Most ammonium salts are colorless crystalline solids that are readily soluble in water. In their structure, color and other properties, they are similar to the corresponding sodium or potassium salts, since Na +, K + and NH 4 + ions have similar sizes.

Chemical properties of ammonium salts

An aqueous solution of ammonia is a weak base, so ammonium salts are hydrolyzed in solutions. Solutions of salts formed by ammonia and strong acids have a slightly acidic reaction. The hydrolysis of the ammonium ion proceeds as follows:

NH 4 + + H 2 O ↔ NH 4 OH + H +

NH 4 + + H 2 O ↔ NH 3 + H 3 O +

The presence of an ammonium salt in a solution can be detected by heating the corresponding solution, and the salt decomposes - ammonia evaporates, as can be seen from the characteristic pungent odor.

Thermal decomposition of salts can proceed in two ways - reversible or irreversible. Ammonium salts, the anion of which is not an oxidizing agent or exhibits weak oxidizing properties, decompose reversibly. For example:

NH 4 Cl↔NH 3 + HCl

Ammonium salts, the anion of which exhibits more pronounced oxidizing properties, decompose irreversibly: OVR occurs, during which the ammonium ion is oxidized and the anion is reduced. For example:

NH 4 NO 3 \u003d N 2 O + 2 H 2 O

The interaction of ammonium salts with acids and other salts proceeds according to the exchange mechanism. For example:

(NH 4) 2 CO 3 + 2HCl → 2NH 4 Cl + H 2 O + CO 2

2NH 4 + + CO 3 2- + 2H + + 2Cl - → 2NH 4 + + 2Cl - + H 2 O + CO 2

CO 3 2− + 2H + → H 2 O + CO 2

(NH 4) 2 SO 4 + Ba(NO 3) 2 → BaSO 4 ↓ + 2NH 4 NO 3

2NH 4 + + SO 4 2− + Ba 2+ + 2NO 3 − → BaSO 4 ↓ + 2NH 4 + + 2NO 3 −

Ba 2+ + SO 4 2− → BaSO 4 ↓

A qualitative reaction to the ammonium ion is the reaction of the interaction of ammonium salts with alkalis when heated, resulting in the release of ammonia, which is determined by the characteristic pungent odor (the smell of "ammonia"):

NH 4 Cl + NaOH → NaCl + NH 3 + H 2 O

Key Representatives

The most important representatives of ammonium salts are sulfate, nitrate and ammonium chloride.

Ammonium sulfate ((NH 4) 2 SO 4) - colorless transparent crystals (or white powder) odorless. It is obtained by the action of sulfuric acid on an ammonia solution and by an exchange reaction between other salts:

Ammonium sulfate has found wide application as a mineral fertilizer, used in the production of viscose, in the food industry, etc.

Ammonium nitrate (NH 4 NO 3) is a white crystalline substance. On an industrial scale, ammonium nitrate is obtained by the action of concentrated nitric acid on anhydrous ammonia:

NH 3 + HNO 3 \u003d NH 4 NO 3

Ammonium nitrate is used as a mineral fertilizer - the nitrogen content in it is higher than in other fertilizers used. It forms explosive mixtures with combustible substances (ammonals), so it is used for blasting.

Ammonium chloride (ammonia) (NH 4 Cl) is a white, odorless crystalline powder. The main industrial method for obtaining ammonium chloride is the evaporation of the mother liquor remaining after the separation of sodium bicarbonate after the reaction in which carbon dioxide is passed through a solution of ammonia and sodium chloride:

NH 3 + H 2 O + CO 2 + NaCl \u003d NaHCO 3 + NH 4 Cl

Ammonium chloride is used in dyeing, calico printing, soldering and tinning, and also in galvanic cells.

Examples of problem solving

EXAMPLE 1

EXAMPLE 2

Exercise	Determine the amount of substance, volume (N.O.) and mass of ammonia required to obtain 250 g of ammonium sulfate used as a fertilizer.
Decision	Let's write the reaction equation: 2NH 3 + H 2 SO 4 \u003d (NH 4) 2 SO 4

ammonium salts

To The ammonium ion NH4+ plays the role of a metal cation and it forms salts with acid residues: NH4NO3 - ammonium nitrate, or ammonium nitrate, (NH4) 2SO4 - ammonium sulfate, etc.

All ammonium salts are solid crystalline substances, readily soluble in water. In a number of properties, they are similar to alkali metal salts, and primarily to potassium salts, since the radii of K+ and NH+ ions are approximately equal.

Ammonium salts are obtained by reacting ammonia or its aqueous solution with acids.

