Physical state of table salt. Table salt, chemistry. Table salt Boiling point of table salt and sugar

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. Dissolves in liquid ammonia and enters into exchange reactions. Density of NaCl 2.165 g/cm 3, melting point 800.8° C, boiling point 1465° C.

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

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

Perhaps one day, in the absence 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 people hid the meat they had harvested for future use in sea water to protect it from birds of prey and insects, and then discovered that it acquired a pleasant taste. Observant hunters of primitive tribes could notice that animals love to lick salt licks - white crystals of rock salt protruding here and there from the ground, and tried adding salt to their food. There could be other cases of people's first acquaintance with this amazing substance.

Pure table salt, or sodium chloride NaCl a colorless, non-hygroscopic (does not absorb moisture from the air) crystalline substance, soluble in water and melting at 801 ° C. In nature, sodium chloride occurs in the form of a mineral halite rock salt. The word "halite" comes from the Greek "halos", 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 rock layer located above the salt layer turns it into a viscous, plastic mass. “Floating up” in places of low pressure of the covering rocks, the layer of salt forms salt “domes” that come 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. Blue halite crystals are found, but very rarely. This means that for a long time in the depths of the earth they were in the vicinity of rocks containing uranium and were exposed to radioactive radiation.

In the laboratory you can also obtain blue crystals of sodium chloride. This does not require radiation; you just need to heat a mixture of table salt NaCl and a small amount of sodium metal Na in a tightly closed vessel. The metal can dissolve in salt. When sodium atoms penetrate 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 in the crystal where Cl ? . Such unusual places inside the crystal, occupied by electrons instead of ions, are called “vacancies”.

When the crystal cools, some vacancies combine, which is what causes the blue color to appear. By the way, when a blue salt crystal 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 cannot live without salt.” Military clashes occurred over rock salt deposits, and sometimes salt shortages 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 - the salt shaker. Soldiers were often paid in salt, and officials received salt rations. As a rule, salt springs were the property of rulers and crowned heads. In the Bible there is an expression “drinking salt from the king’s palace,” meaning a person receiving support 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 among the ancient Jews were sprinkled with salt, and in Catholic churches, during baptism, a crystal of salt was placed in the baby’s mouth.

It was the custom of the Arabs, when approving solemn agreements, to serve a vessel with salt, from which, as a sign of proof and guarantee of constant friendship, the persons who entered into the agreement “covenant of salt” ate several grains of it. “Eating a peck of salt together” among the Slavs means getting to know each other well and making friends. According to Russian custom, when they bring bread and salt to guests, they thereby wish them health.

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

Table salt was also part of the most ancient medicines; it was credited with healing properties, cleansing and disinfecting effects, and it has long been noted that table salt from different deposits has different biological properties: the most useful in this regard is sea salt. IN Herbalist, published in Russia in the 17th century, it is written: “Two essences of salt, one was dug from the mountain, and the other was found in the sea, and which is from the sea, that lutchi, and besides sea salt, that lutchi, which is white.”

However, when consuming salt, you must observe moderation. It is known that the average European daily absorbs up to 15 g of salt with food, while the average Japanese consumes about 40 g. It is the Japanese who 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 he needs. Cells swell from its excess, compress blood vessels, so blood pressure rises, which causes the heart to work 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 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 inviting trouble and losing health.

In ancient times, people used several methods for extracting table salt: natural evaporation of sea water in “salt ponds”, where sodium chloride NaCl “sea” salt precipitated, boiling water from salt lakes to obtain “evaporated” salt, and breaking out “rock” salt in underground mines. All these methods produce 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, table salt accounts for 24 g. The technology for producing 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 makers doused logs with sea water, and then burned them and extracted salt from the ashes. Later, salt waters were evaporated 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 bush branches. Evaporation of the salt solution in air was also carried out in a very primitive way, by pouring the brine over a wall made of bundles of brushwood and straw.

