Chemical name for ammonia. Ammonia use

Ammonia -NH 3

Ammonia (in European languages ​​its name sounds like "ammoniac") owes its name to the oasis of Ammon in North Africa, located at the crossroads of caravan routes. In hot climates, urea (NH 2) 2 CO contained in animal waste decomposes especially quickly. One of the degradation products is ammonia. According to other sources, ammonia got its name from the ancient Egyptian word amonian. So called people worshiping the god Amun. During their ritual rites, they sniffed ammonia NH 4 Cl, which, when heated, evaporates ammonia.

1. The structure of the molecule

The ammonia molecule has the shape of a trigonal pyramid with a nitrogen atom at the top. Three unpaired p-electrons of the nitrogen atom participate in the formation of polar covalent bonds with 1s-electrons of three hydrogen atoms (N-H bonds), the fourth pair of external electrons is unshared, it can form a donor-acceptor bond with a hydrogen ion, forming an ammonium ion NH 4 + .

Type of chemical bond:covalent polar, three singleσ - N-H bond sigma

2. Physical properties of ammonia

Under normal conditions, it is a colorless gas with a pungent characteristic odor (the smell of ammonia), almost twice as light as air, poisonous.According to the physiological effect on the body, it belongs to the group of substances with an asphyxiant and neurotropic effect, which, when inhaled, can cause toxic pulmonary edema and severe damage to the nervous system. Ammonia vapor strongly irritates the mucous membranes of the eyes and respiratory organs, as well as the skin. This is what we perceive as a pungent smell. Ammonia vapors cause profuse lacrimation, pain in the eyes, chemical burns of the conjunctiva and cornea, loss of vision, coughing fits, redness and itching of the skin. The solubility of NH 3 in water is extremely high - about 1200 volumes (at 0 °C) or 700 volumes (at 20 °C) in a volume of water.

3.

4. Chemical properties of ammonia

For ammonia, reactions are characteristic:

1. with a change in the oxidation state of the nitrogen atom (oxidation reactions)
2. without changing the oxidation state of the nitrogen atom (addition)

5. Application of ammonia

In terms of production volumes, ammonia occupies one of the first places; annually around the world receive about 100 million tons of this compound. Ammonia is available in liquid form or as an aqueous solution - ammonia water, which usually contains 25% NH 3 . Huge amounts of ammonia are further used to produce nitric acid which goes to fertilizer production and many other products. Ammonia water is also used directly as a fertilizer, and sometimes the fields are watered from tanks directly with liquid ammonia. From ammonia receive various ammonium salts, urea, urotropin. His also used as a cheap refrigerant in industrial refrigeration systems.

Ammonia is also used for the production of synthetic fibers, for example, nylon and capron. In light industry, used in cleaning and dyeing cotton, wool and silk. In the petrochemical industry, ammonia is used to neutralize acidic wastes, and in the natural rubber industry, ammonia helps preserve the latex during its transportation from the plantation to the factory. Ammonia is also used in the production of soda using the Solvay method. In the steel industry, ammonia is used for nitriding - saturation of the surface layers of steel with nitrogen, which significantly increases its hardness.

Doctors use aqueous solutions of ammonia (ammonia) in everyday practice: a cotton swab dipped in ammonia brings a person out of a faint. For humans, ammonia in such a dose is not dangerous.

SIMULATORS

Simulator №1 "Combustion of ammonia"

Simulator №2 "Chemical properties of ammonia"

TASKS FOR REINFORCEMENT

№1. Carry out transformations according to the scheme:

a) Nitrogen → Ammonia → Nitric oxide (II)

b) Ammonium nitrate → Ammonia → Nitrogen

c) Ammonia → Ammonium chloride → Ammonia → Ammonium sulfate

And hydrogen. It is a colorless gas, but with a pungent odor. The chemical composition reflects the formula of ammonia - NH 3. An increase in pressure or a decrease in the temperature of a substance leads to its transformation into a colorless liquid. Gaseous ammonia and its solutions are widely used in industry and agriculture. In medicine, 10% ammonium hydroxide is used - ammonia.

The structure of the molecule. Electronic formula of ammonia

The hydrogen nitride molecule is shaped like a pyramid, at the base of which is nitrogen bonded to three hydrogen atoms. The N–H bonds are highly polarized. Nitrogen attracts the bonding electron pair more strongly. Therefore, the negative charge is accumulated on the N atoms, while the positive charge is concentrated on the hydrogen. An idea of ​​this process is given by the model of the molecule, electronic and ammonia.

