luni, 8 aprilie 2013

NITROGEN - CHEMICAL ELEMENTS

                                                        
                                        NITROGEN

Chemical symbol: N

Atomic mass: 14
Mass number "Z": 7

Nitrogen is found in the fifth main group of the first period in the periodic table.

PHYSICAL:        

             Nitrogen is a colorless, odorless, tasteless and non-toxic. It can be condensed into a colorless and then compressed into a colorless crystalline solid.Denistatea nitrogen is slightly less than air and is less soluble in water than oxygen. He did not support life beings that we breathe.The melting temperature of nitrogen is - 210, 01 ° C, while the boiling point is - 195, 79 ° C.Natural state:

        
Nitrogen gas is one of the most widespread in nature. It is found both in the free state and complexed form:In the free state, nitrogen is 78% of atmospheric air.Nitrogen compounds are:-Inorganic (ammonia, nitrates, etc.).-Organic (urea, proteins)Nitrogen found in a proportion of 1 to 10% each in living organisms.

CHEMICAL PROPERTIES:

         
Nitrogen does not burn and does not support combustion. It presents a relatively low chemical reactivity.Reaction with oxygen:At temperatures above 3000 ° C, nitrogen combines with oxygen to form nitrogen monoxide:N2 + O2 (2NO (the reaction is reversible)Reaction with hydrogen:Temperature and high pressure in the presence of a catalyst, nitrogen reacts with hydrogen, resulting ammonia:N2 + 3H2 (2NH3 (the reaction is reversible)The main inorganic nitrogen compounds are:NH3HNO3NH4Cl (ammonium salts)(NH4) 2CO3 (baking powder)

NITROGEN CYCLE IN NATURE:

Reduced activity of nitrogen allowed the use of an inert atmosphere increases. He is protectorfata element of energy and unwanted actions of oxygen.Higher plants and animals can not directly absorb nitrogen from the air. Plants derive nitrogen they need through their roots from the soil, which contains ammonia or ammonium ions and nitrates. Combinations of plant nitrogen are transferred grazing animals, along with their food.
          
Combined nitrogen in the body of animals and plants in soil is reantoarce after their death and decay during decay occurring bacteria turn nitrogen proteins and other organic combinations ammonia.The land cultivated by man, assimilable nitrogen extracted from plants is greater than that which regenerate naturally. For this reason we need to add these soil nitrogen fertilizers.

UTILITY OF NITROGEN:
        

      Most nitrogen used in industry is distilled from liquid air. This is then used to synthesize ammonia. Of ammonia produced in this way is get a wide variety of chemicals, including fertilizers, chemical fertilizers, etc..Another is the use of nitrogen in combination with oxygen, achieving an anesthetic used in medicine during surgery.A more recent application is the use of nitrogen in the field of cryogenics.Nitrogen is also used in ink industry

.HOW WAS DISCOVERED:

Even long after, when alchemist Helmont introduces the notion of gas, all gas is called, air "with the addition that mark one of its properties. Mentions Van Helmont but also one of the components as the air, gas, Scots ". It was carbon dioxide, and the name seems to come from imposbiliatea of ​​condensation. Chemical study of the air starts to become a concern of researchers only in the second half of the eighteenth century. The first scientist who finds that air is not composed of one kind of substance is Joseph Black, an English chemist of French origin. Nitrogen occurs later, but not as distinct body, but confused with carbon dioxide. But since the discovery and nitrogen is decoperitorului name is Daniel Rutherford. Who descpoerise nitrogen was a young 23 year old Scotsman who made his thesis dissertation at the University of Edingburg to Professor John Black. Young chimst do research on air, but about plant respiration. In the course of numerous experiments have to prove that the air "intertinea not burning is not only carbon dioxide, but nitrogen, which have many physical similarities. Thus passing air over charcoal D. Rutherford reddened (charcoal) and combustion product washing with caustic alkalis and lime water, which is retained carbon dioxide (passing the respective carbonates).,, Air "which went on after the washing was Rutherford nitrogen that identifies it as a new body and called him, air metific "because intertine life, considering it a kind of,, flawed" as the result by respiratie.Astfel Rutherford is recognized as the discoverer of nitrogen. Five years later (AL Lavoisier showed that nitrogen exists in the free state in the atmosphere and that he reperzinta 79% of volume of air. In 1789, when editing the first chemical nomenclature, A.Lavoisier (with Guyton of glanders) replaces the name of,, mephitic air "and the,, air flogisticat" with the nitrogen from the binding of two Greek words (a = privative and zoe = life) so lifeless because no animal life which it intertinea inspire. During 1823, JA Chaptal (1756-1832), another French chemist, so nitrogen named nitrogen (after the Greek words Natron = saltpeter and gennao = to produce), so producer of nitrate (saltpeter). nitrogen Name remained prevalent especially in France, and the nitrogen was over in English-speaking countries.

