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{{chembox new| ImageFileL1 = Ammonia-2D-dimensions.png| ImageSizeL1 = 150 px| ImageFileR1 = Ammonia-3D-vdW.png| ImageSizeR1 = 150 px| IUPACName = Azane| OtherNames = AmmoniaHydrogen nitrideSpirit of hartshorn
Nitrosil
Vaporole Ammonia data at NIST Webbook, last accessed May 7 2007.| Section1 = {{Chembox Identifiers| CASNo = 7664-41-7| PubChem = 222| SMILES = N| InChI = 1/H3N/h1H3| RTECS = BO0875000-->| Section2 = {{Chembox Properties| Formula = NH3| MolarMass = 17.0306 g/mol| Appearance = Colorless gas with strong pungent odor| Density = 0.6942 NIST Chemistry WebBook (website page of the National Institute of Standards and Technology) URL last accessed May 15 2007| MeltingPt = -77.73 °C (195.42 Kelvin)| Melting_notes =| BoilingPt = -33.34 °C (239.81 K)| Boiling_notes =| Solubility = 89.9 g/100 Milliliter at 0 °Celsius| SolubleOther =| Solvent =| pKa = 36 (ionization to NH2-)| pKa = 9.25 (formation of NH4+)| RefractIndex = Dielectric constant-->| Section3 = {{Chembox Structure| MolShape = Terminus| Dipole = 1.42 Debye-->| Section7 = {{Chembox Hazards| MainHazards = Hazardous gas, caustic, corrosive| NFPA-H = 3| NFPA-F = 1| NFPA-R =| NFPA-O =| RPhrases = , , , , , ,
, | SPhrases =| RSPhrases =| FlashPt = None MSDS Sheet from W.D. Service Co.| Autoignition = 651 °C| ExploLimits =| PEL = -->| Section8 = {{Chembox Related| OtherAnions = ammonium hydroxide (NH4OH)| OtherCations = Ammonium (NH4+)] (NH4Cl)| Function =| OtherCpds = Hydrazine
Hydrazoic acid
Hydroxylamine
Chloramine -->-->Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor. Ammonia contributes significantly to the nutritional needs of the planet as a precursor to foodstuffs and fertilizers. Ammonia, either directly or indirectly, is a building block for the synthesis of most pharmaceuticals. Although it is in wide use, ammonia is caustic and hazardous.

Ammonia used commercially is usually named anhydrous ammonia. This term emphasizes the absence of water. Because NH3 boils at -33 °C, the liquid must be stored under pressure or at low temperature. Its heat of vaporization is, however, sufficiently high that NH3 can be readily handled in ordinary beakers in a fume hood. "Household ammonia" or "ammonium hydroxide" is a solution of NH3 in water. The strength of such solutions is measured in units of baume (density), with 26 degrees baume (about 30 weight percent ammonia at 15.5 °C) being the typical high concentration commercial product. Ammonium hydroxide physical properties Household ammonia ranges in concentration from 5 to 10 weight percent ammonia. See Baumé scale.

Structure and basic chemical properties The ammonia molecule has a Trigonal pyramid (chemistry) shape, as predicted by VSEPR theory. The nitrogen atom in the molecule has a Lone pair, and ammonia acts as a Base (chemistry), a proton acceptor. This shape gives the molecule an overall dipole moment and makes it Polar molecule so that ammonia readily dissolves in Water (molecule). In water, a very small percentage of NH3 is converted into the ammonium cation (NH4+). Thus, the term ammonium hydroxide is a misnomer. The degree to which ammonia forms the ammonium ion increases upon lowering the pH of the solution— at "physiological" pH (~7), about 99% of the ammonia molecules are Protonation. Temperature and salinity also affect the proportion of NH4+. NH4+ has the shape of a regular tetrahedron.

The main uses of ammonia are in the production of fertilizers, explosives, and organic synthesis of organonitrogen compounds. It is also the active ingredient in household glass cleaners. Ammonia is found in small quantities in the atmosphere, being produced from the putrefaction of nitrogenous animal and vegetable matter. Ammonia and ammonium salts are also found in small quantities in rainwater, whereas ammonium chloride (sal-ammoniac), and ammonium sulfate are found in volcanic districts; crystals of ammonium bicarbonate have been found in Patagonian guano. The kidneys secrete NH3 to neutralize excess acid. electrolytes and the urine anion and osmolar gaps. Ammonium salts also are found distributed through all fertile soil and in seawater. Substances containing ammonia, or those that are similar to it, are called ammoniacal.

History Salts of ammonia have been known from very early times; thus the term Hammoniacus sal Webmineral website URL last accessed August 27 2006 appears in the writings of Pliny the Elder, although it is not known whether the term is identical with the more modern sal-ammoniac.

In the form of sal-ammoniac, ammonia was known to the alchemy as early as the 13th century, being mentioned by Albertus Magnus. Absolouteastronomy.com URL last accessed April 24 2006 It was also used by dyers in the Middle Ages in the form of fermented urine to alter the colour of vegetable dyes. In the 15th century, Basilius Valentinus showed that ammonia could be obtained by the action of alkalis on sal-ammoniac. At a later period, when sal-ammoniac was obtained by distilling the hoofs and horns of oxen and neutralizing the resulting carbonate with hydrochloric acid, the name "spirit of hartshorn" was applied to ammonia.

Gaseous ammonia was first isolated by Joseph Priestley in 1774 and was termed by him alkaline air; however it was acquired by the alchemist Basil Valentine. Abraham, Lyndy. Marvell and alchemy. Aldershot Scolar 1990. Eleven years later in 1785, Claude Louis Berthollet ascertained its composition.

The Haber process to produce ammonia from the nitrogen in the air was developed by Fritz Haber and Carl Bosch in 1909 and patented in 1910. It was first used on an industrial scale by the Germans during World War I, BBC.co.uk URL last accessed April 24 2006 following the allied blockade that cut off the supply of nitrates from Chile. The ammonia was used to produce explosives to sustain their war effort.Smith, Roland. Conquering Chemistry 2001

Synthesis and production Because of its many uses, ammonia is one of the most highly-produced inorganic chemicals. Dozens of chemical plants worldwide produce ammonia. The worldwide ammonia production in 2004 was 109 million metric tonnes. United States Geological Survey publication The People's Republic of China produced 28.4% of the worldwide production followed by India with 8.6%, Russia with 8.4%, and the United States with 8.2%. About 80% or more of the ammonia produced is used for fertilizing agricultural crops.

