almost no moisture and impurities.
• Washing out and evaporating the brine, thus producing salt of the "Extra" variety, it is distinguished by the highest degree of purification.
• Collecting from the bottom of salt lakes, this is how self-planting salt is obtained, which, like sea salt, contains many mineral elements necessary for organisms.

Salt types

Today there are many types of salt. Among them there are, one might say, classic and exotic. The first have long been included in our diet. They have long been used to this day in cooking and the creation of various medicinal and cosmetic products:

• Rock salt - ordinary salt without special impurities.
• Iodized salt - sodium chloride, which is artificially enriched with iodine, it is very popular in regions where people suffer from iodine deficiency.
• Fluoridated salt - enriched with fluorine is good for teeth.
• Dietary salt has a reduced sodium content, which makes it taste slightly different.

Exotic types of salt are used in various cuisines of the world, including volcanic Indian salt, Himalayan pink, French smoked and many others. Such products differ in shades and the presence of specific flavors.

Beneficial features

Salt is not produced by the body on its own, but is very important in metabolic processes. Chlorine is needed for the synthesis of hydrochloric acid in the stomach, as well as other substances that are responsible for the breakdown of fat. And sodium ensures the correct functioning of the muscles and the nervous system, it affects the condition of the bones and the absorption of nutrients by the large intestine.

Salt is involved in metabolic processes at the cell level, thanks to it the tissues receive the required amount of elements. The sodium-potassium compound is responsible for the penetration of amino acids and glucose through the cell membrane.

INTRODUCTION

The 21st century is a time when all the conditions for a comfortable life have already been created for people: they have apartments, beautiful and fast cars, smart robots, computers. In almost every home, factories, hospitals and schools there is a large number of various equipment and devices that facilitate the work of people, their life and life in general. Humanity is already so accustomed to washing machines and dishwashers, cell phones, escalators, the Internet and spaceships that it is difficult for us to imagine how people lived without all this in the recent past.

But there are also simple things in life that we do not attach much importance to and take for granted. A toothbrush, matches, a spoon, water, sugar... Without such seemingly simple things, people cannot live “comfortably”. Salt is one of those things. Salt has always been of great importance for a person and was valued very dearly. And even today people could not do without it.

Salt is a mineral natural substance and a very important component of human food. There is evidence that the extraction of table salt was carried out as far back as III-IV thousand years BC in Libya. Salt is evaporated from water, mined from the bowels of the earth, from sea water. The world's geological reserves of salt are practically inexhaustible.

For many centuries, salt has been a source of enrichment for merchants and entrepreneurs. Salt has always been treated with respect and sparingly. Hence the popular sign: "Scattered salt - to a quarrel." Salt in the old days was called the ruler of life and death. She was sacrificed to the gods. And sometimes they worshiped her as a deity. For the sake of extracting salt, they spared neither labor nor strength. And, having obtained it, they protected it as a great blessing. Salt served as a measure of wealth, power, tranquility. Salt is a pledge of fidelity.

Nowadays, salt is no longer valued so dearly. You can buy it at any grocery store and it's very inexpensive. But, nevertheless, it does not cease to play a very important role in human life. People use it not only for food, but also in everyday life, medicine, and industry.

It seems that a lot of it is needed - a pinch, a handful. You can't eat without salt and bread. Deprive a person of salt - he will get sick, die.

People in different countries eat different foods. And only one product is the same everywhere - table salt. In mineralogy, it is called halite, in technology and in everyday life - table or edible salt, and in chemistry - sodium chloride. It is necessary for the preparation of various dishes. Even sweet cakes! People cannot live without salt. That is why some peoples of Africa once paid for 1 kg of salt for 1 kg of golden sand.

I was very interested in a very simple-looking table salt, and it turned out that you can learn a lot of interesting and informative things about it.
Object of study became salt, subject of study– the study of some of its properties.

Objective: find out the role of salt in human life and the world around.

Work tasks:
1. learn about the composition and properties of salt;
2. consider the value of salt for people in the past and present;
3. learn about the harm that salt does to humans and the environment;
4. try to grow salt crystals at home.

CHAPTER I. SALT - WHAT IS IT?

1.1. Salt for man in ancient historical periods

If we turn to history, we can see how valuable this substance was for a person.

Salt was stockpiled in case of disasters and paid with it instead of money. The Latin word “salarium” and the English word “salary”, meaning “salary”, “salary”, are of “salt” origin. Its value was equal to gold. In the Roman Empire, legionnaires were paid salaries in salt. This is where the word "soldier" comes from.