                 NATURALLY and METHODS of OBTAINING :                                        


Nitrogen.

 
It is widespread in nature besides that found in Earth's crust in the amount of 3x10-2%, it is also a main component of air, which, as is known, consists of 78% (by volume) nitrogen free. Most of the nitrogen in the earth's crust is in the form of organic combinations, while combinations of inorganic nitrogen (except nitrate NaNO3) not found in large quantities in nature. Industrial methods of obtaining nitrogen is based on the separation of nitrogen air by evaporating liquid oxygen in special instaltii. In laboratory conditions very pure nitrogen is obtained from combinations of, for example, by passing a current of ammonia over copper oxide reddened or break down ammonium nitrite NH4NO2 hot. Physical properties under normal conditions of temperature and Persia, nitrogen is a colorless, odorless and tasteless, a liter of nitrogen cantaerste 1.2506 g high Persia The strong cooling, nitrogen passes first a colorless liquid with a point -195.8 Boiling OC and then a solid which crystallizes in the cubic system and melts at -210.1 OC. Density of liquid nitrogen is 0.88 g/cm2. Nitrogen gas has a lower thermal conductivity than the liquid. Chemical properties at low setpoints nitrogen is less active, in terms of developing alloys nitrogen is an element that combines with metals and metalloids energrtic. More important are hydrogenated combinations of nitrogen, primarily amonacul because by its action on certain metals or their oxides, nitrides form combinations that are obtained are stable at high temperatures and hot. Nitrogen and hydrogen. When passing an electrical discharge through a mixture of hydrogen and nitrogen to ammonia: N2 3 H 2U2NH3, because this reaction is exothermic and is accompanied by the usual temperature of a release of 11.89 kcal / mol NH3 course by increasing the temperature will decrease the concentration of ammonia.

                    Nitrogen and phosphorus.
 
Phosphorus not combine the usual temperature, do not combine or by heating at 300oC in nitrogen, phosphorus and ammonia. Phosphorus rivets - PN - form the passage of electric sparks through the vapor of phosphorus and nitrogen. Metal rivets. Combinations of metals with nitrogen is nitrogen or ammonia formeazaprin action. Lithium, magnesium, boron and aluminum, the type that reacts with oxygen in the air combines with nitrogen. Lithium, calcium, strontium, barium, magnesium, boron, aluminum, rare earths, silicon, titanium, zirconium, Cerium, thorium, manganese combine directly with nitrogen by heating. On heating in Ammon formed rivets: potassium, copper, barium, magnesium, zinc, aluminum, titanium, manganese, iron.

          
               NITROGEN USE:

              Nitrogen is used in filling pure electric lamps. Combinations of nitrogen, the technique used is ammonia (NH3) which is used in cold indusria to obtain artificial ice in the manufacture of nitric acid and synthetic nitrogen fertilizer. Technique is of great importance nitric acid (HNO3), widely used in chemical industry. It is also used in the manufacture of dyes, drugs, explosives getting.Nitrogen was captured for the first time in 1772 by British-born Dr Daniel Rutherford and officially recognized as one of the elementary gases around the year 1776 by the French chemist Antoine Laurent Lavoisier