Nitrogen

NITROGEN General Name, symbol, number

nitrogen, N, 7

Element category

nonmetal

Group, period, block

15, 2, p

Appearance

colorless gas

Standard atomicweight 14.0067(2) g·mol−1 Electron configuration 1s2 2s2 2p3 Electrons per shell

2, 5

Physical properties Phase

gas

Density

(0 °C, 101.325 kPa) 1.251 g/L

Melting point

63.15 K (-210.00 °C, -346.00 °F)

Boiling point

77.36 K (-195.79 °C, -320.3342 °F)

Critical point

126.19 K, 3.3978 MPa

Heat of fusion

(N2) 0.360 kJ·mol−1

Heat of vaporization

(N2) 5.56 kJ·mol−1

Specific heat capacity

(25 °C) (N2) 29.124 J·mol−1·K−1

Vapor pressure P/Pa

1

10

100

1k

10 k

100 k

at T/K

37

41

46

53

62

77

Atomic properties Crystal structure

hexagonal

Oxidation states

5, 4, 3, 2, 1,[1], -1, -3 (strongly acidic oxide)

Electronegativity

3.04 (Pauling scale)

Ionization energies (more)

1st: 1402.3 kJ·mol−1 2nd: 2856 kJ·mol−1 3rd: 4578.1 kJ·mol−1

Atomic radius

65 pm

Atomic radius (calc.)

56 pm

Covalent radius

75 pm

Van der Waals radius

155 pm Miscellaneous

Magnetic ordering

diamagnetic

Thermal conductivity

(300 K) 25.83 × 10−3 W·m−1·K−1

Speed of sound

(gas, 27 °C) 353 m/s

CAS registry number

7727-37-9

• • • • • •

Nitrogen was first discovered in 1772 by Daniel Rutherford, a Scottish physician and chemist. Elementary nitrogen constitutes three-forth of air by weight It is also abundant in the combined state as salpetre(KNO3),sodium nitrate (chile salpetre) and ammonium salts. Nitrogen (Latin nitrogenium, where nitrum (from Greek nitron) means "saltpetre" , and genes means "forming") is formally considered to have been discovered by Daniel Rutherford in 1772, who called it noxious air or fixed air. Nitrogen is an essential constituent of all vegetable and animal proteins

NITROGEN GROUP *The elements N , P, As, Sb, Bi , Uup Constitute the fifteenth group of periodic table.this group is called nitrogen group * This group consists of nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) and ununpentium (Uup) (unconfirmed) * The general E.C of the group is ns 2 np 3 *This group has the defining characteristic that all the component elements have 5 electrons in their outermost shell, that is 2 electrons in the s subshell and 3 unpaired electrons in the p subshell * These electrons are equally distributed as px1 py1 pz1 which correspond to half filled configuration *These elements are also noted for their stability in compounds due to their tendency for forming double and triple covalent bonds *When these substances react with various chemicals of the body, they create strong free radicals not easily processed by the liver, where they accumulate. Paradoxically it is this strong bonding which causes nitrogen and bismuth's reduced toxicity (when in molecules), as these form strong bonds with other atoms which are difficult to split, creating very unreactive molecules. For example N2, the diatomic form of nitrogen, is used for inert atmosphere in situations where argon or another noble gas would be prohibitively expensive *As we go round the group , the two electrons present in the valence s-orbitol becomes inert and only the three electrons present in the outer most p-orbitols are involved in chemical combinations

*this is known as inert pair effect * as we move from nitrogen to bismuth, the penta valency becomes less pronounced while trivalency becomes more pronounced

FIXATION OF NITROGEN IN NATURE * Nitrogen fixation is the process by which nitrogen is taken from its natural, relatively inert molecular form (N2) in the atmosphere and converted into nitrogen compounds (such as ammonia, nitrate and nitrogen dioxide).