Once upon a time in Holland there was a painful execution. The doomed received only bread and water, and they were completely deprived of salt. After a while, these people died, and their corpses began to decompose instantly.

In Russia, back in the 16th century, the well-known Russian businessmen Stroganovs received the largest income from salt mining. The Stroganovs were the largest saltworkers. They lived in the Perm region. The Kama area was very rich in salty groundwater outlets. It was salt that glorified the Perm Territory at that time throughout Russia. From here and from the foothills of the Urals, salt was sent to Moscow, Kazan, Nizhny Novgorod, Kaluga, and even abroad.

At the end of the 18th - beginning of the 19th centuries in Africa, where some areas are poor in salt, the English doctor and traveler Mungo Park saw negro children who licked pieces of rock salt with pleasure. And he himself said about this: “the constant use of plant foods excites a painful longing for salt to such an extent that it cannot be described properly.”

Salt was a very expensive commodity. Lomonosov wrote that at that time four small pieces of salt in Abyssinia could buy a slave. In Kievan Rus, they used salt from the Carpathian region, from salt lakes and estuaries on the Black and Azov Seas. Here it was bought and taken to the North. Salt was served on the table as a sign of prosperity and well-being. It was so expensive that at solemn feasts it was served on the tables of only distinguished guests, while the rest dispersed “without salty slurping”. After the accession of the Astrakhan Territory to the Moscow state, the lakes of the Caspian region became important sources of salt. She was simply raked from the bottom of the lakes and taken on ships up the Volga. And still it was not enough, and it was expensive. For this reason, discontent of the lower strata of the population arose, which developed into an uprising known as the Salt Riot (1648). In 1711, Peter I issued a decree on the introduction of a salt monopoly. Salt trade became the exclusive right of the state. The salt monopoly lasted for more than a hundred and fifty years and was abolished in 1862.

A person cannot do without salt, but there are other examples. Chukchi, Koryak, Tungus, Kirghiz, living in saline steppes, do not use salt at all, eating only meat and milk.

1.2. From the history of the development of salt deposits in Russia

The development of deposits in Russia has its own history and legends. A long time ago, in the dry Volga steppe, near the Big God Do mountain, a Kazakh legend tells, there lived a bai. The biggest wealth of the bai was a beautiful daughter. And she fell in love with the shepherd. Upon learning of this, the bai ordered his execution. The girl burst into tears. Days, weeks passed, tears poured and poured from her eyes. This is how the salt lake Baskunchak appeared in the steppe, or the people call it the “Lake of Tears”.

Back in the time of Tsar Peter I, an expedition visited the lake to determine what kind of salt it was and whether it was possible to fish it. It was established that fishing is possible, the salt in Baskunchak is especially good - “clean ... like ice”. But only in 1774 he decided to start mining lake salt.

Lake Elton has a large supply of table salt, but Lake Baskunchak is even richer in this salt, which is currently the main raw material base in the Lower Volga region.

For more than five hundred years, the city of Solikamsk has existed in the Urals, stretching along the banks of the Kama's tributary, the Usolka River. It has long been famous for its salt. Many millions of years ago there was a huge sea here. Finally, the time came when the Permian Sea disappeared. From him there were layers of salt several hundred meters thick, covered, like a thick blanket, with layers of clay, limestone, sand. Groundwater erodes salt deposits hidden in the earth and flows underground in salty streams and rivers. From time immemorial, local residents, hunters, fishermen have found salt springs and springs and used the brine. In 1430, the Novgorod merchants Kalashnikovs built the first salt works in Solikamsk. The brine was pumped out of the ground through wooden pipes and evaporated in large iron pans. Salt mining in those days was a profitable business. Salt was expensive. For a pood of salt they gave several poods of bread.

1.3. The structure of salt crystals

Table salt is the only mineral that is directly consumed in food. Pure table salt consists of sodium chloride NaCl. In nature, salt occurs in the form of the mineral halite - rock salt. Table salt is used in food after industrial cleaning of halite. Halite is formed in the form of crystals from colorless to white, light and dark blue, yellow and pink. The color is due to impurities.