Before the start of World War I, most ammonia was obtained by the dry distillation Nobel Prize in Chemistry (1918) - Haber process. URL last accessed April 24 2006 of nitrogenous vegetable and animal waste products, including camel manure, where it was distillation by the reduction of nitrous acid and nitrites with hydrogen; in addition, it was produced by the distillation of coal, and also by the decomposition of ammonium salts by alkaline hydroxides BBC.co.uk URL last accessed April 24 2006 such as calcium oxide, the salt most generally used being the chloride (ammonium chloride) thus:

:2 NH4Cl + 2 CaO → CaCl2 + Ca(OH)2 + 2 NH3

Today, the typical modern ammonia-producing plant first converts natural gas (i.e., methane) or liquified petroleum gas (such gases are propane and butane) or petroleum naphtha into gaseous hydrogen. Starting with a natural gas feedstock, the processes used in producing the hydrogen are:

:H2 + RSH → RH + H2S(g)

:H2S + ZnO → ZnS + H2O

:CH4 + H2O → CO + 3 H2

:CO + H2O → CO2 + H2



:CO + 3 H2 → CH4 + H2O :CO2 + 4 H2 → CH4 + 2 H2O



:3 H2 + N2 → 2 NH3

The steam reforming, shift conversion, carbon dioxide removal and methanation steps each operate at absolute pressures of about 25 to 35 Bar (unit), and the ammonia synthesis loop operates at absolute pressures ranging from 60 to 180 bar, depending upon which proprietary design is used. There are many engineering and construction companies that offer proprietary designs for ammonia synthesis plants. Haldor Topsoe of Denmark, Lurgi AG of Germany, ThyssenKrupp of Germany, and Kellogg, Brown and Root of the United States are among the most experienced companies in that field. Kellogg Brown's Ammonia Process URL last accessed April 24 2006

As the availability and usage of fossil fuel become problematic (see peak oil and climate change), the hydrogen needed for ammonia synthesis can be obtained from electrolysis or thermal chemical cracking of water. In such case, the heat needed for thermal cracking can be obtained from nuclear reaction, while the electricity needed for electrolysis can be obtained from various renewable energy sources such as Wind turbine, Photovoltaics, hydroelectricity, and various forms of ocean energy especially that of OTEC.

Biosynthesis In certain organisms, ammonia is produced from atmospheric N2 by enzymes called nitrogenases. The overall process is called nitrogen fixation. Although it is unlikely that biomimetic methods will be developed that are competitive with the Haber process, intense effort has been directed toward understanding the mechanism of biological nitrogen fixation. The scientific interest in this problem is motivated by the unusual structure of the active site of the enzyme, which consists of an Fe7MoS9 ensemble.

Ammonia is also a metabolic product of amino acid deamination. In humans, it is quickly converted to urea, which is much less toxic. This urea is a major component of the dry weight of urine.

Properties Ammonia is a colorless gas with a characteristic pungent smell similar to human urine, as the urine contains an amount of ammonia in it. It is lighter than air, its density being 0.589 times that of Earth's atmosphere. It is easily liquefied due to the strong hydrogen bonding between molecules; the liquid boils at -33.3 °C, and solidifies at -77.7 °C to a mass of white crystals. Liquid ammonia possesses strong ionizing powers (Dielectric constant = 22), and solutions of salts in liquid ammonia have been much studied. Liquid ammonia has a very high standard enthalpy change of vaporization (23.35 Joule/mol, cf. water (molecule) 40.65 kJ/mol, methane 8.19 kJ/mol, phosphine 14.6 kJ/mol) and can therefore be used in laboratories in non-insulated vessels at room temperature, even though it is well above its boiling point.

It is miscible with water. All the ammonia contained in an aqueous solution of the gas may be expelled by boiling. The water solution of ammonia is Base (chemistry). The maximum concentration of ammonia in water (a saturation (chemistry) solution) has a density of 0.880 g /cubic centimetre and is often known as '.880 Ammonia'. Ammonia does not burn readily or sustain combustion, except under narrow fuel to air mixtures from 15-25% air. When mixed with oxygen, it burns with a pale yellowish-green flame. At high temperature and in the presence of a suitable catalyst, ammonia is decomposed into its constituent elements. Chlorine catches fire when passed into ammonia, forming nitrogen and hydrochloric acid; unless the ammonia is present in excess, the highly explosive nitrogen trichloride (NCl3) is also formed.

The ammonia molecule readily undergoes nitrogen inversion at room temperature - that is, the nitrogen atom passes through the plane of symmetry of the three hydrogen atoms; a useful analogy is an umbrella turning itself inside out in a strong wind. The energy barrier to this inversion is 24.7 kJ/mol in ammonia, and the resonance frequency is 23.79 Hertz, corresponding to microwave radiation of a wavelength of 1.260 cm. The absorption at this frequency was the first Microwave spectroscopy to be observed.C. E. Cleeton & N. H. Williams, 1934 - Online version; archive. URL last accessed May 8, 2006

Formation of salts One of the most characteristic properties of ammonia is its power of combining directly with acids to form salts; thus with hydrochloric acid it forms ammonium chloride (sal-ammoniac); with nitric acid, ammonium nitrate, etc. However perfectly dry ammonia will not combine with perfectly dry hydrogen chloride, a gas, moisture being necessary to bring about the reaction.Baker, H. B. (1894). J. Chem. Soc. 65: 612. :NH3 + Hydrochloric acid → Ammonium chloride

The salts produced by the action of ammonia on acids are known as the :Category:Ammonium compounds and all contain the ammonium ion (NH4+).

Acidity Although ammonia is well-known as a base, it can also act as an extremely weak acid. It is a protic substance, and is capable of dissociation into the amide (NH2−) ion, for example when solid lithium nitride is added to liquid ammonia, forming a lithium amide solution:

:Li3N(s)+ 2 NH3 (l) → 3 Li+(am) + 3 NH2−(am)

This is a Brønsted-Lowry acid-base reaction in which ammonia is acting as an acid.

Formation of other compounds Ammonia can act as a nucleophile in Nucleophilic substitution reactions. Amines can be formed by the reaction of ammonia with alkyl halides, although the resulting –NH2 group is also nucleophilic and secondary and tertiary amines are often formed as by-products. Using an excess of ammonia helps minimise multiple substitution, and neutralises the hydrogen halide formed. Methylamine is prepared commercially by the reaction of ammonia with chloromethane, and the reaction of ammonia with 2-bromopropanoic acid has been used to prepare racemic alanine in 70% yield. Ethanolamine is prepared by a ring-opening reaction with ethylene oxide: the reaction is sometimes allowed to go further to produce diethanolamine and triethanolamine.

