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| General | |
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| Chemical formula | 3}} |
| Molecular weight | 17.03 amu |
| Appearance | colorless gas |
| CAS number | 7664-41-7 |
| MSDS | MSDS |
| Other names | |
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| Physical properties | |
| Density and phase at STP | ? g/ cm3 (gas) |
| Solubility | miscible with water |
| Specific gravity | 0.63 |
| Crystal structureIn mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. A crystal structure is composed of a unit cell a set of atoms arranged in a particular way, which is periodically repeated in three dimensions on a latti | ? |
| pHAlternate uses: see Ph pH (potential (of) hydrogen) is a measure of the concentration of hydrogen ions (H+) in a solution and, therefore, its acidity or alkalinity. The concept was introduced by S. Sorensen in 1909. The p stands for the German potenz mean (10% solution in water) (pKa) | 12 |
| Thermal decomposition | ? K (? °C) |
| Phase behavior | |
| Melting pointThe melting point of a solid is the temperature at which it changes state from solid to liquid. When considered as the temperature of the reverse change, it is referred to as the freezing point . For example, the melting point of the element mercury is 23 | 195 KThe kelvin (symbol: K is the SI unit of temperature, and is one of the seven SI base units. It is defined by two facts: zero kelvin is absolute zero (when molecular motion stops), and one kelvin is the fraction 1/273. 16 of the thermodynamic temperature o (-78 ° CThe degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius ( 1701 1744), who first proposed it in 1742. The Celsius temperature scale was designed so that the freezing point of water is 0 degrees, and the boiling po) |
| Boiling pointAlternate use: Boiling Point, English title of Kitano Takeshi's film 3-4X Jugatsu The boiling point of a substance is the temperature at which it can change state from a liquid to a gas throughout the bulk of the liquid. A liquid may change to a gas at te | 240 K (-33 °C) |
| Triple pointIn physics, the triple point of a substance is the temperature and pressure at which three phases ( gas, liquid, and solid) of that substance may coexist in thermodynamic equilibrium. For example, the triple point temperature of water is exactly 273. | ? K (? °C) ? barThe bar is a measurement unit of pressure, equal to ten newtons per square centimetre. The word bar is of Greek origin, baros meaning weight. The preferred SI unit of pressure is the pascal (Pa), which is one newton per square metre. 1 bar is equal to 100 |
| Critical point | ? K (? °C) ? bar |
| Heat of fusion (ΔfusH) | ? kJ/ mol |
| Entropy of fusion (ΔfusS) | ? J/mol·K |
| Heat of vaporization (ΔvapH) | ? kJ/mol |
| Safety | |
| Ingestion | Dangerous. Symptoms include nausea and vomiting; damage to lips, mouth, and esophagus. |
| Inhalation | Vapours are extremely irritating and corrosive. |
| Skin | Concentrated solutions may produce severe burns and necrosis. |
| Eyes | May cause permanent damage, even in small quantities. |
| Flash point | 11 °C |
| Autoignition temperature | 651.1 °C |
| Explosive limits | 16 - 25% |
| OSHA Permissible Exposure Limit (PEL) | 50 ppm |
| NIOSH Immediate Danger to Life and Health (IDLH) | 500 ppm |
| Precautions | |
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| Solid properties | |
| Standard enthalpy change of formation (ΔfH0solid) | ? kJ/mol |
| Heat capacity (Cp) | ? J/mol·K |
| Density | ? g/cm3 |
| Liquid properties | |
| ΔfH0liquid | -40.2 kJ/mol |
| Cp | ? J/mol·K |
| Density | 8.0 g/cm3 |
| Gas properties | |
| ΔfH0gas | -45.9 kJ/mol |
| Standard molar entropy (S0gas) | 192.77 J/mol·K |
| Cp | ? J/mol·K |
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SI units and standard conditions used unless otherwise stated.
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Ammonia is a chemical compound with the formula N H }. The molecule is not flat, but has the shape of a flattened tetrahedron known as a trigonal pyramid. In solution it forms the positively charged ammonium ion N H } }, which has the shape of a regular tetrahedron.
At standard temperature and pressure, ammonia is a gas with a characteristic pungent smell. Its main uses are in the production of fertilizers, explosives and polymers. 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 without crop rotation but this type of use leads to poor soil health.
Ammonia is very well suited as a refrigerant, since it liquefies readily under pressure, and was used in virtually all refrigeration units prior to the advent of freons. This use was largely replaced in small refrigeration units by freons as these are not toxic irritants as is ammonia, while continuing in use in large industrial processes such as bulk icemaking and industrial food processing. Ammonia is also useful as a component in absorbtion-type refrigerators, which do not use compression and expansion cycles but can exploit heat differences. Since the implication of freons as major greenhouse gases during the 1990s, ammonia is again seeing increasing use as a refrigerant.
Ammonia is found in small quantities as the carbonate in the atmosphere, being produced from the putrefaction of nitrogenous animal and vegetable matter. Ammonium salts are also found in small quantities in rain-water, whilst ammonium chloride (sal-ammoniac) and ammonium sulfate are found in volcanic districts; and crystals of ammonium bicarbonate have been found in Patagonian guano. Ammonium salts also are found distributed through all fertile soil, in sea-water, and in most plant and animal liquids, and also in urine.
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