In a solid salt, sodium and chlorine atoms are arranged in a certain order, forming a crystal lattice. All crystals are salty in nature. The salt-like character is understood as a certain set of properties that distinguishes these crystals from other crystalline substances. Due to the fact that attractive forces propagate equally in all directions, the particles at the lattice sites are relatively tightly bound. Therefore, substances such as salt are solid (crystalline) at room temperature. When the crystals are heated over time, the lattice is destroyed and the solid passes into the liquid state (at the melting point). The melting point of salt is relatively high, and the boiling point is very important.

NaCl T. pl., 0 C 801 T. kip., 0 From 1465

A typical property of a salt is that its aqueous solution is capable of conducting an electric current.

1.4. Types of salt and its main deposits

Among all the salts, the most important is
which we simply call salt.
A. E. Fersman

Sodium chloride is found in nature in a ready-made form. It is found everywhere in small quantities. But it is especially abundant in sea water and in salt lakes and springs; in large masses it is found in the form of solid rock salt.

It is estimated that the sea water of all seas and oceans contains approximately 50 10 15 tons of various salts. This salt could cover the entire globe with a layer 45 m thick. Salt accounts for most of the 38 10 15 tons. One liter of ocean water contains about 26-30g. table salt. In closed seas, where large rivers flow, the salinity is lower (Black, Caspian), while in the seas (Red, Mediterranean, Persian) the salinity is higher than the average ocean, because there is little precipitation and there is no inflow of fresh water, as well as significant evaporation. In the polar regions, the salinity of the water is greater, since the resulting ice contains little salt.

So, the salinity of sea water depends on evaporation, melting and the formation of ice, precipitation and the influx of fresh water from land.

Large amounts of salt are found in salt lakes. On the territory of our country, the Elton and Baskunchak lakes are especially rich in salt reserves. Salt reserves here are almost inexhaustible. Eltonskoye Lake covers an area of ​​205.44 km 2, and its bottom is covered with a layer of sodium chloride more than 5 m thick. Lake Baskunchak is located 53.5 km from the Volga. It occupies a surface of 190 km 2, and there are three layers of salt on it: the upper one, now being developed, is 6.5 and 9 m, the middle one is 2 m and the lower one is over 13 m, and the salt reserve in only one upper layer is estimated at approximately at 720 million m 3. The depth of the lake is not more than half a meter in winter and spring, while in summer this layer of water evaporates. This lake is located on top of a salt mountain, which goes down to a depth of more than a kilometer. This salt is 99% NaCl.

Solid or rock salt forms huge mountains underground, not inferior in size to the high peaks of the Pamirs and the Caucasus. The base of this mountain lies at a depth of 5–8 km, and the peaks rise to the earth's surface and even protrude from it. Giant mountains are also called salt domes. At high pressures and temperatures, salt in the bowels of the earth becomes plastic. In this case, the salt will lift, or pierce the rocks lying above it. Huge underground mountains of rock salt are located on the Caspian lowland, in the spurs of the Urals, in the mountains of Central Asia. Tajikistan has the highest salt domes, one of which rises to a height of 900 meters. Germany and Poland are rich in rock salt deposits.

According to the method of extraction, salt is divided into several types:
stone. It is mined by mining, using underground mining.
self-planting salt or lake salt, is extracted from the layers at the bottom of salt lakes;
garden salt is obtained by evaporating or freezing estuaries from the water;
evaporated salt is obtained by evaporation from groundwater.

Which of these salts prevails daily on our table? It is either stone or self-planting.

CHAPTER II. SALT: BENEFITS OR HARM?

2.1. Salt - "white death"?

In the 1960s, with the light hand of Herbert Shelton and Paul Bragg, table salt was dubbed "white death", and this statement still exists today. It all started with the announcement of salt as the culprit of hypertension, kidney failure, coronary heart disease and obesity. This is partly true.

So, salt is an important element that ensures the vital activity of man and the animal world, as well as a commodity that has a huge industrial application. Salt is the basis for the production of chemical products (chlorine and caustic soda), on the basis of which many plastics, aluminum, paper, soap, and glass are made. According to experts, salt in modern conditions directly or indirectly has over 14 thousand areas of application.

Sodium, which is part of the salt, is one of the necessary for the implementation of the vital functions of the human body. In our body, about 50% of all sodium is in the extracellular fluid, 40% in the bones and cartilage, and about 10% in the cells. Sodium is found in bile, blood, cerebrospinal fluid, pancreatic juice, and human milk. It is also necessary for the normal functioning of nerve endings, the transmission of nerve impulses and muscle activity, including the muscles of the heart, as well as for the absorption of certain nutrients by the small intestine and kidneys. It must be borne in mind that we consume sodium not only with table salt, but also with other sodium compounds in the form of preservatives (sodium nitrate), flavoring agents (monosodium glutamate) or baking powder (sodium bicarbonate).