They have all the properties of salts due to the presence of acidic residues. For example, ammonium chloride or sulfate reacts with silver nitrate or barium chloride, respectively, to form characteristic precipitates. Ammonium carbonate reacts with acids as the reaction produces carbon dioxide.

In addition, the ammonium ion causes another property common to all ammonium salts: its salts react with alkalis when heated to release ammonia.

This reaction is a qualitative reaction for ammonium salts, since the resulting ammonia is easily detected (how exactly?).

The third group of properties of ammonium salts is their ability to decompose when heated with the release of gaseous ammonia, for example:

NH4Cl = NH3 + HCl

In this reaction, gaseous hydrogen chloride is also formed, which volatilizes along with ammonia, and when cooled, recombines with it, forming a salt, i.e., when heated in a test tube, dry ammonium chloride seems to sublime, but white crystals appear again on the upper cold walls of the test tube NH4Cl (Fig. 32).

The main areas of application of ammonium salts were shown earlier, in Figure 31. Here we draw your attention to the fact that almost all ammonium salts are used as nitrogen fertilizers. As you know, plants are able to assimilate nitrogen only in a bound form, i.e., in the form of NH4 or NO3 ions. The remarkable Russian agricultural chemist D. N. Pryanishnikov found out that if a plant has a choice, then it prefers the ammonium cation to the nitrate anion, so the use of ammonium salts as nitrogen fertilizers is especially effective. A very valuable nitrogen fertilizer is ammonium nitrate NH4NO3.

Let us note other areas of application of some ammonium salts.

Ammonium chloride NH4Cl is used in soldering, as it cleans the metal surface from the oxide film and solder adheres well to it.

Ammonium bicarbonate NH4NC03 and ammonium carbonate (NH4)2CO3 are used in confectionery, as they easily decompose when heated and form gases that loosen the dough and make it fluffy, for example:

NH4HC03 = NH3 + H20 + CO2

Ammonium nitrate NH4NO3 mixed with aluminum and coal powders is used as an explosive - ammonal, which is widely used in the development of rocks.

Saltpeter- natural nitrates - was known in China in the first centuries of our era; it was used to make gunpowder and hold fireworks. Later it is mentioned in writings (Latin names - nitro or sal nitri). By heating saltpeter with iron sulfate, alchemists received, which for a long time was called in Latin aqua fortis (“strong water”; in Russian texts, the term “ strong vodka»).

Pure nitric acid was first obtained by a German chemist Johann Rudolf Glauber acting on saltpeter with vitriol oil (concentrated):

KNO 3 + H 2 SO 4 \u003d KHSO 4 + HNO 3

Atacama Desert. Mining site for Chilean saltpeter

He also discovered that the interaction of nitric acid with potash K 2 CO 3 forms pure potassium nitrate. This discovery was of great practical importance, because earlier saltpeter, necessary for the production of gunpowder, was imported to Europe from the countries of the East, and also isolated from salt deposits on the walls of stables or from saltpeter pits, where it was formed under the action of microorganisms as the final product of the oxidation of nitrogen-containing organic compounds. .

When calcining a mixture of saltpeter NaNO 3, ferrous sulfate FeSO 4 ∙7H 2 O, potassium alum KAl (SO 4) 2 ∙12H 2 O and ammonia NH 4 Cl, alchemists managed to obtain a liquid that dissolved even the “king of metals” -. Therefore, it was called aqua regia, which means " royal water" or " aqua regia". Royal vodka is a yellow liquid formed by mixing three volumes and one volume of nitrogen. Even platinum dissolves easily in aqua regia.

Nitrogen was independently discovered at the end of the 18th century. several scientists. English explorer Henry Cavendish received "mephitic air" (as he called nitrogen), repeatedly passing air over hot coal (thereby removing oxygen), and then through a solution to absorb the formed.

Henry Cavendish

Compatriot of Cavendish Joseph Priestley described the formation of a gas that does not support combustion and respiration - "phlogistic air" - while observing the burning of a candle in a closed vessel.

Finally, another English scientist, Daniel Rutherford also received nitrogen from the air. Unlike Cavendish and Priestley, he immediately, in 1772, published a work where he described the production and properties of the "suffocating air" he had isolated. Therefore, it is Rutherford who is considered the discoverer of nitrogen.

In nature, the largest amount of nitrogen is in unbound form in the air. The main composition of atmospheric air was determined by A.L. Lavoisier, at whose suggestion the new element was called nitrogen. This name is composed of the Greek word "zoe" ("life") and the prefix "a" - ("non-") and means "lifeless", "not giving life." The Latin name for nitrogen is Nitrogenium, which translates as "forming nitrate."

