Every day we come across salts and don’t even think about the role they play in our lives. But without them, the water would not be so tasty, and the food would not bring pleasure, and the plants would not grow, and life on earth could not exist if there were no salt in our world. So what are these substances and what properties of salts make them irreplaceable?

What are salts

In terms of its composition, this is the most numerous class, characterized by diversity. Back in the 19th century, the chemist J. Werzelius defined a salt as a product of a reaction between an acid and a base, in which a hydrogen atom is replaced by a metal one. In water, salts usually dissociate into a metal or ammonium (cation) and an acidic residue (anion).

You can get salts in the following ways:

• through the interaction of a metal and a non-metal, in this case it will be oxygen-free;
• when a metal reacts with an acid, a salt is obtained and hydrogen is released;
• a metal can displace another metal from solution;
• when two oxides interact - acidic and basic (they are also called non-metal oxide and metal oxide, respectively);
• the reaction of a metal oxide and an acid produces salt and water;
• the reaction between a base and a non-metal oxide also produces salt and water;
• using an ion exchange reaction, in this case various water-soluble substances (bases, acids, salts) can react, but the reaction will proceed if gas, water or slightly soluble (insoluble) salts are formed in water.

The properties of salts depend only on the chemical composition. But first, let's look at their classes.

Classification

Depending on the composition, the following classes of salts are distinguished:

• by oxygen content (oxygen-containing and oxygen-free);
• by interaction with water (soluble, slightly soluble and insoluble).

This classification does not fully reflect the diversity of substances. The modern and most complete classification, reflecting not only the composition, but also the properties of salts, is presented in the following table.

Salts
Normal	Sour	Basic	Double	Mixed	Complex
Hydrogen is completely replaced	Hydrogen atoms are not completely replaced by metal	Base groups are not completely replaced by an acidic residue	Contains two metals and one acid residue	Contains one metal and two acidic residues	Complex substances consisting of a complex cation and an anion or a cation and a complex anion
NaCl	KHSO 4	FeOHSO 3	KNaSO4	CaClBr	SO 4

Physical properties

No matter how wide the class of these substances is, it is possible to identify the general physical properties of salts. These are substances of non-molecular structure, with an ionic crystal lattice.

Very high melting and boiling points. Under normal conditions, all salts do not conduct electricity, but in solution, most of them conduct electricity perfectly.

The color can be very different, it depends on the metal ion included in its composition. Ferrous sulfate (FeSO 4) is green, ferrous chloride (FeCl 3) is dark red, and potassium chromate (K 2 CrO 4) is a beautiful bright yellow color. But most salts are still colorless or white.

Solubility in water also varies and depends on the composition of the ions. In principle, all physical properties of salts have a peculiarity. They depend on which metal ion and which acidic residue are included in the composition. Let's continue looking at salts.

Chemical properties of salts

There is also an important feature here. Like the physical, chemical properties of salts depend on their composition. And also on what class they belong to.

But the general properties of salts can still be highlighted:

• many of them decompose when heated to form two oxides: acidic and basic, and oxygen-free ones - metal and non-metal;
• salts also interact with other acids, but the reaction occurs only if the salt contains an acidic residue of a weak or volatile acid or the result is an insoluble salt;
• interaction with alkali is possible if the cation forms an insoluble base;
• a reaction between two different salts is also possible, but only if one of the newly formed salts does not dissolve in water;
• A reaction with a metal can also occur, but it is only possible if we take a metal located to the right in the voltage series from the metal contained in the salt.

The chemical properties of salts classified as normal are discussed above, but other classes react with substances somewhat differently. But the difference is only in the output products. Basically, all the chemical properties of the salts are preserved, as are the requirements for the reactions.

Salts are organic and inorganic chemical substances of complex composition. In chemical theory there is no strict and final definition of salts. They can be described as compounds:
- consisting of anions and cations;
- obtained as a result of the interaction of acids and bases;
- consisting of acidic residues and metal ions.