Amides can be prepared by the reaction of ammonia with a number of carboxylic acid derivatives. Acyl chlorides are the most reactive, but the ammonia must be present in at least a twofold excess to neutralise the hydrogen chloride formed. Esters and anhydrides also react with ammonia to form amides. Ammonium salts of carboxylic acids can be Dehydration to amides so long as there are no thermally sensitive groups present: temperatures of 150–200 °C are required.

The hydrogen in ammonia is capable of replacement by metals, thus magnesium burns in the gas with the formation of magnesium nitride Mg3N2, and when the gas is passed over heated sodium or potassium, sodamide, NaNH2, and potassamide, KNH2, are formed. Where necessary in IUPAC nomenclature, IUPAC recommendations prefer the name azane to ammonia: hence chloramine would be named chloroazane in substitutive nomenclature, not chloroammonia.

Ammonia as a ligand of the tetraamminecopper(II) cation, 2+

]

Ammonia can act as a ] in transition metal complex (chemistry). It is a pure σ-donor, in the middle of the spectrochemical series, and shows intermediate HSAB concept behaviour. For historical reasons, ammonia is named ammine in the nomenclature of coordination compounds. Some notable ammine complexes include:

Ammine complexes of chromium(III) were known in the late 19th century, and formed the basis of Alfred Werner's theory of coordination compounds. Werner noted that only two isomers (fac- and mer-) of the complex could be formed, and concluded that the ligands must be arranged around the metal ion at the wikt:vertex of an octahedron. This has since been confirmed by X-ray crystallography.

An ammine ligand bound to a metal ion is markedly more acidic than a free ammonia molecule, although deprotonation in aqueous solution is still rare. One example is the Mercury(I) chloride, where the resulting amidomercury(II) compound is highly insoluble. :Hg2Cl2 + 2 NH3 → Hg + HgCl(NH2) + NH4+ + Cl−

Uses Nitric Acid production The most important single use of ammonia is in the production of nitric acid. A mixture of one part ammonia to nine parts air is passed over a platinum gauze catalyst at 850 °C, whereupon the ammonia is oxidisation to nitric oxide.

:4 NH3 + 5 O2 → 4 NO + 6 H2O :2 NO + O2 → 2 NO2 :2 NO2 + 2 H2O → 2 HNO3 + H2

The catalyst is essential, as the normal oxidation (or combustion) of ammonia gives Nitrogen and water: the production of nitric oxide is an example of kinetic control. As the gas mixture cools to 200–250 °C, the nitric oxide is in turn oxidized by the excess of oxygen present in the mixture, to give nitrogen dioxide. This is reacted with water to give nitric acid for use in the production of fertilizers and explosives.

Universal Indicator Ammonia solution is also used as universal indicator that could be used to test for different gases that require a universal indicator solution to show the gases were present.

Fertilizer In addition to serving as a fertilizer ingredient, ammonia can also be used directly as a fertilizer by forming a solution with irrigation water, without additional chemical processing. This later use allows the continuous growing of nitrogen dependent crops such as maize (corn) without agriculture rotation but this type of use leads to poor soil health.

Refrigeration Ammonia's thermodynamic properties made it one of the refrigerants commonly used in refrigeration units prior to the discovery of dichlorodifluoromethane Dichlorodifluoromethane by Aaron Vorderstrasse, Western Oregon University. in 1928, also known as Freon or R12.

But ammonia is toxic, gaseous, irritant, and corrosive to copper alloys, and over a kilo is needed for even a miniature fridge. With an ammonia refrigerant, the ever present risk of an escape brings with it a risk to life. However data on ammonia escapes has shown this to be an extremely small risk in practice, and there is consequently no control on the use of ammonia refrigeration in densely populated areas and buildings in almost all jurisdictions in the world.

Its use in domestic refrigeration has been mostly replaced by CFCs and HFCs in the first world, which are more or less non-toxic and non-flammable, and butane and propane in the 3rd world, which despite their high flammable do not seem to have produced any significant level of accidents. Ammonia has continued to be used for miniature and multifuel fridges, such as minibars and caravan fridges.

These ammonia absorption cycle domestic refrigerators do not use compression and expansion cycles, but are driven by temperature differences. However the energy efficiency of such refrigerators is relatively low. Today the smallest refrigerators mostly use solid state peltier thermopile heat pumps rather than the ammonia absorption cycle.

Ammonia continues to be used as a refrigerant in large industrial processes such as bulk icemaking and industrial food processing. Since the implication of haloalkanes being major contributors to ozone depletion, ammonia is again seeing increasing use as a refrigerant.

Disinfectant It is also sometimes added to drinking water along with chlorine to form chloramine, a disinfectant. Unlike chlorine on its own, chloramine does not combine with organic (carbon containing) materials to form carcinogenic halomethanes such as chloroform. However, chlorine and ammonia should never be mixed in an uncontrolled environment because they cause a chemical reaction that releases toxic gas. See Ammonia#Safety precautions for more information.

Fuel Liquid ammonia was used as the fuel of the rocket airplane, the X-15. Although not as powerful as other fuels, it left no soot in the reusable rocket engine, and has about the same density as the oxidizer, liquid oxygen, which simplified the aircraft's keeping the same center of gravity in flight. Anhydrous ammonia is a practical clean (Carbon dioxide-free) and renewable fuel which can be and has been used to replace fossil fuel in powering internal combustion engines.http://www.energy.iastate.edu/becon/ammonia.html In 1981 a Canadian company converted a 1981 Chevrolet Impala to run on an ammonia fuel.http://www.youtube.com/watch?v=L0hBAz6MxC4http://www.gregvezina.com

Cigarettes During the 1960s, tobacco companies such asBrown & Williamson and Philip Morris began using ammonia in cigarettes. The addition of ammonia serves to enhance the delivery of nicotine into the blood stream. As a result, the reinforcement effect of the nicotine was enhanced, increasing its addictive ability without actually increasing the portion of nicotine.Alix M. Freedman, " 'Impact Booster': Tobacco Firm Shows How Ammonia Spurs Delivery of Nicotine", The Wall Street Journal, Dec. 28, 1995.