Minerals that contain nitrogen are rare, for example, Chilean saltpeter NaNO 3, the deposits of which stretch along the coast of Chile and Peru for a distance of over 3600 km. At the end of the XIX century. its production was approximately 0.5 tons per year. It is no coincidence that entrepreneurs and scientists had fears that its reserves would soon run out. This prompted chemists to develop technologies for the binding of nitrogen in the air.

In industry, nitrogen is obtained from liquid air. To do this, the air is transferred to a liquid state, and at a temperature of - 196 0 C, nitrogen evaporates.

Nitrogen is produced in the laboratory decomposition of ammonium nitrite NH 4 NO 2 when heated:

NH 4 NO 2 \u003d N 2 + H 2 O

Physical Properties

A liquid nitrogen

Nitrogen- gas without color, taste and smell (t pl = -210 0 C, t bp = -196 0 C), slightly soluble in water. Free nitrogen is chemically inert due to its high strength molecules N 2 where the atoms are triple bonded. Therefore, nitrogen hardly enters into chemical reactions, does not support combustion and respiration.

Characteristic oxidation states:

— 3 0 +1 +2 +3 +4 +5

NH 3 N 2 N 2 O NO N 2 O 3 NO 2 N 2 O 5

Chemical properties

In chemical reactions, nitrogen can be both an oxidizing agent and a reducing agent.

Nitrogen interacts as an oxidizing agent:

N 2 + 3Ca \u003d Ca 3 N 2

Nitrogen interacts as a reducing agent:

N 2 + F 2 \u003d 2NF 3

Application

Nitrogen is the feedstock for the production of ammonia.

Ammonia

Ammonia- a colorless gas with a pungent odor, highly soluble in water. In one liter of water at a temperature of 20 0 C, 700 liters of ammonia dissolve. This solution is called ammonia water or ammonia.

Chemical properties

Acid-base properties

The nitrogen atom in the ammonia molecule has an unshared electron pair, which can participate in the formation of a donor-acceptor bond. In particular, the nitrogen atom in NH 3 is able to attach the hydrogen ion H + . Substances whose molecules are capable of attaching hydrogen ions have basic properties. Therefore, ammonia has the main properties:

• interaction of ammonia with water:

NH 3 + HOH ⇄ NH 4 OH ⇄ NH 4 + + OH -

• interaction with hydrogen halides:

NH 3 + HCl ⇄ NH 4 Cl

• interaction with (as a result, medium and acidic salts are formed):

NH 3 + H 3 PO 4 = (NH 4) 3 PO 4; (NH 4) 2 HPO 4 ; (NH 4) H 2 PO 4

• ammonia interacts with some metals to form complex compounds - ammoniates:

CuSO 4 + 4NH 3 \u003d SO 4 Copper (II) tetraammine sulfate

AgCl + 2NH 3 \u003d Cl Silver (I) diamine chloride

Redox properties

In the ammonia molecule, nitrogen has an oxidation state of 3, therefore, in redox reactions, it can only donate electrons and is only a reducing agent.

• ammonia restores some of them:

2NH 3 + 3CuO = N 2 + 3Cu + 3H 2 O

• ammonia is oxidized without a catalyst to nitrogen:

4NH 3 + 3O 2 \u003d 2N 2 + 6H 2 O

• ammonia in the presence of a catalyst is oxidized to nitrogen monoxide NO:

4NH 3 + 5O 2 \u003d 4NO + 6H 2 O

ammonium salts

ammonium chloride

When ammonia or ammonium hydroxide reacts with ammonium salts:

All ammonium salts are highly soluble in water. Ammonium salts have The special properties of ammonium salts include the reactions of their thermal decomposition, which proceed differently, depending on the nature of the anion, for example:

(NH 4) 2 SO 4 \u003d NH 3 + NH 4 HSO 4

NH 4 NO 3 \u003d N 2 O + 2H 2 O

NH 4 Cl \u003d NH 3 + HCl

The reaction of interaction of ammonium salts is qualitative reaction to the ammonium cationNH 4 + :

NH 4 Cl + NaOH = NaCl + NH 3 + H 2 O

NH 4 + + OH - = NH 3 + H 2 O

The released ammonia is determined by the smell or by the blue color of wet litmus paper.

The use of ammonia and ammonium salts

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Ammonium is one of the many nitrogen compounds. Its salts have a number of interesting properties and find practical application in many areas of human activity. Chemistry is the study of the properties of this element. Ammonium salts are studied in the section on the interaction of nitrogen with other chemical elements.