Acidic residues can be associated not with metal atoms, but with ammonium ions (NH 4) +, phosphonium (PH 4) +, hydronium (H 3 O) + and some others.

Types of salts

Acidic, medium, basic. If all the hydrogen protons in an acid are replaced by metal ions, then such salts are called medium salts, for example, NaCl. If hydrogen is only partially replaced, then such salts are acidic, for example. KHSO 4 and NaH 2 PO 4. If the hydroxyl groups (OH) - bases are not completely replaced by an acidic residue, then the salt is basic, for example. CuCl(OH), Al(OH)SO 4 .

- Simple, double, mixed. Simple salts consist of one metal and one acid residue, for example, K 2 SO 4. Double salts contain two metals, for example KAl(SO 4) 2. Mixed salts have two acidic residues, e.g. AgClBr.

Organic and inorganic.
- Complex salts with a complex ion: K 2, Cl 2 and others.
- Crystal hydrates and crystal solvates.
- Crystalline hydrates with molecules of water of crystallization. CaSO 4 *2H 2 O.
- Crystal solvates with solvent molecules. For example, LiCl in liquid ammonia NH 3 gives LiCl*5NH 3 solvate.
- Oxygen-containing and oxygen-free.
- Internal, otherwise called bipolar ions.

Properties

Most salts are solids with a high melting point and do not conduct electricity. Solubility in water is an important characteristic; on its basis, reagents are divided into water-soluble, slightly soluble and insoluble. Many salts dissolve in organic solvents.

Salts react:
- with more active metals;
- with acids, bases, and other salts, if the interaction produces substances that do not participate in further reactions, for example, gas, insoluble precipitate, water. They decompose when heated and hydrolyze in water.

In nature, salts are widely distributed in the form of minerals, brines, and salt deposits. They are also extracted from sea water and mountain ores.

Salts are necessary for the human body. Iron salts are needed to replenish hemoglobin, calcium - participate in the formation of the skeleton, magnesium - regulate the activity of the gastrointestinal tract.

Application of salts

Salts are actively used in production, everyday life, agriculture, medicine, food industry, chemical synthesis and analysis, and in laboratory practice. Here are just a few areas of their application:

- Sodium, potassium, calcium and ammonium nitrates (nitrate); calcium phosphate, Potassium chloride is a raw material for the production of fertilizers.
- Sodium chloride is necessary for the production of table salt; it is used in the chemical industry for the production of chlorine, soda, and caustic soda.
- Sodium hypochlorite is a popular bleach and water disinfectant.
- Salts of acetic acid (acetates) are used in the food industry as preservatives (potassium and calcium acetate); in medicine for the manufacture of drugs, in the cosmetics industry (sodium acetate), for many other purposes.
- Potassium-aluminum and potassium-chromium alums are in demand in medicine and the food industry; for dyeing fabrics, leather, furs.
- Many salts are used as fixatives to determine the chemical composition of substances, water quality, acidity level, etc.

Our store offers a wide range of salts, both organic and inorganic.

Salts- complex substances consisting of a metal atom or ammonium ion NH + 4 and an acid residue (sometimes containing hydrogen).

Practically all salts are ionic compounds, therefore, in salts, ions of acidic residues and metal ions are bound together

Salts are solid crystalline substances. Many substances have high melting and boiling points. Based on solubility, they are divided into soluble and insoluble.

A salt is the product of partial or complete substitution of a metal for the hydrogen atoms of an acid. Hence, the following types of salts are distinguished:

1. Medium salts– all hydrogen atoms in the acid are replaced by a metal: Na 2 CO 3, KNO 3, etc.
2. Acid salts– not all hydrogen atoms in the acid are replaced by a metal. Of course, acid salts can only form di- or polybasic acids. Monobasic acids cannot produce acidic salts: NaHCO 3, NaH 2 PO 4, etc. d.

3. Double salts– the hydrogen atoms of a di- or polybasic acid are replaced not by one metal, but by two different ones: NaKCO 3, KAl(SO 4) 2, etc.