Salt making, the oldest of the chemical crafts, arose in Rus', apparently, at the beginning of the 7th century. The salt mines belonged to the monks, who were favored by the Russian tsars; they were not even charged a tax on the salt they sold. Salt boiling brought huge profits to the monasteries. Brines were extracted not only from lakes, but also from underground salt springs; boreholes that were built for this purpose in the 15th century. reached a length of 6070 m. Pipes made of solid wood were lowered into the wells, and the brines were evaporated in iron pans on a wood firebox. In 1780, more than one hundred thousand tons of salt were boiled in Russia in this way...

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

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

Stepin B.D., Alikberova L.Yu. Chemistry book for home reading, 2nd ed. M., Chemistry, 1995
Lidin R.A. and etc. Chemical properties of inorganic substances: Textbook. manual for universities / R.A. Lidin, V.A. Molochko, L.L. Andreeva; edited by R.A.Lidina. M., Chemistry, 1996
Alikberova L.Yu. Entertaining chemistry: A book for students, teachers and parents. M., AST-PRESS, 1999
Stepin B.D., Alikberova L.Yu., Rukk N.S. Household chemicals. Chemistry in everyday life and for every day. M., RET, 2001

More than 10 million organic and more than 500 thousand inorganic compounds are known to chemists today. Among them there are complex in structure and properties that are used only for chemical or medical purposes. And there are those that are not at all complicated and are very common in everyday life. But that doesn’t make them any less important and significant. One of these substances is table salt. In everyday life it is also called food, and in the chemical industry it is called sodium chloride or sodium chloride. In the technology industry it is called the mineral it forms in nature, halite, and also rock salt or hard rock salt. Let's take a closer look at the physical state of table salt, structure, properties, production, use and history of its introduction into mass consumption.

In what states does table salt exist?

What is it and how does it happen? It depends on what substance we are talking about. Every student over 7th grade can name the physical state of table salt, because this is the substance that is found in every home. Today, it is difficult for a modern person to imagine his life without it. In addition, the state of aggregation of table salt is quite obvious to the naked eye - finely or coarsely dispersed crystals of regular cubic shape. However, having dissolved salt in water, we get it in a different state of aggregation - liquid. We get the same thing if we simply melt the crystals at high temperature. The only state that is not typical for salt is gaseous. But under certain conditions you can get it.

Conditions for changing the state of aggregation

1. To obtain salt in a liquid state by melting solid crystals of natural origin, it is necessary to apply a temperature of 800 o C.
2. To transform the salt into a gaseous state, the molten crystals must be brought to a boil (about 1400 o C) and boiled until the structural components are completely converted into ions (Na + and CL -).
3. The solid state of table salt is its natural form under natural conditions.

Why does such a temperature range occur when manipulating crystals? This is explained by the structure of the crystal lattice.

Crystal cell

It is a regular face-centered cubic transparent crystal. At each corner of the cube (crystal lattice nodes) there are alternating positively charged Na + ions and negatively charged CL - ions. Due to the sharply different electronegativity of these atoms, such a strong electrostatic attraction arises between them that severe conditions (high temperature, mechanical stress) must be applied to destroy it. This is called ionic, and it is characteristic of all salts of alkali, alkaline earth and transition metals.

This is why the temperature of table salt (both melting and boiling) is so high. However, it is possible to obtain crystals not only of cubic shape, but also of pyramidal shape (eight-, twelve- and twenty-sided). To do this, you simply need to adjust the temperature of the evaporation of the salt solution in a certain way. In any case, the internal cavity of the crystals remains filled with liquid if we are talking about a solution of salt in water.

The chemical formula of sodium chloride is simple and is expressed by the elemental composition NaCL.

Physical properties of halite

The physical properties of sodium chloride can be described in several points:

• Solid crystals of white, pink, blue, violet, red. The color depends on the presence of impurities during extraction. crystal white color.
• Dissolves in water in a ratio of approximately 100/30 (30 g of salt in 100 g of water). Good solubility is explained by the presence of water dipoles, which associate sodium and chlorine ions around themselves, causing the destruction of the electrostatic attraction between them and, as a consequence, the destruction of the crystal lattice.
• Melts and boils at high temperatures (800-1400 o C).
• It has a subtle pleasant smell.
• Salty taste.

