NITROGEN AND ITS COMPOUNDS

• What is the atomic number of Nitrogen?


  7
• Nitrogen exists as?


  A diatomic molecule
• Nitrogen belongs to which group and period in the periodic table respectively?

  V and 2
• During laboratory isolation of Nitrogen, why is concentrated NaOH used?


  To absorb carbon(IV)oxide
• What is the equation of the reaction that takes place in the flask?

  2NaOH(aq)+CO₂(g)=Na₂CO₃(aq)+H₂O(l)
• During laboratory isolation of Nitrogen from air, why is the air first passed through a filter?

  To remove dust and any other suspended particles
• Where is water removed in the fractional distillation chamber?


  At the condensation chamber where it is cooled to -25°C
• At what temperature is Nitrogen obtained?


  -196°C
• Which gas is distilled off first ?Explain


  Nitrogen. This is because it has a lower boiling point
• Which other gases are obtained from this process?

  Argon and Oxygen
• How is Nitrogen prepared in the laboratory?

  By heating ammonium nitrite
• Write the equation of the reaction


  NH₄NO₂(s)=N₂+2H₂O(l)
• Nitrogen is a non metal in group V of the periodic table. It has an atomic number of seven and has an electron arrangement of 2.5. Nitrogen exists in air as a gaseous element consisting of diatomic molecules. About 78% by volume of the atmosphere is composed of nitrogen making it the most important source of nitrogen.
• Nitrogen also occurs combined in Compounds such as sodium nitrate, potassium nitrate and proteins
• Isolation of Nitrogen from Air

  1. Pass air through concentrated potassium hydroxide or sodium hydroxide to absorb carbon(IV) oxide

  2. Pass remaining air over heated copper turnings to remove oxygen

  3. Collect residual gas as nitrogen
• Fractional distillation of liquefied air


  1. Remove dust particles through electrostatic precipitation

  2. Pass air through concentrated sodium hydroxide solution to remove carbon(IV) oxide

  3. Cool air to -25°C to separate water vapour

  4. Compress air to 200 atm and cool to -200°C

  5. Fractionally distil liquid air to separate nitrogen and oxygen
• Laboratory preparation of nitrogen


  1. Heat a mixture of ammonium chloride and sodium nitrite

  2. Ammonium nitrite forms and decomposes to nitrogen and steam
• Nitrogen


  • Colourless, odourless, tasteless gas slightly less dense than air
  • Boiling point -196°C
  • Slightly soluble in water
  • Neither burns nor supports combustion
  • Chemically unreactive under ordinary conditions
• Laboratory preparation of nitrogen(I) oxide

  1. Heat ammonium nitrate

  2. Ammonium nitrate decomposes to form nitrogen(I) oxide and steam
• Nitrogen(I) oxide


  • Colourless gas with pleasant smell
  • Causes insensitivity when inhaled
  • Slightly less dense than air
  • Fairly soluble in cold water but insoluble in warm water
• Laboratory preparation of nitrogen(II) oxide


  1. Reaction of copper and dilute nitric(V) acid

  2. Nitrogen(II) oxide is oxidised by oxygen to form nitrogen(IV) oxide
• Nitrogen(II) oxide


  • Colourless gas
  • Slightly soluble in water
  • Neither burns nor supports combustion
  • Oxidises some strongly heated elements to their oxides
• Preparation of nitrogen(IV) oxide

  1. Reaction of concentrated nitric(V) acid on copper turnings

  2. Thermal decomposition of lead(II) nitrate
• Nitrogen(IV) oxide


  • Easily liquefied gas
  • Exists as an equilibrium mixture of itself and dinitrogen tetraoxide at room temperature
  • Dissociates to form a colourless mixture of nitrogen(II) oxide and oxygen when heated
• Lead(II) nitrate


  The most suitable because it is not hydrated
• Decomposition of lead(II) nitrate


  Heated to form lead(II) oxide, nitrogen(IV) oxide and oxygen
• The set up below can be used to prepare nitrogen(IV) oxide from metal nitrates
• Preparation of nitrogen(IV) oxide


  1. Lead(II) nitrate heated

  2. Oxygen gas

  3. Dinitrogen tetraoxide formed by cooling nitrogen(IV) oxide in ice-cold water

  4. Oxygen gas collected over water
• Nitrogen(IV) oxide


  • Easily liquefied
  • Exists as an equilibrium mixture of itself and dinitrogen tetraoxide at room temperature
• Dissociation of nitrogen(IV) oxide


  Heated to form nitrogen(II) oxide and oxygen
• Nitrogen(IV) oxide


  Reddish-brown gas with an irritating pungent smell, poisonous, denser than air
• Dissolution of nitrogen(IV) oxide in water

  Forms nitric(III) acid and nitric(V) acid
• Reaction of nitrogen(IV) oxide with alkalis


  Forms a mixture of their corresponding nitrates and nitrites
• Reaction of magnesium with nitrogen(IV) oxide

  Forms magnesium oxide and nitrogen
• Reaction of phosphorus with nitrogen(IV) oxide

  Forms phosphorus(V) oxide and nitrogen
• Uses of nitrogen(IV) oxide

  • In the manufacture of nitric(V) acid
  • As an intermediate in the manufacture of explosives, nylon and plastics
  • As an oxidising agent in the lead chamber during the manufacture of sulphuric(VI) acid
• Ammonia


  Compound of nitrogen and hydrogen, gas at room temperature
• Laboratory preparation of ammonia


  1. Heating a mixture of an ammonium salt and an alkali

  2. Calcium oxide used as a drying agent
• Concentrated sulphuric(VI) acid reacts with ammonia to form ammonium sulphate
• Calcium chloride forms a complex compound with ammonia