 |
Discovery |
| |
Daniel Rutherford, a Scottish Physician, discovered nitrogen in 1772. But it was Lavoisier, who proved that nitrogen is an element and that it was not a supporter of combustion and respiration. He called it 'azote' meaning 'no life'. The name 'Nitrogen' was given to it by Jean Antoine Chaptal (1756 - 1832), in the year 1790. |
|
Occurrence |
| |
Nitrogen exists in the free and in the combined form in the atmosphere of the earth. In the free state it occupies about 80% by volume of air. In the combined form, it is present as ammonia and all ammonium compounds, in nitric acid and in all nitrates, nitrites and in all living things in the form of proteins. |
|
Preparation of Nitrogen from Air |
| |
The chief source of free nitrogen is atmospheric air and nitrogen is usually prepared from it. Air free from dust, water vapour and carbon dioxide is compressed in a compression chamber for liquefaction. Firstly, the pressure on the air is increased to about 200 atmospheres. It is then released through a spiral into a low-pressure area, where intense cooling of the air takes place. |
|
Preparation of Nitrogen From Chemical Compounds |
| |
* By treating excess ammonia with chlorine, ammonium chloride and nitrogen are formed.
 |
|
Laboratory Preparation of Nitrogen |
| |
In the laboratory, nitrogen is prepared by heating a mixture of ammonium chloride and sodium nitrite and a small quantity of water. If ammonium nitrite is heated by itself it decomposes to produce nitrogen gas. However, this reaction is very fast and may prove to be explosive.
 |
|
Physical Properties of Nitrogen |
| |
(i) Color: Nitrogen is a colorless gas.
(ii) Odor: It has no odor.
(iii) Taste: It is a tasteless gas. |
|
Chemical Properties of Nitrogen |
| |
Combination with elements
Nitrogen does not easily combine with other elements under ordinary conditions. A molecule of nitrogen is diatomic. These two atoms have combined by mutually sharing three pairs of electrons. |
|
Physiological Action |
| |
Nitrogen is non-poisonous. But animals placed in an atmosphere of nitrogen die due to asphyxiation (lack of oxygen). |
|
Tests for Nitrogen |
| |
Nitrogen is a colorless, odorless, tasteless, neutral gas, which neither burns nor supports combustion. |
|
Uses of Nitrogen |
| |
Nitrogen is used in high temperature thermometers where mercury cannot be used. This is because mercury boils at 356.7oC and hence cannot be used in such thermometers. A volume of nitrogen is enclosed in a vessel and introduced into the region of high temperature. Depending upon the temperature, expansion of the nitrogen volume takes place. Then applying the gas equation, the temperature is calculated. |
|
Nitrogen Cycle |
| |
Nitrogen is an essential constituent of animal and plant matter as it forms proteins, which are the building blocks of life. The ultimate source of nitrogen is atmospheric nitrogen but neither plants nor animals are capable of assimilating free nitrogen. |
|
Summary |
| |
Nitrogen has 5 electrons in its valence shell. It has a valency of 3 with respect to hydrogen and a valency upto 5 with respect to oxygen. |