Chemical properties of sodium chloride

Like any soluble salt, sodium chloride can interact with:

• Other salts by exchange reaction (required condition: reaction of gas evolution, precipitation or formation of a poorly dissociable substance): NaCL + AgNO 3 = NaNO 3 + AgCL (white cheesy precipitate). This is a qualitative reaction to the CL - ion.
• With metals located in the EHRNM to the left of sodium: K + NaCL = KCL + Na.
• Dissociates in an aqueous solution into free ions hydrated by water dipoles: NaCL (aqueous solution) = Na + + CL - . As a result, a solution of table salt is formed, which is a strong electrolyte.
• It does not undergo hydrolysis, since it is a salt formed by a strong acid and a strong base.
• During electrolysis (action of electric current) it decomposes with the formation of free products and caustic soda (caustic): NaCL = Na + Cl 2 + NaOH.

Where is sodium chloride found in nature?

Currently, it is a substance often found in nature. And although this has always been the case, in ancient and medieval times it was considered a very expensive product. All this is due to the fact that they did not know how to extract salt from natural sources. And there are a lot of such sources in the world's reserves - halite is considered an almost unlimited natural resource. Where is salt found in nature?

1. Seas and oceans with salt water.
2. Salt lakes.
3. Salty springs.
4. The groundwater.
5. Waters of estuaries.

Halite mining

The extraction and processing of salt has its own technology, since the simply extracted substance is most often unsuitable for consumption due to the high content of foreign impurities. Halite is mined in different ways, for example:

• through underground work;
• from layers at the bottom of salt reservoirs;
• by evaporating or freezing salty sea or ocean water;
• evaporation of groundwater.

Any of the methods makes it possible to obtain halite crystals. However, to be eaten, they must undergo another type of processing - grinding. After all, hardly anyone uses a large crystal of table salt when cooking at home. Most often it is purchased in a form already purified from impurities and crushed almost into powder. There are also types of salt, iodized, fluoridated, and so on, not only for food, but also for technical purposes.

Uses of rock salt

The areas of application and use of sodium chloride are very extensive. The main ones, along with examples and results, are given in the table.

History of appearance in everyday life

Salt did not immediately appear on the tables in every home. Once upon a time it was worth its weight in gold, and in the most literal sense. Back in the 18th century, some African peoples exchanged a handful of salt for a handful of gold dust. A little later in Ethiopia, sticks of salt were the standard currency. In ancient Rome, military legionnaires were even given a monthly salary in this substance, which over time led to them being called soldiers. Children of poor African peoples simply licked stone pieces of table salt as a delicacy. In Holland it was used to punish criminals and torture. The offender was not given salt at all, and the person died in a short time.

People first learned to isolate and consume this substance in ancient times. It was then discovered that salt was found in plants. Therefore, they were burned and the ashes were used as a seasoning. Later in China they learned to evaporate salt from sea water, and the process of developing methods for its production began to move faster.

In Rus', salt was mined from lakes (the most famous in Russia so far are Elton and Baskunchak). At that time, the commercial value of the substance was a very rare phenomenon. Only a few merchants mined it, who then sold it at exorbitant prices. Only rich and famous people could afford to have salt. Over time, production and extraction improved. Different methods of extraction and processing began to be used, and today one of the most common household substances is table salt. The chemistry of this compound, properties, application in medicine and other industries became known approximately from the 16th-17th centuries.

Studying in a school course

The study of the structure and state of aggregation, as well as the chemical properties of table salt, begins from school, within the framework of a discipline such as chemistry (8th grade). Salts in the school course are studied in all their diversity in nature. Students gain an understanding of chemical basis, empirical formulas, basic physical and chemical properties. For simplicity and convenience of memorizing formulas, salts are usually located on the flyleaf of the textbook, the table of which gives an idea of ​​their solubility in water. There you can also find information on the solubility of acids, alkalis and bases.

