Ammonia - Properties

Ammonia is a colourless gas with a characteristic pungent smell; it is lighter than air, its density being 0.589 times that of air. It is easily liquefied and the liquid boils at -33.7 °C, and solidifies at -75 °C to a mass of white crystals. Liquid ammonia possesses strong ionizing powers (ε = 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 kJ/mol, c.f. water 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 thou ...

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Ammonia, Ammonia - History, Ammonia - Production, Ammonia - Properties, Ammonia - Formation of salts, Ammonia - Acidity, Ammonia - Formation of other compounds, Ammonia - Ammonia as a ligand, Ammonia - Uses, Ammonia - Liquid ammonia as a solvent, Ammonia - Solubility of salts, Ammonia - Solutions of metals, Ammonia - Redox properties of liquid ammonia, Ammonia - Detection and determination, Ammonia - Safety precautions, Ammonia - Toxicity, Ammonia - Household use, Ammonia - Laboratory use of ammonia solutions, Ammonia - Laboratory use of anhydrous ammonia gas or liquid, Ammonia - Reference, Ammonia - Bibliography

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Ammonia is a compound of nitrogen and hydrogen with the formula NH3. At standard temperature and pressure ammonia is a gas. It is toxic and corrosive to some materials, and has a characteristic pungent odor. An ammonia molecule is not flat, but has the shape of a compressed tetrahedron known as a trigonal pyramid, as would be expected from VSEPR theory. This shape gives the molecule an overall dipole moment and makes it polar so that ammonia very readily dissolves in water. The nitrogen atom in the molecule has a lon ...

Including:

• Ammonia - History
• Ammonia - Production
• Ammonia - Properties
• Ammonia - Acidity
• Ammonia - Formation of other compounds
• Ammonia - Ammonia as a ligand
• Ammonia - Uses
• Ammonia - Liquid ammonia as a solvent
• Ammonia - Solubility of salts
• Ammonia - Solutions of metals
• Ammonia - Redox properties of liquid ammonia
• Ammonia - Detection and determination
• Ammonia - Safety precautions
• Ammonia - Toxicity
• Ammonia - Household use
• Ammonia - Laboratory use of ammonia solutions
• Ammonia - Laboratory use of anhydrous ammonia gas or liquid
• Ammonia - Reference
• Ammonia - Bibliography

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Ammonia - Toxicity. The toxicity of ammonia solutions does not usually cause problems for humans and other mammals, as a specific mechanism exists to prevent its build-up in the bloodstream. Ammonia is converted to carbamoyl phosphate by the enzyme carbamoyl phosphate synthase, and then enters the urea cycle to be either incorporated into amino acids or excreted in the urine. However fish and amphibians lack this mechanism, as they can usually eliminate ammonia from their bodies by direct excretion. Ammonia even at dilute concentrations is highly toxic to aquatic animals, and for this reason it is class ...

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Ammonia, Ammonia - History, Ammonia - Production, Ammonia - Properties, Ammonia - Formation of salts, Ammonia - Acidity, Ammonia - Formation of other compounds, Ammonia - Ammonia as a ligand, Ammonia - Uses, Ammonia - Liquid ammonia as a solvent, Ammonia - Solubility of salts, Ammonia - Solutions of metals, Ammonia - Redox properties of liquid ammonia, Ammonia - Detection and determination, Ammonia - Safety precautions, Ammonia - Toxicity, Ammonia - Household use, Ammonia - Laboratory use of ammonia solutions, Ammonia - Laboratory use of anhydrous ammonia gas or liquid, Ammonia - Reference, Ammonia - Bibliography

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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, ...

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Ammonia, Ammonia - History, Ammonia - Production, Ammonia - Properties, Ammonia - Formation of salts, Ammonia - Acidity, Ammonia - Formation of other compounds, Ammonia - Ammonia as a ligand, Ammonia - Uses, Ammonia - Liquid ammonia as a solvent, Ammonia - Solubility of salts, Ammonia - Solutions of metals, Ammonia - Redox properties of liquid ammonia, Ammonia - Detection and determination, Ammonia - Safety precautions, Ammonia - Toxicity, Ammonia - Household use, Ammonia - Laboratory use of ammonia solutions, Ammonia - Laboratory use of anhydrous ammonia gas or liquid, Ammonia - Reference, Ammonia - Bibliography

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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 oxidized to nitric oxide. 4NH3 + 5O2 → 4NO + 6H2O The catalyst is essential, as the normal oxidation (or combustion) of ammonia gives dinitrogen and water: the production of nitric oxide is an example of kinetic control. As the gas mixture cools to 200–250 ...

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Ammonia, Ammonia - History, Ammonia - Production, Ammonia - Properties, Ammonia - Formation of salts, Ammonia - Acidity, Ammonia - Formation of other compounds, Ammonia - Ammonia as a ligand, Ammonia - Uses, Ammonia - Liquid ammonia as a solvent, Ammonia - Solubility of salts, Ammonia - Solutions of metals, Ammonia - Redox properties of liquid ammonia, Ammonia - Detection and determination, Ammonia - Safety precautions, Ammonia - Toxicity, Ammonia - Household use, Ammonia - Laboratory use of ammonia solutions, Ammonia - Laboratory use of anhydrous ammonia gas or liquid, Ammonia - Reference, Ammonia - Bibliography

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Salts of ammonia have been known from very early times; thus the term Hammoniacus sal appears in the writings of Pliny, 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 alchemists as early as the 13th century, being mentioned by Albertus Magnus. 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 ...

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Ammonia, Ammonia - History, Ammonia - Production, Ammonia - Properties, Ammonia - Formation of salts, Ammonia - Acidity, Ammonia - Formation of other compounds, Ammonia - Ammonia as a ligand, Ammonia - Uses, Ammonia - Liquid ammonia as a solvent, Ammonia - Solubility of salts, Ammonia - Solutions of metals, Ammonia - Redox properties of liquid ammonia, Ammonia - Detection and determination, Ammonia - Safety precautions, Ammonia - Toxicity, Ammonia - Household use, Ammonia - Laboratory use of ammonia solutions, Ammonia - Laboratory use of anhydrous ammonia gas or liquid, Ammonia - Reference, Ammonia - Bibliography

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Because of its many uses, ammonia is one of the most highly-produced inorganic chemicals. Before the start of WWI most ammonia was obtained by the dry distillation of nitrogenous vegetable and animal products; by the reduction of nitrous acid and nitrites with nascent hydrogen; and also by the decomposition of ammonium salts by alkaline hydroxides or by quicklime, the salt most generally used being the chloride (sal-ammoniac) thus 2NH4Cl + 2CaO → CaCl2 + Ca(OH)2See also:

Ammonia, Ammonia - History, Ammonia - Production, Ammonia - Properties, Ammonia - Formation of salts, Ammonia - Acidity, Ammonia - Formation of other compounds, Ammonia - Ammonia as a ligand, Ammonia - Uses, Ammonia - Liquid ammonia as a solvent, Ammonia - Solubility of salts, Ammonia - Solutions of metals, Ammonia - Redox properties of liquid ammonia, Ammonia - Detection and determination, Ammonia - Safety precautions, Ammonia - Toxicity, Ammonia - Household use, Ammonia - Laboratory use of ammonia solutions, Ammonia - Laboratory use of anhydrous ammonia gas or liquid, Ammonia - Reference, Ammonia - Bibliography

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