Hydrogen nitride is very soluble in water (700:1 at 20°C). The presence of practically free protons leads to the formation of numerous hydrogen "bridges" that connect the molecules to each other. Structural features and chemical bonding also lead to the fact that ammonia is easily liquefied with an increase in pressure or a decrease in temperature (-33 ° C).

origin of name

The term "ammonia" was introduced into scientific use in 1801 at the suggestion of the Russian chemist Y. Zakharov, but the substance has been known to mankind since ancient times. A gas with a pungent odor is released during the decay of waste products, many organic compounds, such as proteins and urea, during the decomposition of ammonium salts. Historians of chemistry believe that the substance was named after the ancient Egyptian god Amun. The oasis of Siwa (Ammon) is located in North Africa. Surrounded by the ruins of an ancient city and a temple, next to which there are deposits of ammonium chloride. This substance in Europe was called the "salt of Amon." There is a legend that the inhabitants of the Siwa oasis sniffed salt in the temple.

Obtaining hydrogen nitride

The English physicist and chemist R. Boyle burned manure in experiments and observed the formation of white smoke over a stick dipped in hydrochloric acid and introduced into the stream of the resulting gas. In 1774, another British chemist, D. Priestley, heated ammonium chloride with slaked lime and isolated a gaseous substance. Priestley called the compound "alkaline air", because its solution exhibited properties. Boyle's experiment, in which ammonia interacted with hydrochloric acid, was explained. A solid white color occurs when the molecules of the reactants come into contact directly in the air.

The chemical formula of ammonia was established in 1875 by the Frenchman C. Berthollet, who conducted an experiment on the decomposition of a substance into its constituent components under the influence of an electric discharge. Until now, the experiments of Priestley, Boyle and Berthollet are being reproduced in laboratories to obtain hydrogen nitride and ammonium chloride. The industrial method was developed in 1901 by A. Le Chatelier, who received a patent for a method for synthesizing a substance from nitrogen and hydrogen.

Ammonia solution. Formula and properties

An aqueous solution of ammonia is usually written as hydroxide - NH 4 OH. It exhibits the properties of a weak alkali:

• dissociates into ions NH 3 + H 2 O \u003d NH 4 OH \u003d NH 4 + + OH -;
• colors the solution of phenolphthalein in crimson color;
• reacts with acids to form salt and water;
• precipitates Cu(OH) 2 as a bright blue substance when mixed with soluble copper salts.

The equilibrium in the reaction of the interaction of ammonia with water is shifted towards the starting materials. Preheated hydrogen nitride burns well in oxygen. Nitrogen is oxidized to diatomic molecules of the simple substance N2. Ammonia also exhibits reducing properties in reaction with copper (II) oxide.

The value of ammonia and its solutions

Hydrogen nitride is used in the production of ammonium salts and nitric acid, one of the most important products of the chemical industry. Ammonia serves as a raw material for the production of soda (according to the nitrate method). The content of hydrogen nitride in an industrial concentrated solution reaches 25%. In agriculture, an aqueous solution of ammonia is used. The liquid fertilizer formula is NH 4 OH. The substance is directly used as a top dressing. Other ways to enrich the soil with nitrogen are the use of salts of chlorides, phosphates. In industrial conditions and agricultural premises, it is not recommended to store mineral fertilizers containing ammonium salts together with alkalis. If the integrity of the packaging is violated, the substances can react with each other with the formation of ammonia and its release into the indoor air. A toxic compound adversely affects the respiratory system, the human central nervous system. The mixture of ammonia with air is explosive.

Properties of ammonia NH 3 (gas) at atmospheric pressure

Ammonia (NH 3) is a toxic combustible gaseous substance that has the ability to form an explosive mixture upon contact with air.

It exists as a gas at normal pressure and room temperature. For use in production and transportation, ammonia (nitride) is liquefied.

Technical ammonia is used as the main raw material in the production of a large number of substances containing and used in various industries: mineral fertilizers, hydrocyanic acids, in general organic synthesis, etc.

The table shows the density and thermophysical properties of ammonia in the gaseous state, depending on the temperature at a pressure of 760 mm Hg. The properties of ammonia are indicated at temperatures from -23 to 627 ° C.

The table gives the following properties of ammonia:

• ammonia density, kg/m 3 ;
• thermal conductivity coefficient, W/(m deg);
• dynamic viscosity, ;
• Prandtl number.

According to the table, it can be seen that the properties of ammonia significantly depend on temperature. So, with increasing temperature, the density of ammonia decreases, and the Prandtl number; other characteristics of this gas increase their values.

