What is ammonia? Formula and properties of ammonia

Ammonia is a compound that is the most important source of nitrogen for living organisms, and has also found application in various industries. What is ammonia, what are its properties? Let's figure it out.

What is ammonia: the main characteristics

Ammonia (water conduit nitride) is a compound of nitrogen with hydrogen, having the chemical formula NH ₃ . The shape of the molecule resembles a trigonal pyramid with the nitrogen atom at its apex.

Ammonia is a gas that does not have a color, but has a sharp specific smell. The density of ammonia is almost half that of air. At a temperature of 15 ^° C, it is 0.73 kg / m ³ . The density of ammonia liquid under normal conditions is 686 kg / m ³ . The molecular weight of the substance is 17.2 g / mol. A distinctive feature of ammonia is its high solubility in water. So, at a temperature of 0 ° C, its value reaches about 1200 volumes in the water volume, at 20 ° C - 700 volumes. The solution "ammonia-water" (ammonia water) is characterized by a slightly alkaline reaction and a rather unique property in comparison with other alkalis: with increasing concentration, the density decreases.

How is ammonia formed?

What is ammonia in the human body? This is the final product of nitrogen metabolism. Most of the liver converts to urea (carbamide) - a less toxic substance.

Ammonia in natural conditions is formed as a result of the decomposition of organic compounds containing nitrogen. For use in industry this substance is produced by artificial means.

Production of ammonia in industrial and laboratory conditions

In industrial conditions, ammonia is produced by catalytic synthesis from nitrogen and hydrogen:

N ₂ + 3H ₂ → 2NH 3 + Q.

The process of obtaining the substance is carried out at a temperature of 500 ° C and a pressure of 350 atm. Porous iron is used as the catalyst. The resulting ammonia is removed by cooling. Nitrogen and hydrogen, which have not reacted, return to synthesis.

Under laboratory conditions, ammonia is produced mainly by mildly heating a mixture consisting of ammonium chloride and hydrated lime:

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

For drying, the finished compound is passed through a mixture of lime and sodium hydroxide. Quite dry ammonia can be obtained by dissolving metallic sodium in it and subsequent distillation.

Where is ammonia used?

Hydrogen nitride is widely used in various industries. Huge amounts of it are used for the production of nitric acid and various fertilizers (urea, ammonium nitrate, etc.), polymers, hydrocyanic acid, soda, ammonium salts and other chemical products.

In the light industry, the properties of ammonia are used in the cleaning and staining of such fabrics as silk, wool and cotton. In steelmaking, it is used to increase the hardness of steel by saturating its surface layers with nitrogen. Acid waste is neutralized in the petrochemical industry with the help of hydrogen nitride.

Due to its thermodynamic properties, liquid ammonia is used as a coolant in refrigeration equipment.

A solution of hydrogen nitride (ammonia) is used in medicine for removal from syncope, stimulation of vomiting, treatment of the hands of medical staff, with insect bites, etc.

Some chemical properties of ammonia

Hydrogen nitride is characterized by a rather high chemical activity and is able to react with many substances.

When ammonia reacts with acids, the corresponding ammonium salts are formed. For example, as a result of the reaction with nitric acid, ammonium nitrate is formed :

NH ₃ + HNO ₃ → NH ₄ NO _3.

In the reaction with HCl, ammonium chloride is formed:

NH ₃ + HCl → NH ₄ Cl.

Ammonium salts are solid crystalline substances that decompose in water and possess the properties inherent in metal salts. Solutions of compounds formed as a result of the interaction of ammonia and strong acids have a weakly acid reaction.

Due to nitrogen atoms, hydrogen nitride is an active reducing agent. Its reducing properties are manifested when heated. When burning in an oxygen atmosphere, it forms nitrogen and water. In the presence of catalysts, the interaction with oxygen gives nitric oxide. Hydrogen nitride has the ability to reduce metals from oxides.

Halogens react with ammonia to form halogenides of nitrogen - dangerous explosives. When interacting with carboxylic acids and their derivatives, hydrogen nitride forms amides. In reactions with coal (at 1000 ° C) and methane, it gives cyanide.

With metal ions, ammonia forms amine complexes, or ammonia (complex compounds), which have a characteristic feature: a nitrogen atom is always bound to three hydrogen atoms. As a result of complexation, the color of the substance changes. So, for example, a blue solution of copper sulfate with the addition of hydrogen nitride acquires an intense blue-violet color. Many of the aminocomplexes possess sufficient stability. Due to this, they can be obtained in solid form.

In liquid ammonia, both ionic and nonpolar inorganic and organic compounds are readily soluble.

Sanitary and hygienic characteristics

Ammonia is classified as the fourth hazard class. The maximum permissible maximum-one-time concentration (MPC) in the air of settlements is 0.2 mg / m ³ , the average daily - 0.04. In the air of the working area, the ammonia content should not be above 20 mg / m³. At such concentrations, the smell of the substance is not felt. It is recorded by human smell, it starts at 37 mg / m³. That is, if the smell of ammonia is felt, this means that the permissible standards for the presence of matter in the air are significantly exceeded.

Influence on the human body

What is ammonia in terms of human exposure? It's a toxicant. It is classified as a substance capable of exerting a suffocating and neurotropic effect, inhalation poisoning which can lead to pulmonary edema and damage to the nervous system.

Ammonia vapor irritates the skin, mucous membranes of the eyes and respiratory organs. The concentration of the substance at which irritation of the throat is manifested is 280 mg per cubic meter. Meter, eye - 490 mg per cubic meter. meter. Depending on the amount of hydrogen nitride in the air, there may be a swelling in the throat, difficulty breathing, coughing attacks, eye pain, profuse lacrimation, chemical burn of the cornea, loss of vision. With an ammonia content of 1.5 g per cubic meter. Meter for an hour develops toxic pulmonary edema. When liquid ammonia and its solutions (in high concentrations) come into contact with the skin, redness, itching, burning, dermatitis are possible. Since liquefied nitride of the water conduit absorbs heat during evaporation, frostbite of various degrees is possible.

Symptoms of poisoning with ammonia

Poisoning with this toxicant can cause a decrease in the auditory threshold, nausea, dizziness, headache, etc. There may be changes in behavior, in particular, intense excitement, delirium. The manifestation of symptoms in a number of cases is intermittent. They can stop for a while, and then resume with renewed vigor.

Taking into account all possible consequences of ammonia exposure, it is very important to observe precautions when working with this substance and not to exceed its concentration in the air.