Ammonia - union, is an important source of nitrogen for living organisms, and have found application in various industries.What is ammonia, what are its properties?Let's face it.
What ammonia basic characteristics
Ammonia (nitride conduit) - a compound of nitrogen and hydrogen, has the chemical formula NH3.The shape of the molecule resembles a trigonal pyramid, in the top of which is a nitrogen atom.
Ammonia is a gas that has no color, but has a sharp specific smell.Ammonia density is almost two times less than the density of air.At the temperature 15 oC it is 0.73 kg / m3.The density of liquid ammonia under normal conditions is 686 kg / m3.The molecular weight of the substance - 17.2 g / mol.A distinctive feature of ammonia is its high solubility in water.Thus, at a temperature of 0 ° C it reaches a value of about 1200 volumes in a volume of water at 20 ° C - 700 volumes.A solution of "ammonia - water" (ammonia water) has a slightly alkaline reaction and fairly unique property compared to other alkalis: concentration increases the density decreases.
How to produce ammonia?
What ammonia in the human body?It is the end product of nitrogen metabolism.Most of it in the liver converts urea (carbamide) - less toxic.
Ammonia natural environment formed by the decomposition of organic compounds containing nitrogen.For use in the industry is a substance obtained synthetically.
ammonia in industrial and laboratory
Industrially ammonia produced by catalytic synthesis from nitrogen and hydrogen:
N2 + 3H2 → 2NH3 + Q.
process of obtaining the substance is carried out at a temperature of 500 ° C and a pressure of 350 atm.As used porous iron catalyst.The resulting ammonia is removed by cooling.Nitrogen and hydrogen unreacted returned to the synthesis.
Under laboratory conditions the ammonia produced in the main by a weak heating a mixture of ammonium chloride and lime:
2NH4Cl + Ca (OH) 2 → CaCl2 + 2NH3 ↑ + 2H2O.
ready for drying compound is passed through a mixture of lime and caustic soda.Enough dry ammonia can be prepared by dissolving sodium metal therein and subsequent distillation.
Where ammonia is used?
nitride hydrogen is widely used in various industries.Huge amounts of it are used for the production of nitric acid and various fertilizers (urea, ammonium nitrate, and others.), Polymers of hydrocyanic acid, soda ash, ammonium salts and other chemical products.
in light industrial properties of ammonia is used in cleaning and dyeing of fabrics such as silk, wool and cotton.In the steel industry, it is used to increase the hardness of the steel surface by saturating it with nitrogen layers.In the petrochemical industry using hydrogen nitride neutralized acidic wastes.
Due to its thermodynamic properties of liquid ammonia used as a refrigerant in refrigeration equipment.
solution nitride hydrogen (ammonia) used in medicine for the withdrawal of syncope, the stimulation of vomiting, for the treatment of the hands of medical personnel, insect bites and so on.
Some chemical properties of ammonia
nitride hydrogen is characterized by a relatively high reactivity andcapable of reacting with many substances.
In the reaction of ammonia with an acid to give the corresponding ammonium salts.Thus, for example, by reaction with nitric acid, ammonium nitrate is formed:
NH3 + HNO3 → NH4NO3.
The interaction of the HCl formed ammonium chloride:
NH3 + HCl → NH4Cl.
ammonium salts are crystalline solids that decompose in the water and have the inherent characteristics of metal salts.Solutions of the compounds formed by reaction of ammonia and the strong acid are slightly reaction.
Due to the nitrogen atoms of hydrogen nitride is the active reducing agent.Reducing properties of its manifest when heated.When burned in an oxygen atmosphere, it forms a nitrogen and water.In the presence of a catalyst for the reaction with oxygen provides an oxide of nitrogen.Nitride hydrogen has the ability to recover metals from oxides.
Halides by reaction with ammonia to form nitrogen halides - dangerous explosives.The interaction of carboxylic acids and their derivatives nitride hydrogen form amides.In reactions with coal (at 1000 ° C) and methane it gives prussic acid.
with metal ions, ammonia forms amino complexes or ammines (complexes) with a characteristic feature: a nitrogen atom is always bonded to three hydrogen atoms.As a result of complex changes coloring substances.So, for example, the blue copper sulfate solution by adding hydrogen nitride acquires an intense blue-violet color.Many of the amino complexes are sufficiently stable.Because of this they can be prepared in solid form.
in liquid ammonia dissolve well as ionic and nonpolar inorganic and organic compounds.
Sanitation characteristics
Ammonia belongs to the fourth class of danger.Maximum allowable maximum one-time concentration (MAC) in the air of the settlements is 0.2 mg / m3, average - 0.04.In the air of the working area of ammonia should not be higher than 20 mg / m³.At such concentrations, the smell of a substance is not felt.Recorded human sense of smell, he starts at 37 mg / m³.That is, if ammonia odor felt, which means that the permissible limits of finding substances in the air greatly exceeded.
Influence on the human body
What ammonia in terms of human exposure?It toxicant.It refers to a substance capable of exerting suffocating and neurotropic action, inhalation poisoning which can lead to swelling of the lungs and nervous system.
Ammonia vapors irritating effect on the skin, mucous membranes, eyes and respiratory system.The concentration of the substance in which manifested throat irritation, 280 mg per cubic meters.meter eye - 490 mg per cubic meters.meter.Depending on the amount of hydrogen nitride in the air can occur sore throat, difficulty breathing, coughing, pain in the eyes, excessive tearing, a chemical burn of the cornea, loss of vision.If the ammonia content of 1.5 grams per cubic meters.meter per hour toxic pulmonary edema develops.When contacting the liquid ammonia and the solutions (in high concentrations) may skin redness, itching, burning and dermatitis.Since liquefied nitride conduit absorbs heat by evaporation, frostbite varying degrees.
Symptoms of ammonia poisoning
Poisoning According toxicant could cause a reduction in the threshold of hearing, nausea, dizziness, headache and so on. There may be changes in behavior, in particular the great excitement, delirium.Onset of symptoms in some cases is intermittent.They can stop for a while and then resumed with renewed vigor.
Considering all the possible effects of ammonia, it is important to take precautions when working with this substance, and not to exceed its concentration in the air.