MANUFACTURE OF AMMONIA • • • • • • • • • • •

Joseph priestly was the first one to prepare hydrogen in 1744 by heating slaked lime with sal ammonic Ammonia is an important chemical that is used to manufacture fertilizers such as ammonium sulphate, and ammonium phosphate. It is also used in the preparation of plastics, nylon etc; A mixture of nitrogen and hydrogen in the ratio 1:3 under pressure (200-900 atm) is passed over a catalyst finely divided iron and molybdenum as promoter,heated to about 770k N2 + 3H2 2NH3 The ammonia so manufactured can be oxidised to nitric oxide by passing a mixture of ammonia and air over heated platinum guaze at 1070k. Nitric oxide combines with more of oxygen to give nitrogen dioxide which when observed in water in the presence of exess of air, gives nitric acid(Ostwald’s process) 4NH3 + 5O2 4NO+6HO2 2NO+O2 2NO2 4NO2+2H20+O2 4HNO3 Ammonia and nitric acid manufactured above may be converted into ammonium salts and nitrates suitable as fertilizers.Thus these meathods of nitrogen fixation are of vital importance to the agriculturists.

NITROGEN FIXATION IN NATURE • • • •

Due to electrical disturbances atmospheric nitrogen and oxygen combine to give nitric oxide which gets further oxidised to nitrogen dioxide. This reacts with rain water in the presence of exess of oxygen to produce nitric acid and is washed down to earth. Here it reacts with bases of the soil to give nitrates. In addition to this certain bacteria living in the nodules on the routes of leguminous plants e.g. pea, beans, etc; convert nitrogen into nitrogenous compounds which can be directly assimilated by the plant.

NITROGEN CYCLE • • • • •

Ther is a continoul turnover of nitrogen between the atmosphere, the soil, the sea and living organisms. The nitrogen passes from atmosphere to plants and animals, converted into useful products like ammonia,nitric acid etc. And still its percentage in the atmosphere remains practically unchanged This is due to the fact that combined nitrogen is constantly passing back to the atmosphere. This cycle of changes involved is known as nitrogen cycle.

•

USES OF NITROGEN COMPOUNDS

• • • • • • • • • •

Liquid ammonia is used as solvent Ammonia is used as a refrigerant in ice plants Ammonia is used in the manufacture of artificial silk,urea,manures,washing soda etc; Nitrous oxide mixed with oxygen is used as anaesthetic for minor operations in dentidtry and surgery. Nitrous acid is used in the manufacture of azo-dyes. Nitric acid is used in the manufacture of fertilizers , explosives like TNT,GTN,etc. Nitric acid is used in the purification of gold and silver. Nitric acid is used in picking of stainless stell. Nitric acid is used in the manufacture of perfumes , artificial silk , medicine etc. Liquid nitrogen is used as a refrigerant.

Other uses: *Fertilizer Approximately 83% (as of 2003) of ammonia is used as fertilizers either as its salts or as solutions. Consuming more than 1% of all man-made power, the production of ammonia is a significant component of the world energy budget.

Precursor to nitrogenous compounds Ammonia is directly or indirectly the precursor to most nitrogen-containing compounds. Practically all synthetic and all inorganic nitrogen compounds are prepared from ammonia. An important derivative is nitric acid. This key material is generated via the Ostwald process by oxidisation of ammonia with air over a platinum catalyst at 700 - 850 °C, ~9 atm. Nitric oxide is an intermediate: NH3 + 2 O2 → HNO3 + H2O Nitric acid is used for the production of fertilizers, explosives, and natural organonitrogen other chemical compounds.

Minor and emerging uses Refrigeration - R717 Ammonia's thermodynamic properties made it one of the refrigerants commonly used prior to the discovery of dichlorodifluoromethane. Ammonia's toxicity complicates this application. Anhydrous ammonia is widely used in industrial refrigeration applications because of its high energy efficiency and low cost. Ammonia is used less frequently in commercial applications, such as in grocery store freezer cases and refrigerated displays due to its toxicity. For remediation of gaseous emissions

Ammonia used to scrub SO2 from the burning of fossil fuels, the resulting product is converted to ammonium sulfate for use as fertilizer. Ammonia neutralizes the nitrogen oxides (NOx) pollutants emitted by diesel engines. This technology, called SCR (selective catalytic reduction), relies on a vanadia-based catalyst. As a fuel Ammonia was used during World War II to power buses in Belgium, and in engine and solar energy applications prior to 1900. 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 its density approximately matches that for the oxidizer, liquid oxygen, which simplified the aircraft's design.

