Nitrogen

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Overview

Nitrogen is an inert gas which constitutes about 78% by volume of the atmosphere. Nitrogen gas is prepared in the laboratory by heating the mixture of ammonium chloride and sodium nitrite in the ratio of 1:1. This note provides us the information about nitrogen and its preparation.
Nitrogen

Symbol: N
Molecular formula: N2
Valency: 3
Position in periodic table: Group-V A, Period-2nd
Electronic configuration: 2, 5 (1S2, 2S2 2P3)
Atomic number: 7
Atomic weight: 14
Molecular weight: 28 amu
Freezing point:- 210 °C
Boiling point: -196 °C

Occurrence

Nitrogen is found in both free and combined states. It occupies 78.07% by volume.

General methods of preparation of nitrogen gas

By heating copper in air:

Firstly, air is passed through lime water and then concentrated sulphuric acid to make the air free from carbon dioxide and moistures respectively. The air contains only nitrogen and oxygen which are passed over the heated copper wire as shown in the figure. Here copper combines with oxygen to make copper oxide and nitrogen gas passes over. This nitrogen can be collected by downward displacement of water.

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By burning phosphorous in air:

Nitrogen gas can be prepared by burning phosphorous in air. A crucible with phosphorous is taken and allowed to float on water. Then phosphorous is burnt in crucible is covered with gas jar as shown in figure. The oxygen of the gas jar is consumed during the burning of phosphorous penta oxide is formed. The gas left in the jar is nitrogen.
4P + 5O2 → 2P2O5

By decomposition of compounds containing nitrogen

Like, when dilute solution of ammonium nitrite is heated, nitrogen gas is produced.
NH4NO2→ N2 +2H2O

Laboratory preparation of nitrogen gas

Principle:
When the solution of sodium nitrite and ammonium chloride is heated they react together and liberate nitrogen gas.
NaNO2 + NH4Cl → NaCl + H2O +N2

Take a mixture of ammonium Chloride and Sodium nitrate in equivalent amount in a round bottom flask. Some water is added to make the solution of the mixture. Then the delivery tube is fitted with a round bottom flask with the help of a cork. The flask is heated gently with a source of heat. After that gas is produced by the reaction of chemicals and is collected in gas jar by downward displacement of water.

Precautions

  • Ammonium chloride and sodium nitrite should not be used in solid form because ammonium chloride, being a sublimate, sublimes and escape in form of vapour on heating.
  • Apparatus should be made airtight.
  • Ammonium chloride and sodium nitrite should be taken in equivalent amount.

Test of nitrogen

When burning magnesium ribbon is inserted in a jar containing gas, if it burns continuously and forms magnesium nitride, it proves that gas is nitrogen.

Properties of nitrogen

Physical properties
  • It is neutral to the indicator.
  • It is non-combustible gas but it is combustion supporter.
  • It liquefies at -196°C and solidifies at -210°C.
  • Nitrogen gas in generally inert, nonmetallic, colourless, odorless and tasteless.
  • The atomic number of nitrogen is 7 and its atomic weight is 14.0067.
  • The density of nitrogen at 0oC is 1.251 grams/liter and its specific gravity is 0.96737.
  • Nitrogen forms trivalent bonds in most compounds.
Chemical properties
  • When a mixture of nitrogen and hydrogen is heated to about 500°C, at the atmospheric pressure of 200-900 atmosphere and in the presence of a catalyst finely divided iron and molybdenum, ammonia gas is liberated.
    N2 + 3H2 → 2NH3
  • When a mixture of nitrogen of nitrogen and oxygen is heated at 2000°C- 3000°C in electric arc, they combine together and give oxides of nitrogen.
    2N2 + O2 → 2N2O (Nitrous oxide)
    N2 + O2 → 2NO (Nitric oxide)
    N2 + 2 O2 → 2NO2 (Nitrogen dioxide)
  • Reactive metals like magnesium, calcium, aluminium etc. when burnt in nitrogen forms respective nitrides.
    3Mg + N2 → Mg3N2 (magnesium nitride)
    heat
    3Ca + N2 → Ca3N2 (calcium nitride)
    heat
    2Al + N2 → 2AIN (aluminium nitride)
    heat

Uses of nitrogen

  • It is used to manufacture explosive.
  • It is used for replacing fuel in fuel tanks in airplane.
  • It is used in filling electric bulbs

Things to remember
  • Nitrogen is an inert gas which constitutes about 78% by volume of the atmosphere.
  • Nitrogen gas is prepared in the laboratory by heating the mixture of ammonium chloride and sodium nitrite in the ratio of 1:1.
  • Nitrogen combines with hydrogen in 1:3 ratio to form ammonia gas.
  • Nitrogen is neither combustible nor a supporter of combustion.
  • Nitrogen gas is used to manufacture explosive.
  • It includes every relationship which established among the people.
  • There can be more than one community in a society. Community smaller than society.
  • It is a network of social relationships which cannot see or touched.
  • common interests and common objectives are not necessary for society.
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Questions and Answers
Nitrogen is the seventh element on the periodic table. It is located in period 2 and group 15.

Physical properties on nitrogen are:

1.Nitrogen is a colorless, odourless and tasteless.
2. It is slightly lighter than air.
3. It is very slightly soluble in water. etc.
Nitrogen is an inert gas which constitutes about 78% by the volume of the atmosphere.

We use nitrogen gas for:

1. manufacturing nitric acid.
2. Manufacturing of nitrogen rich fertilizer.
3. Nitrogen gas is used to manufacture explosive.

Nitrogen gas is prepare in the laboratory by heating the mixture of amoniumchloride and sodium nitrite in the ratio 1:1. NH4CI + NaNO2 --------> NaCI + N2 + 2H2O

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