An important characteristic of salts is their fusibility, on the basis of which their extraction in nature is also based. It is easy for students to navigate when solving problems on the fusibility of salt. The table and graphic images allow you not only to see whether a substance is fusible or refractory, but also to determine the approximate melting and boiling points. Usually such tables are also located in textbooks ("Chemistry", 8th grade). Salts must be studied in the context of sciences such as biology and physics. Therefore, many tasks for students are based on the integration of interdisciplinary connections.

Table salt is sodium chloride used as a food additive and food preservative. It is also used in the chemical industry and 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 is reflected by the conventional formula NaCl, which gives an idea of ​​the equal number of sodium and chlorine atoms. But the substance is not formed by diatomic molecules, but consists of crystals. When an alkali metal reacts with a strong nonmetal, each sodium atom gives up the more electronegative chlorine. Sodium cations Na + and anions of the acidic residue of hydrochloric acid Cl - appear. Oppositely charged particles attract each other, 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 substances of ionic structure, the names of which begin with the name of the acidic residue. The formula for table salt is NaCl. Geologists call a mineral of this composition “halite,” and a sedimentary rock “rock salt.” An outdated chemical term that is often used in manufacturing 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 reaction equations involving sodium chloride, use chemical symbols (“sodium chlorine”).

Let's carry out simple calculations using the formula of the substance:

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

The relative value is 58.44 (in amu).

2) Molar mass is numerically equal to molecular weight, but this quantity has units of measurement g/mol: M (NaCl) = 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

Fragile halite crystals are colorless or white. In nature, there are also deposits of rock salt, colored grey, 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, 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);

Preparation of sodium chloride in the laboratory

When metallic sodium reacts with chlorine gas in a test tube, a white substance is formed - sodium chloride NaCl (formula of table salt).

Chemistry provides insight into different ways of producing the same compound. Here are some examples:

NaOH (aq) + HCl = NaCl + H 2 O.

Redox reaction between a metal and an acid:

2Na + 2HCl = 2NaCl + H2.

Effect 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) = 2NaCl + H 2 O + CO 2 (gas).

All these methods are too expensive and complex for use on an industrial scale.

Production of table salt

Even at the dawn of civilization, people knew that salting meat and fish lasts longer. Transparent, regularly 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 satisfy 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 seas, oceans and salt lakes;
• layers and crusts of rock salt on the banks of salty reservoirs;
• halite crystals on the walls of volcanic craters;
• salt marshes.

The industry uses four main methods for producing table salt:

• 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 the dry residue is sodium chloride);
• using a by-product of salt water desalination.

Chemical properties of sodium chloride

In terms of its composition, NaCl is an average 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 break it. In water, the substance disintegrates, cations and anions (Na +, Cl -) are released. Their presence is due to the electrical conductivity possessed by a solution of table 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 color 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 peculiarity of the anion, which consists in a qualitative reaction to the chloride ion. When interacting with silver nitrate, a white precipitate of silver chloride precipitates in the solution (photo). Hydrogen chloride is displaced from the salt by stronger acids than hydrochloric acid: 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, so in winter a mixture of salt and sand is used on roads and sidewalks. It absorbs a large amount of impurities and, when melting, 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;
• sodium metal;
• chlorine gas;
• caustic soda and other compounds.

In addition, table salt is used in the production of soap and dyes. It is used as a food antiseptic for canning and pickling mushrooms, fish and vegetables. To combat thyroid dysfunction 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 and prevent endemic goiter.

The importance of sodium chloride for the human body

The formula of table salt, its composition has acquired vital importance 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 an increased risk of developing heart and vascular diseases. In medicine, when there is a large blood loss, patients are given physiological saline solution. To obtain it, 9 g of sodium chloride are dissolved in one liter of distilled water. The human body needs a continuous supply of this substance from food. Salt is excreted through the excretory organs and skin. The average sodium chloride content 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.