Chlorine, in turn, is involved in the formation of special substances that promote the breakdown of fats. It is necessary in the formation of hydrochloric acid - the main component of gastric juice, takes care of the excretion of urea from the body, stimulates the work of the reproductive and central nervous systems, promotes the formation and growth of bone tissue. Human muscle tissue contains 0.20-0.52% chlorine, bone - 0.09%; the bulk of this trace element is found in the blood and extracellular fluid.

Salt is involved in water-salt metabolism and plays an important role in the absorption of certain nutrients in the body. For a normal person under normal, non-extreme conditions, the consumption of salt is approximately the same: 10 g in the form of natural products and 3–5 g for salting food during cooking and salting during meals. At the same time, it is imperative to take into account that an excess of salt in the body is harmful and can lead to various diseases. Therefore, everything should be in moderation, do not go to extremes.

2.2. The use of salt in everyday life

It is terrible to think what would happen if people did not discover the beneficial property of salt - to save food from decay? But who was the first to discover the beneficial property of salt to preserve food? Moreover, to give them a special attractive taste? You can travel all over the world and you won't know. Only in Holland will the name of the discoverer be named.

From time immemorial people have been catching and salting herring here. She was fed, she was sold to other countries. According to legend, a thousand years ago, the method of salting herring was discovered by the fisherman Bekkel from the small seaside village of Bulikta. Here, as a “benefactor of the state”, a monument was erected to him.

What properties of salt are used in food preservation? People use salt very widely in everyday life, when preserving and salting food products: fish, meat, vegetables, mushrooms, etc. The fact is that salt has a unique property - it kills bacteria and microbes that cause rotting and spoilage of food. The production of canned meat and fish is based on the same property. Such products do not deteriorate for a very long time, they are stored for a long time and can be used for food even several weeks after their preparation.

2.3. The use of salt in medicine

However, the use of salt is not limited to cooking. Salt is also useful from a medical point of view. The mineral iodine is added to table salt, and iodized salt is obtained. It is used to prevent iodine deficiency in the body, which can lead to thyroid disease. Recently, it has become customary to add another mineral substance to salt - fluorine (salt fluoridation). Its use is a good prevention of caries.

Dietary salt is a substitute for table salt, in which another element is presented instead of sodium, most often potassium. However, potassium chloride differs in taste from sodium chloride, and most often its taste is considered unpleasant. Therefore, varieties of dietary salt containing both sodium chloride and other compounds are offered on the consumer market. It should also be borne in mind that potassium chloride can not always serve as an alternative to regular table salt. So, in acute renal failure, dietary salt can be eaten only after consulting a doctor.

Many people like to take baths with salt. For baths, as a rule, sea salt is used. Such procedures well cleanse the skin and tone it. Sea salt has a good effect on the human nervous system. For a long time, people came to the Turkmen lake Molla-Kara to be treated for diseases of the nerves and joints. The water of the lake is one and a half times saltier than the water of the Dead Sea. To this day, it serves as a reliable medicine - people come here from all over the country! And the salty water of the underground lake is supplied to the baths of the Moscow balneary. Snow-white crystals are also necessary for obtaining a number of medicines: calomels, sublimes. Without it, you cannot prepare pyramidon tablets - a cure for headaches. Sometimes salt helps recovery, although it does not heal itself. In hot countries or hot workshops, where workers lose a lot of salt with sweat, it is advised not to drink water, but a weak solution of table salt. Salt mines are also equipped with facilities for the treatment of asthma patients.

Sodium chloride is used to obtain saline. Saline is a 0.85% NaCl solution in water. How much sodium chloride is found in human blood. In diseases, as a result of which the body loses a large amount of water, a saline solution is poured into a person.

2.4. The use of sodium chloride in industry

Salt is also a commodity that is widely used in industry. It is the basis for the production of chemical products, on the basis of which many plastics, aluminum, paper, soap, glass are produced, in the processing of furs, rawhide. Salt is used in the processing of furs and leather, in the manufacture of salt batteries and all kinds of filters.

