Chemical Fact Sheet
Nitrogen
| Chemical Abstract Number (CAS #) | 7727-37-9 |
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| Synonyms | MOL-NITROGEN-; NITROGEN-GAS-; NITROGEN-14; Azote- (French); Nitrogeno- (Spanish) |
| Analytical Methods | SM4500NH3 - SM4500NO2 - SM4500NO3 - SM4500NORG |
| Molecular Formula | N |
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Synopsis
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Nitrogen-(L.nitrum,Gr. nitron, native soda; genes, forming), N; at.wt. 14.00674(7); at.no. 7; m.p. -210.00 deg C; b.p. -195.8 deg C; density l.2506 g/l; sp. gr. liquid 0.808 (-195.8 deg C), solid 1.026 (-252 deg C); valence 3 or 5. Discovered by Daniel Rutherford in 1772, but Scheele, Cavendish, Priestley, and others about the same time studied "burnt or dephlogisticated air," as air without oxygen was then called. Nitrogen makes up 78% of the air, by volume. The atmosphere of Mars, by comparison, is 2.6% nitrogen. The estimated amount of this element in our atmosphere is more than 4000 trillion tons. From this inexhaustible source it can be obtained by liquefaction and fractional distillation. Nitrogen molecules give the orange-red, blue-green, blue-violet, and deep violet shades to the aurora. The element is so inert that Lavoisier named it azote, meaning without life, yet its compounds are so active as to be most important in foods, poisons, fertilizers, and explosives. Nitrogen can be also easily prepared by heating a water solution of ammonium nitrite. Nitrogen, as a gas, is colorless, odorless, and a generally inert element. As a liquid it is also colorless and odorless, and is similar in appearance to water. Two allotropic forms of solid nitrogen exist, with the transition from the alpha to the beta form taking place at -237 deg C. When nitrogen is heated, it combines directly with magnesium, lithium, or calcium; when mixed with oxygen and subjected to electric sparks, it forms first nitric oxide (NO) and then the dioxide (NO2); when heated under pressure with a catalyst with hydrogen, ammonia is formed (Haber process). The ammonia thus formed is of the utmost importance as it is used in fertilizers, and it can be oxidized to nitric acid (Ostwald process). The ammonia industry is the largest consumer of nitrogen. Large amounts of gas are also used by the electronics industry, which uses the gas as a blanketing medium during production of such components as transistors, diodes, etc. Large quantities of nitrogen are used in annealing, stainless steel and other steel mill products. The drug industry also uses large quantities. Nitrogen is used as a refrigerant both for the immersion freezing of food products and for transportation of foods. Liquid nitrogen is also used in missile work as a purge for components, insulators for space chambers, etc., and by the oil industry to build up great pressures in wells to force crude oil upward. Sodium and potassium nitrates are formed by the decomposition of organic matter with compounds of the metals present. In certain dry areas of the world these saltpeters are found in quantity. Ammonia, nitric acid, the nitrates, the five oxides (N2O, NO, N2O3, NO2, and N2O5), TNT, the cyanides, etc. are but a few of the important compounds. Nitrogen gas prices vary from 2 cents to $2.75 per 100 cu ft (2.83 cu. meters), depending on purity, etc. Production of elemental nitrogen in the U.S. is more than 9 million short tons per year. Natural nitrogen contains two isotopes, 14N and 15N. Ten other isotopes are known. |
| Use | IN MFR OF AMMONIA, NITRIC ACID, NITRATES, CYANIDES, ETC & EXPLOSIVES; IN FILLING HIGH TEMPERATURE THERMOMETERS, INCANDESCENT BULBS; TO FORM AN INERT ATMOSPHERE FOR PRESERVATION OF MATERIALS FOR USE IN DRY BOXES OR GLOVE BAGS; PHARMACEUTIC AID (AIR DISPLACEMENT); LIQ: IN FOOD FREEZING PROCESSES & IN LABORATORY AS A COOLANT. PRODN OF ACRYLONITRILE, CYANAMIDE, NITRIDES; IN TRANSIT FOOD REFRIGERATION; PRESSURIZING LIQ PROPELLANTS; CHILLING IN ALUMINUM FOUNDRIES; BRIGHT ANNEALING OF STEEL; CRYOGENIC PRESERVATION; SOURCE OF PRESSURE IN OIL WELLS; INFLATING TIRES; FOOD ANTIOXIDANT. IN PRODN OF NITROGEN FERTILIZER; FOR PUMPING & TRANSFER OF COMBUSTIBLE LIQ; LIQ USED IN OPERATIONS INVOLVING CREATION OF LOW TEMP (VACUUM APPARATUS, CRYOSTATS) GAS: AS NITROGEN FLUSH FOR FLAVOR ISOLATION. REFRIGERANT FOR CRYOPULVERIZATION-EG, OF PLASTICS-AS LIQ; CRYOGENIC AGENT IN STAINLESS STEEL DEFORMATION (AS LIQ); CRYOGENIC BEARING LUBRICANT IN ROCKET PROPULSION SYSTEMS; INERT GAS IN CHEM PROCESSING, EG, FOR PURGING; INERT