For example, at a temperature 27°С(300 K) ammonia has a density equal to 0.715 kg / m 3, and when heated to 627 ° C (900 K), the density of ammonia decreases to a value of 0.233 kg / m 3.

The density of ammonia at room temperature and normal atmospheric pressure is substantially lower under these conditions.

Note: Be careful! The thermal conductivity of ammonia in the table is indicated in the degree of 10 3. Don't forget to divide by 1000.

Properties of ammonia (dry saturated steam)

The table gives the thermophysical properties of dry saturated ammonia depending on temperature.
Properties are given in the temperature range from -70 to 70 °C.

The table shows the following properties of ammonia vapor:

• ammonia density, kg/m 3 ;
• heat of phase transition, kJ/kg;
• specific heat capacity, kJ/(kg deg);
• thermal diffusivity, m 2 /s;
• dynamic viscosity, Pa s;
• kinematic viscosity, m 2 /s;
• Prandtl number.

The properties of ammonia are highly dependent on temperature. There is a direct relationship between the temperature and pressure of saturated vapors of ammonia.
In this case, the density of saturated ammonia vapor increases significantly. The values ​​of thermal diffusivity and viscosity decrease. The thermal conductivity of saturated ammonia vapor in the table is given to the power of 10 4 . Don't forget to divide by 10000.

Properties of liquid ammonia in saturation state

The table shows the thermophysical properties of saturated ammonia liquid depending on the temperature.
The properties of ammonia in a saturated liquid state are given in the temperature range from -70 to 70 °C.

The table shows the following properties of liquid ammonia:

• saturated vapor pressure, MPa;
• ammonia density, kg/m 3 ;
• specific heat capacity, kJ/(kg deg);
• thermal conductivity, W/(m deg);
• thermal diffusivity, m 2 /s;
• dynamic viscosity, Pa s;
• kinematic viscosity, m 2 /s;
• surface tension coefficient, N/m;
• Prandtl number.

The density of ammonia in the liquid state is less dependent on temperature than the density of its vapor. Only the dynamic viscosity decreases significantly with an increase in the temperature of liquid ammonia.

Thermal conductivity of ammonia in liquid and gaseous states

The table shows the thermal conductivity values ​​of ammonia in liquid and gaseous states depending on temperature and pressure.
The thermal conductivity of ammonia (dimension W / (m deg)) is indicated in the temperature range from 27 to 327 ° C and pressure from 1 to 1000 atmospheres.

The thermal conductivity of ammonia in the table is indicated in the degree of 10 3. Don't forget to divide by 1000.
Thermal conductivity values ​​above the line are indicated for liquid ammonia, the thermal conductivity of which decreases with increasing temperature.

The thermal conductivity of gaseous ammonia increases when heated. An increase in pressure leads to an increase in the thermal conductivity for both liquid and gaseous ammonia.

The following table shows thermal conductivity of ammonia at low temperatures and atmospheric pressure.

on the saturation line depending on the temperature is given in the table below. It should be noted that the thermal conductivity of liquid ammonia decreases when heated.

Note: Be careful! The thermal conductivity of ammonia in the tables is given to the power of 10 3 . Don't forget to divide by 1000.

A number of factors influence the process of producing the optimal amount of a chemical, as well as achieving its maximum quality. The production of ammonia depends on pressure, temperature, the presence of a catalyst, the substances used and the method of extracting the obtained material. These parameters must be properly balanced to achieve the greatest profit from the production process.

Properties of ammonia

At room temperature and normal air humidity, ammonia is in a gaseous state and has a very repulsive odor. It is endowed with a poisonous and irritating mucous membrane effect on the body. The production and properties of ammonia depend on the participation of water in the process, since this substance is very soluble in normal environmental conditions.

Ammonia is a compound of hydrogen and nitrogen. Its chemical formula is NH 3 .

This chemical substance acts as an active reducing agent, as a result of which free nitrogen is released as a result of combustion. Ammonia exhibits the characteristics of bases and alkalis.

The reaction of a substance with water

When NH 3 is dissolved in water, ammonia water is obtained. Maximum at normal temperature, 700 volumes of ammonia can be dissolved in 1 volume of a water element. This substance is known as ammonia and is widely used in the fertilizer industry, in technological installations.

NH 3 obtained by dissolving in water is partially ionized in its qualities.

Ammonia is used in one of the laboratory methods for obtaining this element.

Obtaining a substance in the laboratory

The first method for obtaining ammonia is to bring ammonia to a boil, after which the resulting vapor is dried and the required chemical compound is collected. Obtaining ammonia in the laboratory is also possible by heating slaked lime and solid ammonium chloride.