But the main consumer of salt is the chemical industry. It uses not only salt itself, but both elements that make it up. Salt is decomposed by electrolysis of its aqueous solution. At the same time receive chlorine, hydrogen and caustic soda. From a solution of caustic soda, after evaporation, a solid alkali is obtained - caustic.

CHAPTER III. SALT CONSUMPTION

3.1. Soil reserves of salt in the Altai Territory

Salt reserves in the Altai Territory almost completely cover the necessary needs of the population. Basically, these are salt lakes of the Kulunda steppe, Slavgorodsky, Burlinsky, Mikhailovsky and a number of other regions of the region.

Lake Burlinskoe- drainless salt lake in the Slavgorod district of the Altai Territory, located in the western part of the Kulunda plain, 18 km northwest of the city of Slavgorod. The area of ​​the lake is 31.3 km 2, the average depth is less than 1 meter, the maximum depth reaches 2.5 m. A thick layer of Glauber's salt lies under a layer of silt up to 0.5 m thick.

In winter (November to March), the lake level usually rises. This is due not only to the influx of groundwater in the absence of evaporation, but also to the absence of ice cover, since solid atmospheric precipitation, falling into a salt lake, turns into water. The water in the lake is salty and is the largest deposit of table salt in Western Siberia. Salt reserves in Lake Burlinskoye are about 30 million tons.

Kuchuk lake (Kuchuk)- a bitter-salty lake in the Blagoveshchensky district of the Altai Territory on the Kulunda plain, the second largest lake in the Altai Territory after Kulunda, located 6 km to the north. Area 181 km2, length 19 km, width 12 km, maximum depth 3.3 m. Snow supply; does not freeze in winter.

Kuchuk lake has a silted bottom, covered with a layer of mirabilite in the middle. The average thickness of the layer of crystalline sodium sulfate at the bottom is 2.5 m, with reserves of tens of millions of tons of common salt and magnesium chloride. In 1960, a large chemical industry enterprise Kuchuksulfat was established near the lake. Salt reserves in Lake Kuchuk are 56.8 million tons.

Raspberry- a lake in the Mikhailovsky district of the Altai Territory, 10 km south of the village of Mikhailovskoye. This is a drainless, bitter-salty lake. It belongs to the group of Mikhailovsky lakes (Tanatar). The lake is unique in the color of the water of a raspberry hue, a distinct pink-raspberry hue gives the water a special look of small plankton crustaceans living in the lake. The area of ​​the lake is 11.4 km2. On the shore is the village of Raspberry Lake, where a chemical enterprise operates using local raw materials.

Lake Gorkoe It is located in the system of lakes of the Barnaul Ribbon Forest in the Novichikhinsky District of the Altai Territory. The length is about 25 km, the maximum width is about 3.8 km. The lake is bitter-salty.
Industrial salt production was carried out on Lake Burlinskoye, however, it has also been suspended since December 2009.

3.2. The results of the study of salt consumption by the population of Barnaul

According to the study, the consumption of table salt by the population in the city of Barnaul in the winter season is up to 3 times less than in summer and early autumn. To come to a conclusion, how much salt is sold on average per day in the city, I interviewed the sellers of ten large stores in the city. I found out that on average, every 300 shoppers buy 1 kilogram of salt per day, i.e. out of 598,000 residents of the city, 2,000 people buy a pack of salt, which is about 2,000 kg or 2 tons per day.

3.3. Findings from a Study on My Family's Salt Consumption

There are 5 people in my family. I decided to find out how much salt our family eats per day.
One pack of salt (1 pack of salt = 1kg = 1000g) we use in winter for 65 days. So, per day, each family member has:
1000g: 5 (family members) : 65 days = 3.1g (pack of salt)

Output: each member of our family receives approximately
3.1 grams of salt as a food supplement, which corresponds to the norm (norm: no more than 3-5g). However, we still need to think about the amount of salt consumed. Moreover, with hypertension and kidney disease (namely, my family members have these diseases!) The amount of salt should be reduced!

3.4. The results of a study of table salt intake in my class

I wondered how many of my peers like salty food. I asked a few simple questions to students in grades 5-7 of schools in the city of Barnaul (see the questionnaire).
588 people took part in my survey. The results of the survey I reflected in the table:

I wondered if the use of salt is connected with the diseases of my classmates? As can be seen from the table, many of those who love "salty" often get sick, and some suffer from various chronic diseases.
Salt contributes to the retention of water in the body, which, in turn, leads to an increase in blood pressure. Therefore, doctors recommend reducing the daily intake of table salt, especially with hypertension, obesity, problems with the kidneys and the nervous system.