Ammonia's role in biologic systems and human disease Ammonia is an important source of nitrogen for living systems. Although atmospheric nitrogen abounds, few living creatures are capable of utilizing this nitrogen. Nitrogen is required for the synthesis of amino acids, which are the building blocks of protein. Some plants rely on ammonia and other nitrogenous wastes incorporated into the soil by decaying matter. Others, such as nitrogen-fixing legumes, benefit from symbiosis relationships with rhizobia which create ammonia from atmospheric nitrogen.M.B. Adjei, K.H. Quesenberry and C.G. Chamblis. Nitrogen Fixation and Inoculation of Forage Legumes University of Florida IFAS Extension June 2002.

Ammonia also plays a role in both normal and abnormal animal physiology. Ammonia is created through normal amino acid metabolism and is toxic in high concentrations. PubChem Substance Summary, last accessed May 7 2007 The liver converts ammonia to urea through a series of reactions known as the urea cycle. Liver dysfunction, such as that seen in cirrhosis, may lead to elevated amounts of ammonia in the blood (hyperammonemia). Likewise, defects in the enzymes responsible for the urea cycle, such as ornithine transcarbamylase, lead to hyperammonemia. Hyperammonemia contributes to the confusion and coma of hepatic encephalopathy as well as the neurologic disease common in people with urea cycle defects and organic acidurias.Zschocke, Johannes, and Georg Hoffman. Vademecum Metabolism. Friedrichsdorf, Germany: Milupa GmbH, 2004.

Ammonia is important for normal animal acid/base balance. After formation of ammonium from glutamine, α-ketoglutarate may be degraded to produce two molecules of bicarbonate which are then available as buffers for dietary acids. Ammonium is excreted in the urine resulting in net acid loss. Ammonia may itself diffuse across the renal tubules, combine with a hydrogen ion, and thus allow for further acid excretion.Rose, Burton, and Helmut Rennke. Renal Pathophysiology. Baltimore, Maryland: Williams & Wilkins, 1994.

Theoretical role in alternative biochemistry Ammonia has been proposed as a possible replacement for water as a bodily solvent in the theoretical alternative biochemistries of lifeforms that do not use carbon for cellular structure and water as a solvent to dissolve bodily solutes and allow essential parts of metabolic processes to occur. It is suggested that ammonia would be most favorable for lifeforms that live in temperatures lower than the freezing point of water.Lazio, Joseph, Why do we assume that other beings must be based on carbon? Why couldn't organisms be based on other substances? sci.astro, ET Life (Astronomy Frequently Asked Questions). Retrieved on 2007-04-27.

Liquid ammonia as a solvent See also: Inorganic nonaqueous solvent Liquid ammonia is the best-known and most widely studied non-aqueous ionizing solvent. Its most conspicuous property is its ability to dissolve alkali metals to form highly coloured, electrically conducting solutions containing solvated electrons. Apart from these remarkable solutions, much of the chemistry in liquid ammonia can be classified by analogy with related reactions in aqueous solutions. Comparison of the physical properties of NH3 with those of water shows that NH3 has the lower melting point, boiling point, density, viscosity, dielectric constant and electrical conductivity; this is due at least in part to the weaker H bonding in NH3 and the fact that such bonding cannot form cross-linked networks since each NH3 molecule has only 1 lone-pair of electrons compared with 2 for each H2O molecule. The ionic self-dissociation constant of liquid NH3 at −50 °C is approx. 10-33 mol2·l-2.

Solubility of salts {||-!  ! Solubility (g of salt per 100 g liquid NH3)|-| Ammonium acetate| 389.6|-| [Lithium nitrate| 97.6|-| [Potassium nitrate| 0.35|-| [Sodium chloride| 138.0|-| [Sodium iodide| 205.5|-|}

Liquid ammonia is an ionizing solvent, although less so than water, and dissolves a range of ionic compounds including many [nitrates, nitrites, cyanides and thiocyanates. Most ammonium salts are soluble, and these salts act as acids in liquid ammonia solutions. The solubility of halide salts increases from fluoride to iodide. A saturated solution of ammonium nitrate contains 0.83 mol solute per mole of ammonia, and has a vapour pressure of less than 1 bar even at 25 °C.

Solutions of metals See also: Solvated electron, metallic solution Liquid ammonia will dissolve the alkali metals and other Electronegativity metals such as calcium, strontium, barium, europium and ytterbium. At low concentrations (Anhydrous ammonia is classified as toxic (T) and dangerous for the environment (N). The gas is flammable (autoignition temperature: 651 °C) and can form explosive mixtures with air (16–25%). The permissible exposure limit (PEL) in the United States is 50 Parts per million (35 mg/m3), while the IDLH concentration is estimated at 300 ppm. Repeated exposure to ammonia lowers the sensitivity to the smell of the gas: normally the odour is detectable at concentrations of less than 0.5 ppm, but desensitized individuals may not detect it even at concentrations of 100 ppm. Anhydrous ammonia corrodes copper (element)- and zinc (element)-containing alloys, and so brass fittings should not be used for handling the gas. Liquid ammonia can also attack rubber and certain plastics.

Ammonia reacts violently with the halogens, and causes the explosive polymerization of ethylene oxide. It also forms explosive compounds with compounds of gold (element), silver, Mercury (element), germanium or tellurium, and with stibine. Violent reactions have also been reported with acetaldehyde, hypochlorite solutions, potassium ferricyanide and peroxides.

Safety The U. S. Occupational Safety and Health Administration has set a 15-minute exposure limit for gaseous ammonia of 35 ppm by volume in the environmental air and an 8-hour exposure limit of 25 ppm by volume. Toxic FAQ Sheet for Ammonia published by the Agency for Toxic Substances and Disease Registry (ATSDR), September 2004 Exposure to very high concentrations of gaseous ammonia can result in lung damage and death. Although ammonia is regulated in the United States as a non-flammable gas, it still meets the definition of a material that is toxic by inhalation and requires a hazardous safety permit when transported in quantities greater than 13,248 L (3,500 gallons). Hazardous Materials (HM) Safety Permits from the website of the United States Department of Transportation (DOT)