As a vehicle fuel Ammonia is proposed as a practical and clean alternative to fossil fuel for internal combustion engines. The biggest obstacle is the enormous increase in production required since present production, although the second most produced chemical, is a very small fraction of world petroleum usage. Ammonia has no more serious issues, as an alternative vehicle fuel compared to petrol or diesel, including toxicity, flammability, use in engines, pollution, energy density .It does require twice the storage volume of petrol/diesel. It can run in existing engines. It is already widely produced and distributed, and can be manufactured from renewable energy sources, coal or nuclear power. The main down side is that overall it is significantly less efficient than batteries. The 60 MW Rjukan dam in Telemark Norway, was producing ammonia via electrolysis of water for many years from 1913 producing fertilizer for much of Europe. Ammonia is already produced, transported and stored on a vast scale. In combination with coal gas it was used to run 20 buses on 8 routes covering many tens of thousands of miles with no injuries or engine damage.It can be used in existing engines with only minor modifications to carburetors / injectors. If produced from coal, the CO2 can be readily sequestrated. (the combustion products are nitrogen and water). In 1981 a Canadian company converted a 1981 Chevrolet Impala to operate using ammonia as fuel. The use of ammonia as fuel continues to be discussed. There are prototype solid state processes to use electricity to convert nitrogen and water directly to ammonia, which are claimed to be cheaper, more efficient and capable of much smaller scale application ie to otherwise stranded assets such as remote wind turbines. The calorific value of ammonia is 22.5 MJ/kg (9690 BTU/lb) which is about half that of diesel. In a normal engine, in which the water vapor is not condensed, the calorific value of ammonia will be about 21% less than this figure. Textile Liquid ammonia is used for treatment of cotton materials, give a properties like mercerisation using alkalies. And also used for pre-washing of wool. Poison treatment Solutions of ammonia in water can be applied on the skin to lessen the effects of acidic animal poisons, especially insect poison and jellyfish poison.

FIXATION OF NITROGEN IN NATURE * Nitrogen fixation is the process by which nitrogen is taken from its natural, relatively inert molecular form (N2) in the atmosphere and converted into nitrogen compounds (such as ammonia, nitrate and nitrogen dioxide).

MANUFACTURE OF AMMONIA • • • • • • • • • • •

Joseph priestly was the first one to prepare hydrogen in 1744 by heating slaked lime with sal ammonic Ammonia is an important chemical that is used to manufacture fertilizers such as ammonium sulphate, and ammonium phosphate. It is also used in the preparation of plastics, nylon etc; A mixture of nitrogen and hydrogen in the ratio 1:3 under pressure (200-900 atm) is passed over a catalyst finely divided iron and molybdenum as promoter,heated to about 770k N2 + 3H2 2NH3 The ammonia so manufactured can be oxidised to nitric oxide by passing a mixture of ammonia and air over heated platinum guaze at 1070k. Nitric oxide combines with more of oxygen to give nitrogen dioxide which when observed in water in the presence of exess of air, gives nitric acid(Ostwald’s process) 4NH3 + 5O2 4NO+6HO2 2NO+O2 2NO2 4NO2+2H20+O2 4HNO3 Ammonia and nitric acid manufactured above may be converted into ammonium salts and nitrates suitable as fertilizers.Thus these meathods of nitrogen fixation are of vital importance to the agriculturists.

NITROGEN FIXATION IN NATURE

• • • •

Due to electrical disturbances atmospheric nitrogen and oxygen combine to give nitric oxide which gets further oxidised to nitrogen dioxide. This reacts with rain water in the presence of exess of oxygen to produce nitric acid and is washed down to earth. Here it reacts with bases of the soil to give nitrates. In addition to this certain bacteria living in the nodules on the routes of leguminous plants e.g. pea, beans, etc; convert nitrogen into nitrogenous compounds which can be directly assimilated by the plant.

NITROGEN CYCLE • • • • •

Ther is a continoul turnover of nitrogen between the atmosphere, the soil, the sea and living organisms. The nitrogen passes from atmosphere to plants and animals, converted into useful products like ammonia,nitric acid etc. And still its percentage in the atmosphere remains practically unchanged This is due to the fact that combined nitrogen is constantly passing back to the atmosphere. This cycle of changes involved is known as nitrogen cycle.