If the salt balance is disturbed, muscle weakness, heart cramps, loss of appetite, unquenchable thirst, fatigue appear, which naturally interferes with full-fledged study and sports.
I also became interested in what products with a salt content my peers prefer. The survey data are presented in the table:

Output: most of my peers love salty food and do not think that this can lead to various diseases of the body.

CHAPTER IV. SALT DETECTION IN VARIOUS PRODUCTS

4.1. Detection of sodium and chlorine particles in common salt solution, fruit and vegetable juices

4.1.1. Detection of particles of sodium and chlorine in a solution of table salt.

Dissolve 5 g of salt in 50 g of water. I add a solution of silver nitrate drop by drop to a portion of the resulting solution. The precipitation of a white cheesy precipitate indicates the presence of chlorine particles in the salt.
A drop of the test solution was introduced into the flame of an alcohol lamp. The flame turned yellow, indicating the presence of sodium particles in the composition of the salt.

Output: table salt contains particles of sodium and chlorine.

4.1.2. Detection of chlorine and sodium particles in fruit and vegetable juices

For the experiment, I took green apples, oranges, carrots, potatoes, cucumbers, tomatoes, cabbage. I carefully crushed fruits and vegetables, squeezed the juice and filtered it.
I took an equal amount (1 ml each) of the resulting juice and added a solution of silver nitrate dropwise to each portion. In all samples, a white cheesy precipitate occurred, but in different amounts.
Apples have a high content of chlorine particles, oranges are much less.
In carrots, potatoes, cucumbers, tomatoes, I found a low content of chlorine particles, and in cabbage there are much more of them.
A drop of the studied solutions was alternately introduced into the flame of an alcohol lamp. The flame turned yellow, indicating the presence of sodium particles in the composition of the salt.

Output: fruits and vegetables contain some salt.

Thus, any living organism requires the use of salt. I made sure that vegetables and fruits contain enough salt for the life of the body. Therefore, there is no particular need to get involved in the consumption of salt from a pack.

CHAPTER V. EFFECT OF SALT ON SKIN AND METAL

The question of what salt is and how people use it in their lives arose in my mind when one winter I noticed that upon returning home from the street, the shoes dry out and white stains remain on them. I asked my mother and she explained to me that these traces are left by salt, which, together with sand, is used to sprinkle roads in winter against ice.

It turns out that despite all its benefits, salt can be harmful and even dangerous to humans and the environment. Snowdrifts are cleared with special equipment, and ice is fought with the help of a sand-salt mixture, which is scattered on the roads. Why exactly salt? Because the freezing point of salt water is much lower than zero degrees. Therefore, wet snow does not freeze, but turns into a "porridge", which is easily removed from the roadway. It would seem to be useful again. But the fact is that technical salt is usually used for such mixtures. This salt is of the lowest quality, with a large amount of toxic impurities. A huge amount of such mixtures is poured out during the winter on the roads of the city. The damage they cause is most pronounced in the spring, when the snow begins to melt. Poisonous substances are absorbed into the soil and gradually poison it. It is for this reason that the trees growing along the roads have a gray, withered appearance, and the grass and flowers practically do not grow. This is due not only to harmful emissions from vehicles and industrial enterprises, but also to the unreasonable use of salt mixtures.

Together with melt water, salt and its chemical impurities enter the city reservoirs. This leads to the fact that over time, it becomes impossible for either fish or plants to live in such poisoned water.

The sand-salt mixture corrodes car tires and spoils the metal parts of cars. The metal rusts, the car has to be repaired often. Our shoes deteriorate in the same way.

I decided to experience the negative effect of salt on the skin and metal.

5.1. The effect of salt on the skin

I decided to observe the effect of salt on the skin. For the experiment, I needed a piece of skin, water and salt. I prepared a strong saline solution (dissolved 100g of salt in 300g of water); placed a piece of skin in saline solution. The results of observations were recorded in a journal for 7 days.

A strip of leather 10 cm long was half placed in a container with saline. She gradually soaked in salt water. Already on the second day, salt crystals formed in the upper part of the strip, which was above the solution. And on the seventh day, almost the entire upper part of the strip was overgrown with crystals and a dense salt crust formed. The skin itself became hard. He took out a strip of leather from the container and dried it. The skin hardened even more. The salt crust was brittle, and under it the skin took on a whitish color. White plaque was not cleaned off - the salt was deeply ingrained into the skin. She lost her elasticity and became very fragile.