See also

References

Bibliography

External links



{{chembox new| ImageFileL1 = Ammonia-2D-dimensions.png| ImageSizeL1 = 150 px| ImageFileR1 = Ammonia-3D-vdW.png| ImageSizeR1 = 150 px| IUPACName = Azane| OtherNames = AmmoniaHydrogen nitrideSpirit of hartshorn
Nitrosil
Vaporole Ammonia data at NIST Webbook, last accessed May 7 2007.| Section1 = {{Chembox Identifiers| CASNo = 7664-41-7| PubChem = 222| SMILES = N| InChI = 1/H3N/h1H3| RTECS = BO0875000-->| Section2 = {{Chembox Properties| Formula = NH3| MolarMass = 17.0306 g/mol| Appearance = Colorless gas with strong pungent odor| Density = 0.6942 NIST Chemistry WebBook (website page of the National Institute of Standards and Technology) URL last accessed May 15 2007| MeltingPt = -77.73 °C (195.42 Kelvin)| Melting_notes =| BoilingPt = -33.34 °C (239.81 K)| Boiling_notes =| Solubility = 89.9 g/100 Milliliter at 0 °Celsius| SolubleOther =| Solvent =| pKa = 36 (ionization to NH2-)| pKa = 9.25 (formation of NH4+)| RefractIndex = Dielectric constant-->| Section3 = {{Chembox Structure| MolShape = Terminus| Dipole = 1.42 Debye-->| Section7 = {{Chembox Hazards| MainHazards = Hazardous gas, caustic, corrosive| NFPA-H = 3| NFPA-F = 1| NFPA-R =| NFPA-O =| RPhrases = , , , , , ,
, | SPhrases =| RSPhrases =| FlashPt = None MSDS Sheet from W.D. Service Co.| Autoignition = 651 °C| ExploLimits =| PEL = -->| Section8 = {{Chembox Related| OtherAnions = ammonium hydroxide (NH4OH)| OtherCations = Ammonium (NH4+)] (NH4Cl)| Function =| OtherCpds = Hydrazine
Hydrazoic acid
Hydroxylamine
Chloramine -->-->Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor. Ammonia contributes significantly to the nutritional needs of the planet as a precursor to foodstuffs and fertilizers. Ammonia, either directly or indirectly, is a building block for the synthesis of most pharmaceuticals. Although it is in wide use, ammonia is caustic and hazardous.

Ammonia used commercially is usually named anhydrous ammonia. This term emphasizes the absence of water. Because NH3 boils at -33 °C, the liquid must be stored under pressure or at low temperature. Its heat of vaporization is, however, sufficiently high that NH3 can be readily handled in ordinary beakers in a fume hood. "Household ammonia" or "ammonium hydroxide" is a solution of NH3 in water. The strength of such solutions is measured in units of baume (density), with 26 degrees baume (about 30 weight percent ammonia at 15.5 °C) being the typical high concentration commercial product. Ammonium hydroxide physical properties Household ammonia ranges in concentration from 5 to 10 weight percent ammonia. See Baumé scale.

Structure and basic chemical properties The ammonia molecule has a Trigonal pyramid (chemistry) shape, as predicted by VSEPR theory. The nitrogen atom in the molecule has a Lone pair, and ammonia acts as a Base (chemistry), a proton acceptor. This shape gives the molecule an overall dipole moment and makes it Polar molecule so that ammonia readily dissolves in Water (molecule). In water, a very small percentage of NH3 is converted into the ammonium cation (NH4+). Thus, the term ammonium hydroxide is a misnomer. The degree to which ammonia forms the ammonium ion increases upon lowering the pH of the solution— at "physiological" pH (~7), about 99% of the ammonia molecules are Protonation. Temperature and salinity also affect the proportion of NH4+. NH4+ has the shape of a regular tetrahedron.

The main uses of ammonia are in the production of fertilizers, explosives, and organic synthesis of organonitrogen compounds. It is also the active ingredient in household glass cleaners. Ammonia is found in small quantities in the atmosphere, being produced from the putrefaction of nitrogenous animal and vegetable matter. Ammonia and ammonium salts are also found in small quantities in rainwater, whereas ammonium chloride (sal-ammoniac), and ammonium sulfate are found in volcanic districts; crystals of ammonium bicarbonate have been found in Patagonian guano. The kidneys secrete NH3 to neutralize excess acid. electrolytes and the urine anion and osmolar gaps. Ammonium salts also are found distributed through all fertile soil and in seawater. Substances containing ammonia, or those that are similar to it, are called ammoniacal.

History Salts of ammonia have been known from very early times; thus the term Hammoniacus sal Webmineral website URL last accessed August 27 2006 appears in the writings of Pliny the Elder, although it is not known whether the term is identical with the more modern sal-ammoniac.

In the form of sal-ammoniac, ammonia was known to the alchemy as early as the 13th century, being mentioned by Albertus Magnus. Absolouteastronomy.com URL last accessed April 24 2006 It was also used by dyers in the Middle Ages in the form of fermented urine to alter the colour of vegetable dyes. In the 15th century, Basilius Valentinus showed that ammonia could be obtained by the action of alkalis on sal-ammoniac. At a later period, when sal-ammoniac was obtained by distilling the hoofs and horns of oxen and neutralizing the resulting carbonate with hydrochloric acid, the name "spirit of hartshorn" was applied to ammonia.

Gaseous ammonia was first isolated by Joseph Priestley in 1774 and was termed by him alkaline air; however it was acquired by the alchemist Basil Valentine. Abraham, Lyndy. Marvell and alchemy. Aldershot Scolar 1990. Eleven years later in 1785, Claude Louis Berthollet ascertained its composition.

The Haber process to produce ammonia from the nitrogen in the air was developed by Fritz Haber and Carl Bosch in 1909 and patented in 1910. It was first used on an industrial scale by the Germans during World War I, BBC.co.uk URL last accessed April 24 2006 following the allied blockade that cut off the supply of nitrates from Chile. The ammonia was used to produce explosives to sustain their war effort.Smith, Roland. Conquering Chemistry 2001

Synthesis and production Because of its many uses, ammonia is one of the most highly-produced inorganic chemicals. Dozens of chemical plants worldwide produce ammonia. The worldwide ammonia production in 2004 was 109 million metric tonnes. United States Geological Survey publication The People's Republic of China produced 28.4% of the worldwide production followed by India with 8.6%, Russia with 8.4%, and the United States with 8.2%. About 80% or more of the ammonia produced is used for fertilizing agricultural crops.