What is ammonium

To find out what ammonium is, you should take a closer look at the principle of combining nitrogen and carbon atoms. The ammonia molecule is written as NH 3. The nitrogen atom is bound by its covalent bonds with three protons. Due to the internal structure of the nitrogen, one bond remains undistributed.

Therefore, NH 3 actively enters into various covalent bonds with other elements, using an undistributed electron pair. If a hydrogen nucleus enters the compound, an ammonium ion is formed. The reaction scheme is shown below:

As can be seen, in this reaction, the ammonia molecule is an acceptor of one proton and thus behaves like a base. Ammonium does not exist in its free form, as it almost instantly decomposes into hydrogen and ammonia. Ammonium salts are obtained as a result of the interaction of this element with other substances. As practical experiments show, ammonium enters into various compounds with acids, neutralizing them and forming ammonium salts. For example, in the case of reaction with hydrochloric acid, one of the salts of this element is formed:

NH 3 + HCl = NH 4 Cl

As a result of the reaction, ammonium salt chloride is obtained.

Interaction with water

Ammonium interacts well with water. As a result of the reaction, ammonia hydrates are obtained with an increased concentration of OH - . Chemical record of the reaction:

NH 3 + H 2 O → NH 4 + OH -

Since the number of hydroxo group ions is extremely large, aqueous solutions of ammonia have an alkaline reaction. However, according to the old chemical habit, an aqueous solution of ammonia is written as NH 4 OH. This substance is called ammonium hydroxide, and the alkaline reaction of this compound is considered in the form of dissociation of molecules into which ammonia is decomposed.

Ammonium salts. Properties and main characteristics

Most of the NH 4 salts are practically colorless and quite soluble in water. This compound has many properties of metals, therefore ammonium salts behave in the same way as salts of various metals. Here are some examples of such similarity:

NH 4 salts are good electrolytes. They undergo hydrolysis in various solutions. This reaction can be traced on the example of the dissociation of ammonium chloride:

NH 4 Cl \u003d NH 4 + + HCl -

subject to hydrolysis. The result is the reaction of a salt of a weak base and a strong acid:

They have an ionic crystal lattice, have electrical conductivity;

They do not withstand high temperatures and break down into components.

Irreversible and reversible processes

The decomposition of ammonium salts under the influence of temperatures can be irreversible, or it can be a reversible process. If the salt anion exhibits mild oxidizing properties, the salt decomposes reversibly. A classic example of such a reaction is ammonium chloride: when the reaction temperature rises, it eventually decomposes into its own starting elements - hydrogen chloride, as well as ammonia. If the walls of the vessel are not heated, plaque appears on them. This is how ammonium chloride is generated.

Other salts of this element, in which the anion has pronounced oxidizing properties, decompose irrevocably. A standard example of such a reaction is the decomposition of ammonium nitrate, which looks like this:

NH 4 NO 3 \u003d N 2 O + H 2 O

Since one of the interaction products leaves its field, the reaction stops.

The use of ammonia and ammonium salts

A significant proportion of industrially produced ammonia is used in freezing and refrigeration plants. Ammonium salts are used in everyday life and in medicine. But the vast majority of ammonia is used to produce nitric acid and various nitrogen-containing compounds, primarily various mineral fertilizers.

Nitrogen fertilizers

The most famous nitrogen derivative salts, the use of which is extremely important in economic activities, are ammonium sulfate, ammonium nitrate, ammonium chloride. Nitrogen is an essential component of proteins. This element is essential for the existence of any living organism. Plants extract nitrogen from fertile soil, where this element is found predominantly in a bound form. Nitrogen usually occurs as ammonium salts and nitric acid compounds. Dissolving in moist soil, these inorganic compounds enter the organisms of plants and are processed by them into various proteins and amino acids. Animals and humans cannot assimilate nitrogen either in its free form or as its simple compounds. For nutrition and growth, they need protein, an integral part of which is necessarily nitrogen. Only with the participation of plants we get the element so necessary for us for life and health.

Soils in the natural environment contain a small amount of nitrogen. After the harvest of each crop, along with the plants, the small amount of nitrogen that was previously in the ground is carried away. To speed up the process of soil regeneration, nitrogenous fertilizers are used.