The formula of which is NaCl is a food product. In inorganic chemistry, this substance is called sodium chloride. In its crushed form, table salt, the formula of which is given above, appears as white crystals. Insignificant gray shades may appear in the presence of other mineral salts as impurities.

It is produced in various forms: unrefined and purified, small and large, iodized.

Biological significance

A crystal of table salt, which has an ionic chemical bond, is necessary for the full life and activity of humans and other living organisms. Sodium chloride takes part in the regulation and maintenance of water-salt balance and alkaline metabolism. Biological mechanisms control the constant concentration of sodium chloride in various fluids, such as blood.

The difference in NaCl concentrations inside and outside the cell is the main mechanism for the entry of nutrients into the cell, as well as the removal of waste products. A similar process is used in the generation and transmission of impulses by neurons. Also, the chlorine anion in this compound is the main material for the formation of hydrochloric acid, the most important component of gastric juice.

The daily requirement for this substance is from 1.5 to 4 grams, and for hot climates the dose of sodium chloride increases several times.

The body does not need the compound itself, but the Na+ cation and the Cl- anion. If the amount of these ions is insufficient, muscle and bone tissue is destroyed. Depression, mental and nervous diseases, disturbances in the cardiovascular system and digestive processes, muscle spasms, anorexia, and osteoporosis appear.

Chronic lack of Na+ and Cl- ions leads to death. Biochemist Zhores Medvedev noted that with the complete absence of salt in the body, one can last no more than 11 days.

Even in ancient times, tribes of cattle breeders and hunters consumed raw meat products to satisfy the body's need for salt. Agricultural tribes consumed plant foods that contained small amounts of sodium chloride. Signs indicating a lack of salt include weakness and headache, nausea, and dizziness.

Production Features

In the distant past, salt was extracted by burning certain plants in fires. The resulting ash was used as a seasoning.

Purification of table salt obtained by evaporation sea ​​water, was not carried out, the resulting substance was immediately consumed as food. This technology originated in countries with hot and dry climates, where a similar process occurred without human intervention, and then, when other countries adopted it, sea water began to be heated artificially.

Saltworks were built on the shores of the White Sea, in which concentrated brine and fresh water were obtained by evaporation and freezing.

Natural deposits

Among the places characterized by large reserves of table salt, we highlight:

• Artemovskoye field, located in the Donetsk region. Salt is extracted here using the mine method;
• Lake Baskunchak, transportation is carried out along a specially built railway;
• potassium salts were found in large quantities in the Verkhnekamskoye deposit, where this mineral is mined using the mine method;
• mining was carried out in the Odessa estuaries until 1931; currently the deposit is not used on an industrial scale;
• In the Seregovskoye deposit, brine is evaporated.

Salt mine

The biological properties of table salt made it an important economic object. As of 2006, about 4.5 million tons of this mineral were used on the Russian market, with 0.56 million tons going for food consumption, and the remaining 4 million tons going to the needs of the chemical industry.

physical characteristics

Let's look at some properties of table salt. This substance dissolves quite well in water, and the process is influenced by several factors:

• temperature;
• presence of impurities.

A crystal of table salt contains impurities in the form of calcium and magnesium cations. This is why sodium chloride absorbs water (it becomes damp in the air). If such ions are not part of table salt, this property is absent.

The melting point of table salt is 800.8 °C, which indicates the strong crystalline structure of this compound. Mixing fine sodium chloride powder with crushed ice produces a high quality coolant.

For example, 100 g of ice and 30 g of table salt can reduce the temperature to −20 °C. The reason for this phenomenon is that the table salt solution freezes at temperatures below 0 °C. Ice, for which this value is the melting point, melts in such a solution, absorbing heat from the environment.

The high melting point of table salt explains its thermodynamic characteristics, as well as its high dielectric constant - 6.3.