Output: salt, indeed, has a destructive effect on shoes and it is very important and necessary to take care of it! If we want to prolong the service life of boots and boots, it is necessary to wash them every day, dry them thoroughly and clean them with cream. This will prevent salt and other chemicals from penetrating into the leather and keep the shoes strong and looking good.

5.1. Effect of salt on metal

For the experiment, I needed an ordinary nail. I immersed it in the same salt solution as the leather strip. On the second day, the nail began to rust, and salt crystals appeared at the junction of the solution-air, which grew every day. The color of the water has changed. The water has turned yellow. On the seventh day the water turned brown.

Output: salt has a negative effect on metal objects, accelerates the process of rusting of metal objects, which leads to their destruction.

CHAPTER VI. GROWING SALT CRYSTALS

Crystals are substances in which the smallest particles are "packed" in a certain order. As a result, during the growth of crystals, flat faces spontaneously appear on their surface, and the crystals themselves take on a variety of geometric shapes. Who has not admired snowflakes, the variety of which is truly endless! Back in the 17th century. the famous astronomer Johannes Kepler wrote a treatise “On Hexagonal Snowflakes”, and after the 3rd century, albums were published containing collections of enlarged photographs of thousands of snowflakes, and not one of them repeats the other.

The origin of the word "crystal" is interesting (it sounds almost the same in all European languages). Many centuries ago, among the eternal snows in the Alps, on the territory of modern Switzerland, they found very beautiful, completely colorless crystals, very reminiscent of pure ice. Ancient naturalists called them that - "crystallos", in Greek - ice; This word comes from the Greek "krios" - cold, frost. It was believed that ice, being in the mountains for a long time, in severe frost, petrifies and loses its ability to melt. One of the most authoritative ancient philosophers, Aristotle, wrote that “crystallos” is born from water when it completely loses its warmth.” The Roman poet Claudian in 390 described the same thing in verse:

In the fierce alpine winter, ice turns to stone.
The sun is not able to then melt such a stone.

A similar conclusion was made in ancient times in China and Japan - ice and rock crystal were designated there by the same word. And even in the 19th century poets often combined these images together:

Barely transparent ice, fading over the lake,
crystal covered motionless jets.
A.S. Pushkin "To Ovid"

There are several ways to grow crystals. One of them is the cooling of a saturated hot solution. If the cooling is carried out quickly, the excess substance will simply precipitate. If this sediment is dried and examined through a magnifying glass, then many small crystals can be seen.

Another method for obtaining crystals is the gradual removal of water from a saturated solution. The "extra" substance crystallizes. And in this case, the slower the water evaporates, the better the crystals are obtained.
The third method is the growth of crystals from molten substances by slowly cooling the liquid.

When using all methods, the best results are obtained if a seed is used - a small crystal of the correct shape, which is placed in a solution or melt. In this way, for example, ruby ​​crystals are obtained. Growth of crystals of precious stones is carried out very slowly, sometimes for years. If, however, to accelerate crystallization, then instead of one crystal, a mass of small ones will turn out.

I have grown common salt crystals by cooling a hot saturated seeded solution in an open and closed vessel at the same temperature and growth conditions.

Observation diary

Output: By deposition on a foreign body (seed) placed in a supersaturated solution, the salt crystallizes.

Salt crystal after 7 hours in an open container

The formation of a transparent dome

This is how a salt crystal grew

CONCLUSION

I was very interested in a very simple-looking table salt, but it turned out that you can learn a lot of interesting and informative things about it.

The world's salt reserves are practically inexhaustible. A person uses for himself those sources that allow him to get more accessible, cheap, pure salt.

Working on this topic, I realized that these colorless solid crystals, highly soluble in water, which are eaten in small quantities, play a huge role in the life of living organisms (both animals and humans).

Obviously, the importance and necessity of salt in our lives cannot be underestimated. But, at the same time, we must not forget about the harm that it can cause with illiterate use. I think that almost any useful and necessary product can become dangerous for humans and nature if it is used unreasonably.

I've done the work:
7 B class student
CHEVERDA Ilya

Supervisor:
Chemistry teacher
Cheverda Irina Viktorovna

MBOU "Gymnasium No. 40"
Oktyabrsky district
city ​​of Barnaul