Ammonium sulfate. The formula of this compound is (NH4) 2 SO 4. This ammonium salt serves as the basis for many fertilizers.

ammonium nitrate. The formula of this substance is NH 4 NO 3. It is also a well-known fertilizer that is well absorbed by plants. In addition to agricultural use, ammonium nitrate is used in the military and mining industries - explosive mixtures (ammonals) used for demolition work are made on its basis.

ammonium chloride

ammonium chloride. Well known as ammonia. Its chemical formula is NH 4 Cl. This compound is well known in the production of paint and varnish products, in the textile business, ammonia is used and in galvanic cells. Ammonium chloride is well known to shareholders and tinkers. In their work, they often use ammonium chloride salts. The use of this substance helps to remove the thinnest oxide films from the surface of metals. The touch of a heated metal to ammonia causes a corresponding reaction of oxides - they either turn into chlorides or are reduced. Chlorides quickly evaporate from the metal surface. The reaction process for copper can be written as follows:

4CuO + 2NH 4 Cl \u003d 3Cu + 2CuCl 2 + N 2 + 4H 2 O.

Ammonia in liquid form and strong solutions of ammonium salts are also used as nitrogen fertilizers - the nitrogen content in them is higher than in solid fertilizers, and it is better absorbed by plants.

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Ammonium salts - salts containing a positively charged ammonium ion NH4 +; in structure, color and other properties, they are similar to the corresponding potassium salts. All ammonium salts are soluble in water and completely dissociate in aqueous solution. Ammonium salts exhibit the general properties of salts. Under the action of alkali, gaseous ammonia is released. All ammonium salts decompose when heated. They are obtained by reacting NH3 or NH4OH with acids.

Application

Ammonium nitrate (ammonium nitrate) NH4NO3 is used as a nitrogen fertilizer and for the manufacture of explosives - ammonites;

Ammonium sulfate (NH4)2SO4 - as a cheap nitrogen fertilizer;

Ammonium bicarbonate NH4HCO3 and ammonium carbonate (NH4)2CO3 - in the food industry in the production of flour confectionery products as a chemical baking powder, in dyeing fabrics, in the production of vitamins, in medicine;

Ammonium chloride (ammonia) NH4Cl - in galvanic cells (dry batteries), in soldering and tinning, in the textile industry, as a fertilizer, in veterinary medicine.

Chemical properties of salts

Strong electrolytes (dissociate in aqueous solutions):

NH4Cl ↔ NH4+ + Cl−

Decomposition on heating:

a) if the acid is volatile

NH4Cl → NH3 + HCl

NH4HCO3 → NH3 + H2O + CO2

b) if the anion exhibits oxidizing properties

NH4NO3 → N2O + 2Н2O

(NH4)2Cr2O7 → N2 + Cr2O3+ 4Н2O

With acids (exchange reaction):

(NH4)2CO3 + 2HCl → 2NH4Cl + H2O + CO2

2NH4+ + CO32− + 2H+ + 2Cl− → 2NH4+ + 2Cl− + Н2O + CO2

CO32− + 2H+ → Н2O + CO2

With salts (exchange reaction):

(NH4)2SO4 + Ba(NO3)2 → BaSO4 ↓ + 2NH4NO3

2NH4+ + SO42− + Ba2+ + 2NO3− → BaSO4 ↓ + 2NH4+ + 2NO3−

Ba2+ + SO42− → BaSO4 ↓

Ammonium salts undergo hydrolysis (as a salt of a weak base and a strong acid) - an acidic environment:

NH4Cl + H2O ↔ NH4OH + HCl

NH4+ + H2O ↔ NH4OH + H+

When heated with alkalis, ammonia is released (qualitative reaction to the ammonium ion)

NH4Cl + NaOH → NaCl + NH3 + H2O

Iron deficiency anemia (IDA) is a hematological syndrome characterized by impaired hemoglobin synthesis due to iron deficiency and manifested by anemia and sideropenia. The main causes of IDA are blood loss and lack of heme-rich food - meat and fish.

Treatment is carried out only by long-term intake of ferrous iron preparations inside in moderate doses, and a significant increase in hemoglobin, in contrast to improving well-being, will not be fast - after 4-6 weeks.

Usually, any ferrous preparation is prescribed - more often it is ferrous sulfate - its prolonged dosage form is better, at an average therapeutic dose for several months, then the dose is reduced to the minimum for a few more months, and then (if the cause of anemia has not been eliminated), the maintenance minimum is continued. doses over a week monthly for many years. So, this practice has justified itself well in the treatment of women with chronic posthemorrhagic iron deficiency anemia due to long-term hyperpolymenorrhea with tardiferron - one tablet in the morning and evening for 6 months without a break, then one tablet a day for another 6 months, then for several years every day for a week on menstruation days . This disciplines patients, does not allow them to forget the timing of taking the drug and provides an iron load when prolonged heavy periods appear during menopause. A meaningless anachronism is to determine the level of hemoglobin before and after menstruation.