The reaction for obtaining ammonia is as follows:

2NH 4 Cl + Ca(OH) 2 → CaCl 2 + 2NH 3 + 2H 2 O

During this reaction, a white precipitate is formed. This is CaCl 2 salt, and water and the desired ammonia are also formed. To carry out the drying of the required substance, it is passed through a mixture of lime in combination with soda.

Obtaining ammonia in the laboratory does not provide the most optimal technology for its production in the required quantities. For many years, people have been looking for ways to extract the substance on an industrial scale.

The origins of the establishment of production technologies

During the years 1775-1780, experiments were carried out to bind free nitrogen molecules from the atmosphere. The Swedish chemist K. Shelle found a reaction that looked like

Na 2 CO 3 + 4C + N 2 \u003d 2NaCN + 3CO

On its basis, in 1895, N. Caro and A. Frank developed a method for binding free nitrogen molecules:

CaC 2 + N 2 \u003d CaCN 2 + C

This option required a lot of energy and was not economically viable, so over time it was abandoned.

Another rather costly method was the process of interaction between nitrogen and oxygen molecules discovered by the English chemists D. Priestley and G. Cavendish:

Growing demand for ammonia

In 1870, this chemical was considered an undesirable product of the gas industry and was practically useless. However, after 30 years, it has become very popular in the coke industry.

At first, the increased need for ammonia was replenished by isolating it from coal. But with a 10-fold increase in the consumption of the substance, practical work was carried out to find ways to extract it. The production of ammonia began to be introduced using reserves of atmospheric nitrogen.

The need for nitrogen-based substances was observed in almost all known sectors of the economy.

Finding ways to meet industrial demand

Mankind has come a long way to implement the equation for the production of matter:

N 2 + 3H 2 \u003d 2NH 3

The production of ammonia in industry was first realized in 1913 by catalytic synthesis from hydrogen and nitrogen. The method was discovered by F. Gaber in 1908.

The open technology has solved a long-standing problem of many scientists from different countries. Up to this point, it was not possible to bind nitrogen in the form of NH 3 . This chemical process is called the cyanamide reaction. When the temperature of lime and carbon was increased, the substance CaC 2 (calcium carbide) was obtained. By heating nitrogen, calcium cyanamide CaCN 2 was obtained, from which ammonia was released by hydrolysis.

Implementation of technologies for ammonia production

Obtaining NH 3 on a global scale for industrial consumption began with the purchase of a patent for F. Haber technologies by A. Mittasch, a representative of the Baden soda plant. At the beginning of 1911, the synthesis of ammonia in a small plant became regular. K. Bosch created a large contact apparatus based on the developments of F. Haber. It was the original equipment providing the ammonia recovery process by synthesis on a production scale. K. Bosch took over all the leadership on this issue.

Saving energy costs involved the participation of certain catalysts in the synthesis reactions.

A group of scientists working on the search for suitable components proposed the following: an iron catalyst, to which oxides of potassium and aluminum were added, and which is still considered one of the best providing ammonia in the industry.

On September 9, 1913, the world's first plant using catalytic synthesis technology began its work. Production capacities were gradually increased, and by the end of 1917, 7 thousand tons of ammonia were produced per month. In the first year of operation of the plant, this figure was only 300 tons per month.

Subsequently, all other countries also began to use the synthesis technology using catalysts, which in essence did not differ much from the Haber-Bosch technique. The use of high pressure and circulation processes occurred in any technological process.

Implementation of synthesis in Russia

In Russia, synthesis was also used using catalysts that provide ammonia production. The reaction looks like this:

In Russia, the very first ammonia synthesis plant began its work in 1928 in Chernorechensk, and then production facilities were built in many other cities.

Practical work on obtaining ammonia is constantly gaining momentum. Between 1960 and 1970, synthesis increased by almost 7 times.

In the country, for the successful production, collection and recognition of ammonia, mixed catalytic substances are used. The study of their composition is carried out by a group of scientists led by S. S. Lachinov. It was this group that found the most effective materials for the synthesis technology.

The kinetics of the process is also constantly being studied. Scientific developments in this area were carried out by M. I. Temkin, as well as his employees. In 1938, this scientist, together with his colleague V. M. Pyzhev, made an important discovery, improving the production of ammonia. The equation for the kinetics of synthesis, compiled by these chemists, is now used throughout the world.

Modern synthesis process

The process of obtaining ammonia using a catalyst, used in today's production, is reversible. Therefore, the question of the optimal level of the impact of indicators on achieving the maximum yield of products is very relevant.