4. Basic salts can be considered as products of incomplete, or partial, substitution of hydroxyl groups of bases with acidic residues: Al(OH)SO 4, Zn(OH)Cl, etc.

CLASSIFICATION OF SALT

Chemical properties

1. In aqueous solutions, salts can react with alkalis.

( magnesium chloride MgCl2 reacts with sodium hydroxide, forming a new salt and a new base: )

2. Salts can react with acids. So, a solution of barium nitrate

reacts with a solution of sulfuric acid, forming a new acid and

new salt:

H. In aqueous solutions, salts can react with each other.

If you pour together aqueous solutions of calcium chloride CaCl2 and sodium carbonate Na2CO3, TO a white precipitate of water-insoluble calcium carbonate CaCO3 is formed, and sodium chloride is formed in the solution:

4. In aqueous solutions of salts, the metal included in their composition can be replaced by another metal that comes before it in the activity series.

If a pure iron wire or a piece of zinc is dipped into a solution of copper sulfate, then copper is released on their surface, and iron sulfate (if iron was omitted) or zinc sulfate (if zinc was omitted) is formed in the solution:

Remember!!!

1. Salts react

with alkalis (if precipitation occurs or ammonia gas is released)

with acids stronger than the one that forms the salt

with other soluble salts (if precipitation occurs)

with metals (more active ones displace less active ones)

with halogens (more active halogens displace less active ones and sulfur)

2. Nitrates decompose with the release of oxygen:

if the metal is up to Mg, nitrite + oxygen is formed

if the metal is from Mg to Cu, metal oxide + NO2 + O2 is formed

if the metal comes after Cu, metal + NO2 + O2 is formed

Ammonium nitrate decomposes into N2O and H2O

3. Alkaline carbonates metals do not decompose when heated

4. Carbonates Group II metals decompose for metal oxide and carbon dioxide

Ticket 11. Hydrochloric acid (chloride acid). Chlorides. Chemical properties.

Ticket 18. Types of chemical bonds. Ionic and covalent. Examples.

What are salts?

Salts are complex substances that consist of metal atoms and acidic residues. In some cases, salts may contain hydrogen.

If we carefully examine this definition, we will notice that in their composition salts are somewhat similar to acids, the only difference being that acids consist of hydrogen atoms, and salts contain metal ions. It follows from this that salts are products of the replacement of hydrogen atoms in an acid with metal ions. So, for example, if we take the table salt NaCl, known to everyone, then it can be considered as a product of the replacement of hydrogen in hydrochloric acid HC1 with a sodium ion.

But there are also exceptions. Take, for example, ammonium salts; they contain acidic residues with an NH4+ particle, and not with metal atoms.

Types of salts

Now let's take a closer look at the classification of salts.

Classification:

Acid salts are those in which the hydrogen atoms in the acid are partially replaced by metal atoms. They can be obtained by neutralizing a base with excess acid.
Medium salts, or as they are also called normal salts, include those salts in which all hydrogen atoms in the acid molecules are replaced by metal atoms, for example, such as Na2CO3, KNO3, etc.
Basic salts include those in which the hydroxyl groups of bases are incompletely or partially replaced by acidic residues, such as Al(OH)SO4, Zn(OH)Cl, etc.
Double salts contain two different cations, which are obtained by crystallization from a mixed solution of salts with different cations, but the same anions.
But mixed salts include those that contain two different anions. There are also complex salts, which contain a complex cation or a complex anion.

Physical properties of salts

We already know that salts are solids, but you should know that they have different solubility in water.

If we consider salts from the point of view of solubility in water, they can be divided into groups such as:

Soluble (P),
- insoluble (N)
- sparingly soluble (M).

Nomenclature of salts

To determine the degree of solubility of salts, you can refer to the table of solubility of acids, bases and salts in water.

As a rule, all salt names consist of the names of an anion, which is presented in the nominative case, and a cation, which is in the genitive case.

For example: Na2SO4 - sodium sulfate (I.p.).