•

USES OF NITROGEN COMPOUNDS • • •

Liquid ammonia is used as solvent Ammonia is used as a refrigerant in ice plants Ammonia is used in the manufacture of artificial silk,urea,manures,washing soda etc;

• • • • • • •

Nitrous oxide mixed with oxygen is used as anaesthetic for minor operations in dentidtry and surgery. Nitrous acid is used in the manufacture of azo-dyes. Nitric acid is used in the manufacture of fertilizers , explosives like TNT,GTN,etc. Nitric acid is used in the purification of gold and silver. Nitric acid is used in picking of stainless stell. Nitric acid is used in the manufacture of perfumes , artificial silk , medicine etc. Liquid nitrogen is used as a refrigerant.

Other uses: *Fertilizer Approximately 83% (as of 2003) of ammonia is used as fertilizers either as its salts or as solutions. Consuming more than 1% of all man-made power, the production of ammonia is a significant component of the world energy budget.

Precursor to nitrogenous compounds Ammonia is directly or indirectly the precursor to most nitrogen-containing compounds. Practically all synthetic and all inorganic nitrogen compounds are prepared from ammonia. An important derivative is nitric acid. This key material is generated via the Ostwald process by oxidisation of ammonia with air over a platinum catalyst at 700 - 850 °C, ~9 atm. Nitric oxide is an intermediate: NH3 + 2 O2 → HNO3 + H2O Nitric acid is used for the production of fertilizers, explosives, and natural organonitrogen other chemical compounds.

Minor and emerging uses Refrigeration - R717 Ammonia's thermodynamic properties made it one of the refrigerants commonly used prior to the discovery of dichlorodifluoromethane. Ammonia's toxicity complicates this application. Anhydrous ammonia is widely used in industrial refrigeration applications because of its high energy efficiency and low cost. Ammonia is used less frequently in commercial applications, such as in grocery store freezer cases and refrigerated displays due to its toxicity. For remediation of gaseous emissions Ammonia used to scrub SO2 from the burning of fossil fuels, the resulting product is converted to ammonium sulfate for use as fertilizer. Ammonia neutralizes the nitrogen oxides (NOx) pollutants emitted by diesel engines. This technology, called SCR (selective catalytic reduction), relies on a vanadia-based catalyst. As a fuel

Ammonia was used during World War II to power buses in Belgium, and in engine and solar energy applications prior to 1900. 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 its density approximately matches that for the oxidizer, liquid oxygen, which simplified the aircraft's design.

As a vehicle fuel Ammonia is proposed as a practical and clean alternative to fossil fuel for internal combustion engines. The biggest obstacle is the enormous increase in production required since present production, although the second most produced chemical, is a very small fraction of world petroleum usage. Ammonia has no more serious issues, as an alternative vehicle fuel compared to petrol or diesel, including toxicity, flammability, use in engines, pollution, energy density .It does require twice the storage volume of petrol/diesel. It can run in existing engines. It is already widely produced and distributed, and can be manufactured from renewable energy sources, coal or nuclear power. The main down side is that overall it is significantly less efficient than batteries. The 60 MW Rjukan dam in Telemark Norway, was producing ammonia via electrolysis of water for many years from 1913 producing fertilizer for much of Europe. Ammonia is already produced, transported and stored on a vast scale. In combination with coal gas it was used to run 20 buses on 8 routes covering many tens of thousands of miles with no injuries or engine damage.It can be used in existing engines with only minor modifications to carburetors / injectors. If produced from coal, the CO2 can be readily sequestrated. (the combustion products are nitrogen and water). In 1981 a Canadian company converted a 1981 Chevrolet Impala to operate using ammonia as fuel. The use of ammonia as fuel continues to be discussed. There are prototype solid state processes to use electricity to convert nitrogen and water directly to ammonia, which are claimed to be cheaper, more efficient and capable of much smaller scale application ie to otherwise stranded assets such as remote wind turbines. The calorific value of ammonia is 22.5 MJ/kg (9690 BTU/lb) which is about half that of diesel. In a normal engine, in which the water vapor is not condensed, the calorific value of ammonia will be about 21% less than this figure. Textile Liquid ammonia is used for treatment of cotton materials, give a properties like mercerisation using alkalies. And also used for pre-washing of wool. Poison treatment Solutions of ammonia in water can be applied on the skin to lessen the effects of acidic animal poisons, especially insect poison and jellyfish poison.