The process takes place at a high temperature: 400-500 ˚С. A catalyst is used to ensure the required reaction rate. Modern production of NH 3 involves the use of high pressure - about 100-300 atm.

Together with the use of a circulating system, it is possible to obtain a sufficiently large mass of initial materials converted into ammonia.

Modern production

The operation system of any ammonia plant is quite complex and includes several stages. The technology for obtaining the desired substance is carried out in 6 stages. During the synthesis, ammonia is obtained, collected and recognized.

The initial stage consists in the extraction of sulfur from natural gas using a desulfurizer. This manipulation is required due to the fact that sulfur is a catalytic poison and kills the nickel catalyst at the stage of hydrogen extraction.

The second stage is the conversion of methane, which proceeds with the use of high temperature and pressure using a nickel catalyst.

At the third stage, partial burnout of hydrogen in atmospheric oxygen occurs. As a result, a mixture of water vapor, carbon monoxide, and nitrogen is produced.

The fourth step is the shift reaction, which takes place with different catalysts and two different temperature conditions. Initially, Fe 3 O 4 is used, and the process proceeds at a temperature of 400 ˚С. In the second stage, a more efficient copper catalyst is involved, which allows production at low temperatures.

The next fifth stage involves the removal of unnecessary carbon monoxide (VI) from the gas mixture by applying the technology of absorption with an alkali solution.

At the final stage, carbon monoxide (II) is removed using the reaction of hydrogen conversion into methane through a nickel catalyst and a high temperature.

The gas mixture obtained as a result of all manipulations contains 75% hydrogen and 25% nitrogen. It is compressed under high pressure and then cooled.

It is these manipulations that are described by the ammonia release formula:

N 2 + 3H 2 ↔ 2 NH 3 + 45.9 kJ

Although this process does not look very complicated, however, all of the above steps for its implementation indicate the complexity of obtaining ammonia on an industrial scale.

The quality of the final product is affected by the absence of impurities in the raw material.

Having gone a long way from a small laboratory experience to large-scale production, ammonia production today is a sought-after and indispensable branch of the chemical industry. This process is constantly being improved, ensuring the quality, economy and the required amount of product for each cell of the national economy.

The use of anhydrous liquefied ammonia

Anhydrous liquefied ammonia (hydrogen nitrite) is a colorless transparent liquid. It is toxic and has good solubility in water.

Ammonia is produced by the catalytic synthesis of nitrogen and hydrogen. It has toxic properties, can cause burns, according to GOST 6221-90 has IV hazard class.

Hydrogen nitrite is a slow-burning substance, but when mixed with air it is explosive, especially in enclosed spaces.

Also, explosive mixtures can be formed by the interaction of hydrogen nitrite with calcium, bromine, silver oxide, chlorine, iodine, mercury and some other elements.

Contact of ammonia with mercury, chlorine, iodine, bromine, calcium, silver oxide and some other chemicals can lead to the formation of explosive compounds.

Hydrogen nitrite is characterized by corrosive functions:

Contact with zinc, copper (accelerates in the presence of water); rubber dissolution; various types of steel are susceptible to cracking in the presence of oxygen if their composition of water is less than 0.2%.

Applications of ammonia:

Fertilizers (urea, ammonium nitrate, complex fertilizers), nitric acid and other nitrogen-containing compounds are made from it.

When these fertilizers are applied in the required amount, crop yields can significantly increase (from 8 to 60%).

The advantages of its use are:

Cheapness; efficiency; the possibility of fertilizing in the fall, for the next harvest; mechanization of the processes of delivery and application of fertilizers to the soil. Refrigeration industry.

Ammonia is used as a refrigerant. Currently, the refrigeration industry is being modernized, new schemes are being developed, ways are being sought to reduce the ammonia capacity of existing plants.

Systems for automatic control and protection of all refrigeration equipment are being designed, and ways are being found to reduce harmful emissions in the event of depressurization of refrigeration devices.

Most often used to create protective environments (atmospheres). .

Nitric acid, made from hydrogen nitrite, is used to create dyes, artificial fibers, explosives, and plastics.

In medicine, ammonia is widely used, consisting of 10% ammonia.

Ammonia is given to smell in fainting and semi-conscious state. With its help, headaches, nausea and other signs characteristic of a state of severe alcohol intoxication are removed. Rubbing insect bites relieves discomfort and itching. Gen.

At home, ammonia is also used to clean windows, silver and nickel-plated dishes. That's how it is =)..