Before the start of World War I, most ammonia was obtained by the dry distillation Nobel Prize in Chemistry (1918) - Haber process. URL last accessed April 24 2006 of nitrogenous vegetable and animal waste products, including camel manure, where it was distillation by the reduction of nitrous acid and nitrites with hydrogen; in addition, it was produced by the distillation of coal, and also by the decomposition of ammonium salts by alkaline hydroxides BBC.co.uk URL last accessed April 24 2006 such as calcium oxide, the salt most generally used being the chloride (ammonium chloride) thus:

:2 NH4Cl + 2 CaO → CaCl2 + Ca(OH)2 + 2 NH3

Today, the typical modern ammonia-producing plant first converts natural gas (i.e., methane) or liquified petroleum gas (such gases are propane and butane) or petroleum naphtha into gaseous hydrogen. Starting with a natural gas feedstock, the processes used in producing the hydrogen are:

:H2 + RSH → RH + H2S(g)

:H2S + ZnO → ZnS + H2O

:CH4 + H2O → CO + 3 H2

:CO + H2O → CO2 + H2



:CO + 3 H2 → CH4 + H2O :CO2 + 4 H2 → CH4 + 2 H2O



:3 H2 + N2 → 2 NH3

The steam reforming, shift conversion, carbon dioxide removal and methanation steps each operate at absolute pressures of about 25 to 35 Bar (unit), and the ammonia synthesis loop operates at absolute pressures ranging from 60 to 180 bar, depending upon which proprietary design is used. There are many engineering and construction companies that offer proprietary designs for ammonia synthesis plants. Haldor Topsoe of Denmark, Lurgi AG of Germany, ThyssenKrupp of Germany, and Kellogg, Brown and Root of the United States are among the most experienced companies in that field. Kellogg Brown's Ammonia Process URL last accessed April 24 2006

As the availability and usage of fossil fuel become problematic (see peak oil and climate change), the hydrogen needed for ammonia synthesis can be obtained from electrolysis or thermal chemical cracking of water. In such case, the heat needed for thermal cracking can be obtained from nuclear reaction, while the electricity needed for electrolysis can be obtained from various renewable energy sources such as Wind turbine, Photovoltaics, hydroelectricity, and various forms of ocean energy especially that of OTEC.

Biosynthesis In certain organisms, ammonia is produced from atmospheric N2 by enzymes called nitrogenases. The overall process is called nitrogen fixation. Although it is unlikely that biomimetic methods will be developed that are competitive with the Haber process, intense effort has been directed toward understanding the mechanism of biological nitrogen fixation. The scientific interest in this problem is motivated by the unusual structure of the active site of the enzyme, which consists of an Fe7MoS9 ensemble.

Ammonia is also a metabolic product of amino acid deamination. In humans, it is quickly converted to urea, which is much less toxic. This urea is a major component of the dry weight of urine.

Properties Ammonia is a colorless gas with a characteristic pungent smell similar to human urine, as the urine contains an amount of ammonia in it. It is lighter than air, its density being 0.589 times that of Earth's atmosphere. It is easily liquefied due to the strong hydrogen bonding between molecules; the liquid boils at -33.3 °C, and solidifies at -77.7 °C to a mass of white crystals. Liquid ammonia possesses strong ionizing powers (Dielectric constant = 22), and solutions of salts in liquid ammonia have been much studied. Liquid ammonia has a very high standard enthalpy change of vaporization (23.35 Joule/mol, cf. water (molecule) 40.65 kJ/mol, methane 8.19 kJ/mol, phosphine 14.6 kJ/mol) and can therefore be used in laboratories in non-insulated vessels at room temperature, even though it is well above its boiling point.

It is miscible with water. All the ammonia contained in an aqueous solution of the gas may be expelled by boiling. The water solution of ammonia is Base (chemistry). The maximum concentration of ammonia in water (a saturation (chemistry) solution) has a density of 0.880 g /cubic centimetre and is often known as '.880 Ammonia'. Ammonia does not burn readily or sustain combustion, except under narrow fuel to air mixtures from 15-25% air. When mixed with oxygen, it burns with a pale yellowish-green flame. At high temperature and in the presence of a suitable catalyst, ammonia is decomposed into its constituent elements. Chlorine catches fire when passed into ammonia, forming nitrogen and hydrochloric acid; unless the ammonia is present in excess, the highly explosive nitrogen trichloride (NCl3) is also formed.

The ammonia molecule readily undergoes nitrogen inversion at room temperature - that is, the nitrogen atom passes through the plane of symmetry of the three hydrogen atoms; a useful analogy is an umbrella turning itself inside out in a strong wind. The energy barrier to this inversion is 24.7 kJ/mol in ammonia, and the resonance frequency is 23.79 Hertz, corresponding to microwave radiation of a wavelength of 1.260 cm. The absorption at this frequency was the first Microwave spectroscopy to be observed.C. E. Cleeton & N. H. Williams, 1934 - Online version; archive. URL last accessed May 8, 2006

Formation of salts One of the most characteristic properties of ammonia is its power of combining directly with acids to form salts; thus with hydrochloric acid it forms ammonium chloride (sal-ammoniac); with nitric acid, ammonium nitrate, etc. However perfectly dry ammonia will not combine with perfectly dry hydrogen chloride, a gas, moisture being necessary to bring about the reaction.Baker, H. B. (1894). J. Chem. Soc. 65: 612. :NH3 + Hydrochloric acid → Ammonium chloride

The salts produced by the action of ammonia on acids are known as the :Category:Ammonium compounds and all contain the ammonium ion (NH4+).

Acidity Although ammonia is well-known as a base, it can also act as an extremely weak acid. It is a protic substance, and is capable of dissociation into the amide (NH2−) ion, for example when solid lithium nitride is added to liquid ammonia, forming a lithium amide solution:

:Li3N(s)+ 2 NH3 (l) → 3 Li+(am) + 3 NH2−(am)

This is a Brønsted-Lowry acid-base reaction in which ammonia is acting as an acid.

Formation of other compounds Ammonia can act as a nucleophile in Nucleophilic substitution reactions. Amines can be formed by the reaction of ammonia with alkyl halides, although the resulting –NH2 group is also nucleophilic and secondary and tertiary amines are often formed as by-products. Using an excess of ammonia helps minimise multiple substitution, and neutralises the hydrogen halide formed. Methylamine is prepared commercially by the reaction of ammonia with chloromethane, and the reaction of ammonia with 2-bromopropanoic acid has been used to prepare racemic alanine in 70% yield. Ethanolamine is prepared by a ring-opening reaction with ethylene oxide: the reaction is sometimes allowed to go further to produce diethanolamine and triethanolamine.