In addition, for metals, a variable oxidation state is indicated in parentheses.

Let's take for example:

FeSO4 - iron (II) sulfate.

You should also know that there is an international nomenclature for the name of the salts of each acid, depending on the Latin name of the element. For example, salts of sulfuric acid are called sulfates. For example, CaSO4 is called calcium sulfate. But chlorides are called salts of hydrochloric acid. For example, NaCl, which is familiar to all of us, is called sodium chloride.

If they are salts of dibasic acids, then the particle “bi” or “hydro” is added to their name.

For example: Mg(HCl3)2 – will sound like magnesium bicarbonate or bicarbonate.

If in a tribasic acid one of the hydrogen atoms is replaced by a metal, then the prefix “dihydro” should also be added and we get:

NaH2PO4 – sodium dihydrogen phosphate.

Chemical properties of salts

Now let's move on to considering the chemical properties of salts. The fact is that they are determined by the properties of the cations and anions that are part of them.

The importance of salt for the human body

There have long been discussions in society about the dangers and benefits of salt that it has on the human body. But no matter what point of view opponents adhere to, you should know that table salt is a natural mineral substance that is vital for our body.

You should also know that with a chronic lack of sodium chloride in the body, death can occur. After all, if we remember our biology lessons, we know that the human body is seventy percent water. And thanks to salt, the processes of regulating and maintaining water balance in our body occur. Therefore, it is impossible to exclude the use of salt under any circumstances. Of course, excessive consumption of salt will also not lead to anything good. And here the conclusion arises that everything should be in moderation, since its deficiency, as well as its excess, can lead to an imbalance in our diet.

Application of salts

Salts have found their use both for industrial purposes and in our daily lives. Now let's take a closer look and find out where and what salts are most often used.

Salts of hydrochloric acid

The most commonly used salts of this type are sodium chloride and potassium chloride. The table salt that we eat is obtained from sea and lake water, as well as from salt mines. And if we eat sodium chloride, then in industry it is used to produce chlorine and soda. But potassium chloride is indispensable in agriculture. It is used as potassium fertilizer.

Sulfuric acid salts

As for sulfuric acid salts, they are widely used in medicine and construction. It is used to make gypsum.

Nitric acid salts

Salts of nitric acid, or nitrates as they are also called, are used in agriculture as fertilizers. The most significant among these salts are sodium nitrate, potassium nitrate, calcium nitrate and ammonium nitrate. They are also called saltpeter.

Orthophosphates

Among orthophosphates, one of the most important is calcium orthophosphate. This salt forms the basis of minerals such as phosphorites and apatites, which are necessary in the manufacture of phosphate fertilizers.

Carbonic acid salts

Carbonic acid salts or calcium carbonate can be found in nature in the form of chalk, limestone and marble. It is used to make lime. But potassium carbonate is used as a component of raw materials in the production of glass and soap.

Of course, you know a lot of interesting things about salt, but there are also facts that you would hardly have guessed.

You probably know the fact that in Rus' it was customary to greet guests with bread and salt, but you were angry that they even paid a tax for salt.

Do you know that there were times when salt was more valuable than gold? In ancient times, Roman soldiers were even paid in salt. And the most dear and important guests were presented with a handful of salt as a sign of respect.

Did you know that the concept of “salary” comes from the English word salary.

It turns out that table salt can be used for medical purposes, as it is an excellent antiseptic and has wound-healing and bactericidal properties. After all, probably each of you has observed, while at sea, that wounds on the skin and calluses in salty sea water heal much faster.

Do you know why it is customary to sprinkle the paths with salt in winter when there is ice? It turns out that if salt is poured onto ice, the ice turns into water, since its crystallization temperature will decrease by 1-3 degrees.

Do you know how much salt a person consumes during the year? It turns out that in a year you and I eat about eight kilograms of salt.

It turns out that people living in hot countries need to consume four times more salt than those living in cold climates, because during the heat a large amount of sweat is released, and with it salts are removed from the body.

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 chlorine 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 interacts 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:

• 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.