Receipt

Considering how important the biological and chemical properties of table salt and its significant natural reserves are, there is no need to develop an option for the industrial production of this substance. Let's look at laboratory options for producing sodium chloride:

1. This compound can be obtained as a product by reacting copper sulfate(2) with barium chloride. After removing the precipitate, which is barium sulfate, and evaporating the filtrate, crystals of table salt can be obtained.
2. When sodium exothermicly combines with chlorine gas, sodium chloride is also formed, and the process is accompanied by the release of a significant amount of heat (exothermic form).

Interactions

What are the chemical properties of table salt? This compound is formed by a strong base and a strong acid, so hydrolysis does not occur in an aqueous solution. The neutrality of the environment explains the use of table salt in the food industry.

During the electrolysis of an aqueous solution of this compound, hydrogen gas is released at the cathode, and the formation of chlorine occurs at the anode. Accumulates in the interelectrode space sodium hydroxide.

Considering that the resulting alkali is a substance in demand in various production processes, this also explains the use of table salt on an industrial scale in chemical production.

The density of table salt is 2.17 g/cm3. A cubic face-centered crystal lattice is characteristic of many minerals. Inside it, ionic chemical bonds predominate, formed due to the action of forces of electrostatic attraction and repulsion.

Halite

Since the density of table salt in this compound is quite high (2.1-2.2 g/cm³), halite is a solid mineral. The percentage of sodium cation in it is 39.34%, chlorine anion - 60.66%. In addition to these ions, halite contains ions of bromine, copper, silver, calcium, oxygen, lead, potassium, manganese, nitrogen, and hydrogen in the form of impurities. This transparent, colorless mineral with a glassy luster is formed in closed bodies of water. Halite is a product of distillation in volcanic craters.

Rock salt

It is a sedimentary rock from the evaporite group that consists of more than 90 percent halite. Rock salt is characterized by a snow-white color; only in exceptional cases, the presence of clay gives the mineral a gray tint, and the presence of iron oxides gives the compound a yellow or orange color. Rock salt contains not only sodium chloride, but also many other chemical compounds of magnesium, calcium, and potassium:

• iodides;
• borates;
• bromides;
• sulfates.

Depending on the formation conditions, the main rock salt deposits are divided into several types:

• underground salt waters;
• brines of modern swimming pools;
• deposits of mineral salts;
• fossil deposits.

Sea salt

It is a mixture of sulfates, carbonates, potassium and sodium chlorides. During its evaporation at temperatures ranging from +20 to +35 °C, the crystallization of less soluble salts initially occurs: magnesium and calcium carbonates, as well as calcium sulfate. Then soluble chlorides precipitate, as well as magnesium sulfates and sodium. The crystallization sequence of these inorganic salts can change taking into account the temperature, the rate of the evaporation process, and other conditions.

In industrial quantities, sea salt is obtained from sea water by evaporation. It differs significantly in microbiological and chemical parameters from rock salt; it has a high percentage of iodine, magnesium, potassium, and manganese. Due to the different chemical composition, there are differences in organoleptic characteristics. Sea salt is used in medicine as a treatment for skin diseases, such as psoriasis. Among the common products offered in the pharmacy chain, we highlight Dead Sea salt. Purified sea salt is also offered in the food industry as iodized salt.

Regular table salt has weak antiseptic properties. With a percentage of this substance in the range of 10-15 percent, the appearance of putrefactive bacteria can be prevented. It is for these purposes that sodium chloride is added as a preservative to food, as well as other organic masses: wood, glue, leather.

Abuse of salt

According to the World Health Organization, excessive consumption of sodium chloride leads to a significant increase in blood pressure, as a result of which kidney and heart diseases, stomach diseases, and osteoporosis often develop.

Together with other sodium salts, sodium chloride is the cause of eye diseases. Table salt retains fluid inside the body, which leads to increased intraocular pressure and the formation of cataracts.

Instead of a conclusion

Sodium chloride, commonly referred to as table salt, is a widely occurring inorganic mineral in nature. This fact greatly simplifies its use in the food and chemical industries. There is no need to spend time and energy resources on the industrial production of this substance, which affects its cost. In order to prevent an excess of this compound in the body, it is necessary to control the daily consumption of salty foods.