ATM, EG, FOR HEAT TREATMENT OF METALS; INERT LIQ TO REMOVE IMPURITIES ON ELECTRONIC COMPONENTS; DILUENT TO CONTROL REACTION RATES IN POLYMER PROCESSING; PRESSURE STABILIZER IN ENHANCED OIL/NATURAL GAS RECOVERY. BLANKETING MEDIUM DURING PRODN OF TRANSISTORS, DIODES, ETC IN ELECTRONICS INDUSTRY; IN MISSILES AS PURGE FOR COMPONENTS, IN INSULATORS FOR SPACE CHAMBERS. DILUENT FOR MEDICINAL GASES. ISOTOPE (15)NITROGEN IN NUCLEAR REACTORS FOR THERMAL ENERGY NEUTRON CAPTURE. TO CRYOPUMP OR FREEZE RESIDUAL GASES IN SPACE-SIMULATION CHAMBERS; IN CRYOSURGERY; PRESERVATION OF WHOLE BLOOD, TISSUE, BONE MARROW, AND ANIMAL SEMEN. PHARMACEUTICALLY IT IS EMPLOYED TO REPLACE AIR IN CONTAINERS OF SUBSTANCES WHICH WOULD BE ADVERSELY AFFECTED BY AIR OXIDATION, EXAMPLES INCL ITS USE WITH FIXED OILS, CERTAIN VITAMIN PREPN, & A VARIETY OF INJECTABLE PRODUCTS. FOOD ADDITIVE: MEAT INSPECTION DIVISION, LIMITATIONS: TO EXCLUDE OXYGEN FROM SEALED CONTAINERS. Nitrogen has been used to euthanatize dogs, rabbits, and mink. Propellant, aerating agent, and gas. Free nitrogen is used in many industries as an inert medium for various chemical reactions, for the pumping and transfer of combustible liquids, for the measurement of high temperatures and for the purging of pipes and vessels that have contained chemicals, prior to filling with other chemicals, to carry out repair work, such as welding, and to entering for maintenance and inspection work. |
| Consumption Patterns | FOOD INDUSTRY, 24%; CHEMICALS, 20%; ELECTRONICS, 18%; LOW-TEMPERATURE SYSTEMS, 11%; METALS, 9%; OIL RECOVERY, 4%; INERT ATMOSPHERES, 3%; STEEL, 3%; OTHER, 8% (1979) Chemical and petroleum processing, 30%; metal refining and processing, 20%; electronics, 5%; low temperature application (food freezing), 20%; oil and gas production, 10%; misc, 15% (1981). |
| Apparent Color | COLORLESS GAS; COLORLESS LIQ; SOLID CUBIC CRYSTALS; *GAS CONDENSES TO LIQ; SOLIDIFIES TO SNOW-WHITE MASS |
| Odor | ODORLESS GAS |
| Boiling Point | -195.79 DEG C |
| Melting Point | -210.01 DEG C |
| Density | 0.808 @ -195.8 deg C (liquid); 1.026 @ -252 deg C (solid) |
| Sensitivity Data | The liquid may cause severe frostbite or burns to the skin. |
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Chemical and Physical Properties |
ATOMIC NUMBER: 7; VALENCES: 3, 5; ELEMENTAL STATE: N2; TWO NATURALLY OCCURRING ISOTOPES: 14 (99.635%), 15 (0.365%); FIVE SHORT-LIVED, ARTIFICIAL, RADIOACTIVE ISOTOPES: 12, 13, 16-18; CRITICAL DENSITY: 0.311 G/CU CM; HEAT OF DISSOCIATION OF NITROGEN MOLECULE (N2): 225.1 KCAL/MOLE TWO ALLOTROPIC FORMS OF SOLID NITROGEN EXIST, WITH TRANSITION FROM ALPHA TO BETA FORM TAKING PLACE @ -237 DEG C ATOMIC RADIUS: 0.70 A; IONIC (CRYSTAL) RADII: 1.32 A (-3 0XIDATION STATE); 0.27 A (+5 OXIDATION STATE); ELECTRONEGATIVITY (PAULING SCALE): 3.04; ORBITAL ELECTRONS: [HE]2S2-2P3 TRIPLE POINT TEMP: 63.1 DEG K; TRIPLE POINT PRESSURE: 0.127 ATM; HEAT OF FUSION: 6.1 CAL/G Specific Heat: 0.249 cal/g/deg K @ 25 deg C (N2) Ratio of specific heats of vapor (Gas): 1.3962 Critical compressibility factor= 0.2916. Critical volume: 3.216 cu dm/kg One mole of nitrogen /weighs/ 0.0280134 kg Diffusivities of nitrogen in other gases at 101.325 kPa in argon at 20 deg C is 0.194 sq cm/s; in carbon dioxide at 20 deg C is 0.163 sq cm/s; in helium at 20 deg C is 0.705 sq cm/s; in hydrogen at 0 deg C is 0.674 sq cm/s; in oxygen at 0 deg C is 0.181 sq cm/s. Velocity of sound in nitrogen at 101.325 kPa at 0 deg C: 336.96 m/s. Dielectric constant, liquid at 70.15 k= 1.454; dielectric constant, gas at 101.325 kPa at 20 deg C= 1.0005480 Liquid surface tension 8.3 dynes/cm= 0.083 N/m at -193 deg C. INERT GAS; DUE TO STABLE TRIPLE BOND STRUCTURE, NITROGEN MOLECULE SHOWS LITTLE ACTIVITY TOWARD OTHER ELEMENTS |
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Environmental Impact |
43,725 individuals exposed (est) from actual observed occupational use of nitrogen. |
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Environmental Fate |
CONSTITUTES ABOUT 75.5% BY WEIGHT OR 78.06% BY VOL OF ATMOSPHERE; FOUND FREQUENTLY IN VOLCANIC OR MINE GASES, GASES FROM SPRINGS & GASES OCCLUDED IN MINERALS & ROCKS FIXED OR COMBINED NITROGEN IS PRESENT IN MANY MINERAL DEPOSITS. |
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Disposal |
Release to atmosphere. |
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Alphabetical List of Compounds |
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List of Compounds by CAS Number |
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