Amides can be prepared by the reaction of ammonia with a number of carboxylic acid derivatives. Acyl chlorides are the most reactive, but the ammonia must be present in at least a twofold excess to neutralise the hydrogen chloride formed. Esters and anhydrides also react with ammonia to form amides. Ammonium salts of carboxylic acids can be Dehydration to amides so long as there are no thermally sensitive groups present: temperatures of 150–200 °C are required.

The hydrogen in ammonia is capable of replacement by metals, thus magnesium burns in the gas with the formation of magnesium nitride Mg3N2, and when the gas is passed over heated sodium or potassium, sodamide, NaNH2, and potassamide, KNH2, are formed. Where necessary in IUPAC nomenclature, IUPAC recommendations prefer the name azane to ammonia: hence chloramine would be named chloroazane in substitutive nomenclature, not chloroammonia.

Ammonia as a ligand of the tetraamminecopper(II) cation, 2+

]

Ammonia can act as a ] in transition metal complex (chemistry). It is a pure σ-donor, in the middle of the spectrochemical series, and shows intermediate HSAB concept behaviour. For historical reasons, ammonia is named ammine in the nomenclature of coordination compounds. Some notable ammine complexes include:

Ammine complexes of chromium(III) were known in the late 19th century, and formed the basis of Alfred Werner's theory of coordination compounds. Werner noted that only two isomers (fac- and mer-) of the complex could be formed, and concluded that the ligands must be arranged around the metal ion at the wikt:vertex of an octahedron. This has since been confirmed by X-ray crystallography.

An ammine ligand bound to a metal ion is markedly more acidic than a free ammonia molecule, although deprotonation in aqueous solution is still rare. One example is the Mercury(I) chloride, where the resulting amidomercury(II) compound is highly insoluble. :Hg2Cl2 + 2 NH3 → Hg + HgCl(NH2) + NH4+ + Cl−

Uses Nitric Acid production The most important single use of ammonia is in the production of nitric acid. A mixture of one part ammonia to nine parts air is passed over a platinum gauze catalyst at 850 °C, whereupon the ammonia is oxidisation to nitric oxide.

:4 NH3 + 5 O2 → 4 NO + 6 H2O :2 NO + O2 → 2 NO2 :2 NO2 + 2 H2O → 2 HNO3 + H2

The catalyst is essential, as the normal oxidation (or combustion) of ammonia gives Nitrogen and water: the production of nitric oxide is an example of kinetic control. As the gas mixture cools to 200–250 °C, the nitric oxide is in turn oxidized by the excess of oxygen present in the mixture, to give nitrogen dioxide. This is reacted with water to give nitric acid for use in the production of fertilizers and explosives.

Universal Indicator Ammonia solution is also used as universal indicator that could be used to test for different gases that require a universal indicator solution to show the gases were present.

Fertilizer In addition to serving as a fertilizer ingredient, ammonia can also be used directly as a fertilizer by forming a solution with irrigation water, without additional chemical processing. This later use allows the continuous growing of nitrogen dependent crops such as maize (corn) without agriculture rotation but this type of use leads to poor soil health.

Refrigeration Ammonia's thermodynamic properties made it one of the refrigerants commonly used in refrigeration units prior to the discovery of dichlorodifluoromethane Dichlorodifluoromethane by Aaron Vorderstrasse, Western Oregon University. in 1928, also known as Freon or R12.

But ammonia is toxic, gaseous, irritant, and corrosive to copper alloys, and over a kilo is needed for even a miniature fridge. With an ammonia refrigerant, the ever present risk of an escape brings with it a risk to life. However data on ammonia escapes has shown this to be an extremely small risk in practice, and there is consequently no control on the use of ammonia refrigeration in densely populated areas and buildings in almost all jurisdictions in the world.

Its use in domestic refrigeration has been mostly replaced by CFCs and HFCs in the first world, which are more or less non-toxic and non-flammable, and butane and propane in the 3rd world, which despite their high flammable do not seem to have produced any significant level of accidents. Ammonia has continued to be used for miniature and multifuel fridges, such as minibars and caravan fridges.

These ammonia absorption cycle domestic refrigerators do not use compression and expansion cycles, but are driven by temperature differences. However the energy efficiency of such refrigerators is relatively low. Today the smallest refrigerators mostly use solid state peltier thermopile heat pumps rather than the ammonia absorption cycle.

Ammonia continues to be used as a refrigerant in large industrial processes such as bulk icemaking and industrial food processing. Since the implication of haloalkanes being major contributors to ozone depletion, ammonia is again seeing increasing use as a refrigerant.

Disinfectant It is also sometimes added to drinking water along with chlorine to form chloramine, a disinfectant. Unlike chlorine on its own, chloramine does not combine with organic (carbon containing) materials to form carcinogenic halomethanes such as chloroform. However, chlorine and ammonia should never be mixed in an uncontrolled environment because they cause a chemical reaction that releases toxic gas. See Ammonia#Safety precautions for more information.

Fuel Liquid ammonia was used as the fuel of the rocket airplane, the X-15. Although not as powerful as other fuels, it left no soot in the reusable rocket engine, and has about the same density as the oxidizer, liquid oxygen, which simplified the aircraft's keeping the same center of gravity in flight. Anhydrous ammonia is a practical clean (Carbon dioxide-free) and renewable fuel which can be and has been used to replace fossil fuel in powering internal combustion engines.http://www.energy.iastate.edu/becon/ammonia.html In 1981 a Canadian company converted a 1981 Chevrolet Impala to run on an ammonia fuel.http://www.youtube.com/watch?v=L0hBAz6MxC4http://www.gregvezina.com

Cigarettes During the 1960s, tobacco companies such asBrown & Williamson and Philip Morris began using ammonia in cigarettes. The addition of ammonia serves to enhance the delivery of nicotine into the blood stream. As a result, the reinforcement effect of the nicotine was enhanced, increasing its addictive ability without actually increasing the portion of nicotine.Alix M. Freedman, " 'Impact Booster': Tobacco Firm Shows How Ammonia Spurs Delivery of Nicotine", The Wall Street Journal, Dec. 28, 1995.

Ammonia's role in biologic systems and human disease Ammonia is an important source of nitrogen for living systems. Although atmospheric nitrogen abounds, few living creatures are capable of utilizing this nitrogen. Nitrogen is required for the synthesis of amino acids, which are the building blocks of protein. Some plants rely on ammonia and other nitrogenous wastes incorporated into the soil by decaying matter. Others, such as nitrogen-fixing legumes, benefit from symbiosis relationships with rhizobia which create ammonia from atmospheric nitrogen.M.B. Adjei, K.H. Quesenberry and C.G. Chamblis. Nitrogen Fixation and Inoculation of Forage Legumes University of Florida IFAS Extension June 2002.

