Ammonia (NH3) is a chemical compound of hydrogen and nitrogen.It got its name from the Greek word «hals ammniakos» latin «sal ammoniacus» which translates Odinokova - "ammonia."It is a substance called ammonium chloride obtained in the Libyan desert in an oasis of Ammonium.
Ammonia is considered a very toxic substance that is able to irritate the mucous membranes of the eyes and respiratory tract.The primary symptoms of ammonia poisoning are profuse watery eyes, shortness of breath and pneumonia.At the same time, ammonia - a valuable chemical which is widely used for the preparation of inorganic acids such as nitric acid, hydrocyanic and urea and nitrogen salts.Liquid ammonia - is an excellent working fluid containers and refrigerated trucks, since it has a large specific heat of vaporization.Aqueous ammonia is used as a liquid fertilizer and for the ammoniation superphosphate fertilizer, and mixtures thereof.
ammonia from waste gases in coking coal is the oldest and highly accessible method, but today it is already outdated and little used.
Modern and the main way is to obtain ammonia in the industry based on the Haber process.Its essence direct reaction of hydrogen and nitrogen, which occurs in the conversion of hydrocarbon gases.The feedstock typically appear natural gas, refinery gas, associated gas, residual gases from the production of acetylene.The method includes the conversion ammonia in the decomposition of methane and its homologs with high temperature components of the hydrogen and carbon monoxide with oxidants - oxygen and water vapor.When this gas is admixed to the convertible oxygen enriched air or air.Initially, the reaction of ammonia on the basis of the convertible gas flows from the heat, but with a decrease in the volume of initial reaction products:
N2 + 3H2 ↔ 2NH3 + 45,9 kJ
However, the production of ammonia on an industrial scale is carried out using a catalyst and artificiallyto create the conditions that allow to increase the yield of the final product.In the atmosphere, where the ammonia increases the pressure to 350 atmospheres, and the temperature rises to 500 degrees Celsius.Under these conditions, the yield of ammonia - about 30%.Gas removed from the reaction zone via the cooling method, and nitrogen and hydrogen, which have not reacted are returned to the synthesis column and may again participate in the reactions.In the course of the synthesis it is very important to clean the gas mixture from the catalyst poisons, substances that can negate the effect of catalysts.Such materials are water vapor, CO, As, P, Se, O2, S.
as catalyst in the synthesis reaction of nitrogen and hydrogen acts porous iron alloy oxides of aluminum and potassium.Only a substance of 20 000 all previously tried, allowing the reaction to reach equilibrium.This principle of ammonia is considered to be the most economical.
ammonia in the laboratory based on the technology of repression of its ammonium salts of strong alkalis.Schematically, the reaction is as follows:
2NH4CI + Ca (OH) 2 = 2NH3 ↑ + CaCl2 + 2H2O
or
NH4Cl + NaOH = NH3 ↑ + NaCl + H2O
to remove excess moisture and dry the ammonia, it is passedthrough a mixture of caustic soda and lime.Preparation of very dry ammonia is achieved by dissolving sodium metal therein and subsequent distillation of the mixture.In most cases such reactions are carried out in a closed system under vacuum metal.Moreover, such a system must withstand the high pressure which is achieved stand out with ammonia vapors to 10 atmospheres at room temperature.