Ammonia also plays a role in both normal and abnormal animal physiology. Ammonia is created through normal amino acid metabolism and is toxic in high concentrations. PubChem Substance Summary, last accessed May 7 2007 The liver converts ammonia to urea through a series of reactions known as the urea cycle. Liver dysfunction, such as that seen in cirrhosis, may lead to elevated amounts of ammonia in the blood (hyperammonemia). Likewise, defects in the enzymes responsible for the urea cycle, such as ornithine transcarbamylase, lead to hyperammonemia. Hyperammonemia contributes to the confusion and coma of hepatic encephalopathy as well as the neurologic disease common in people with urea cycle defects and organic acidurias.Zschocke, Johannes, and Georg Hoffman. Vademecum Metabolism. Friedrichsdorf, Germany: Milupa GmbH, 2004.

Ammonia is important for normal animal acid/base balance. After formation of ammonium from glutamine, α-ketoglutarate may be degraded to produce two molecules of bicarbonate which are then available as buffers for dietary acids. Ammonium is excreted in the urine resulting in net acid loss. Ammonia may itself diffuse across the renal tubules, combine with a hydrogen ion, and thus allow for further acid excretion.Rose, Burton, and Helmut Rennke. Renal Pathophysiology. Baltimore, Maryland: Williams & Wilkins, 1994.

Theoretical role in alternative biochemistry Ammonia has been proposed as a possible replacement for water as a bodily solvent in the theoretical alternative biochemistries of lifeforms that do not use carbon for cellular structure and water as a solvent to dissolve bodily solutes and allow essential parts of metabolic processes to occur. It is suggested that ammonia would be most favorable for lifeforms that live in temperatures lower than the freezing point of water.Lazio, Joseph, Why do we assume that other beings must be based on carbon? Why couldn't organisms be based on other substances? sci.astro, ET Life (Astronomy Frequently Asked Questions). Retrieved on 2007-04-27.

Liquid ammonia as a solvent See also: Inorganic nonaqueous solvent Liquid ammonia is the best-known and most widely studied non-aqueous ionizing solvent. Its most conspicuous property is its ability to dissolve alkali metals to form highly coloured, electrically conducting solutions containing solvated electrons. Apart from these remarkable solutions, much of the chemistry in liquid ammonia can be classified by analogy with related reactions in aqueous solutions. Comparison of the physical properties of NH3 with those of water shows that NH3 has the lower melting point, boiling point, density, viscosity, dielectric constant and electrical conductivity; this is due at least in part to the weaker H bonding in NH3 and the fact that such bonding cannot form cross-linked networks since each NH3 molecule has only 1 lone-pair of electrons compared with 2 for each H2O molecule. The ionic self-dissociation constant of liquid NH3 at −50 °C is approx. 10-33 mol2·l-2.

Solubility of salts {||-!  ! Solubility (g of salt per 100 g liquid NH3)|-| Ammonium acetate| 389.6|-| [Lithium nitrate| 97.6|-| [Potassium nitrate| 0.35|-| [Sodium chloride| 138.0|-| [Sodium iodide| 205.5|-|}

Liquid ammonia is an ionizing solvent, although less so than water, and dissolves a range of ionic compounds including many [nitrates, nitrites, cyanides and thiocyanates. Most ammonium salts are soluble, and these salts act as acids in liquid ammonia solutions. The solubility of halide salts increases from fluoride to iodide. A saturated solution of ammonium nitrate contains 0.83 mol solute per mole of ammonia, and has a vapour pressure of less than 1 bar even at 25 °C.

Solutions of metals See also: Solvated electron, metallic solution Liquid ammonia will dissolve the alkali metals and other Electronegativity metals such as calcium, strontium, barium, europium and ytterbium. At low concentrations (Anhydrous ammonia is classified as toxic (T) and dangerous for the environment (N). The gas is flammable (autoignition temperature: 651 °C) and can form explosive mixtures with air (16–25%). The permissible exposure limit (PEL) in the United States is 50 Parts per million (35 mg/m3), while the IDLH concentration is estimated at 300 ppm. Repeated exposure to ammonia lowers the sensitivity to the smell of the gas: normally the odour is detectable at concentrations of less than 0.5 ppm, but desensitized individuals may not detect it even at concentrations of 100 ppm. Anhydrous ammonia corrodes copper (element)- and zinc (element)-containing alloys, and so brass fittings should not be used for handling the gas. Liquid ammonia can also attack rubber and certain plastics.

Ammonia reacts violently with the halogens, and causes the explosive polymerization of ethylene oxide. It also forms explosive compounds with compounds of gold (element), silver, Mercury (element), germanium or tellurium, and with stibine. Violent reactions have also been reported with acetaldehyde, hypochlorite solutions, potassium ferricyanide and peroxides.

Safety The U. S. Occupational Safety and Health Administration has set a 15-minute exposure limit for gaseous ammonia of 35 ppm by volume in the environmental air and an 8-hour exposure limit of 25 ppm by volume. Toxic FAQ Sheet for Ammonia published by the Agency for Toxic Substances and Disease Registry (ATSDR), September 2004 Exposure to very high concentrations of gaseous ammonia can result in lung damage and death. Although ammonia is regulated in the United States as a non-flammable gas, it still meets the definition of a material that is toxic by inhalation and requires a hazardous safety permit when transported in quantities greater than 13,248 L (3,500 gallons). Hazardous Materials (HM) Safety Permits from the website of the United States Department of Transportation (DOT)

See also

References

Bibliography

External links





Ammonia - Wikipedia, the free encyclopedia
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The Haber Process for the manufacture of ammonia
A description of the Haber Process and an explanation of the conditions used in terms of the position of equilibrium, the rate of the reaction and the economics of the process.

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Ammonia Workshop Edinburgh 2006
Enter your description here. ... Venue . Scottish Executive Victoria Quay Edinburgh, UK 4-6 December 2006 Organisation

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Ammonia (NH 3) is a colourless pungent gas that is familiar to us as the smell of urine. In fact probably no other compound can be identified by its smell and correctly named by as ...

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Contact: CEH Edinburgh are engaged in monitoring both gaseous ammonia (NH3) and a number of air pollutants with which it reacts. The monitoring of NH3 and aerosol ammonium (NH4 ...

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