Nitrogen Chemistry

How does nitrogen occur naturally

As a gas of diatomic molecules

Why is nitrogen so unreactive

Triple bonds very difficult to break

Why is ammonia soluble in water

It is polar and can form hydrogen bonds

Formula of ammonia

NH₃

What allows ammonia to form a dative covalent bond

Lone pair on the nitrogen

Ammonia’s ability to form dative covalent bonds allows it to act as what

• A ligand forming complex ions with transition metals

• A base accepting a proton to form ammonium ions

Formula of ammonium ion

NH₄⁺

Test for ammonia

• Gently heat with sodium hydroxide

• NH₄⁺_(aq) + OH^-_(aq) → NH_3(g) + H₂O_(l)

• Ammonia gas is alkaline so damp red litmus paper will turn blue if ammonia gas is produced

Names and description of NO

• Nitrogen monoxide, nitric oxide, nitrogen (II) oxide.

• A colourless gas

Name and description of N₂O

• Dinitrogen monoxide, nitrous oxide, nitrogen (I) oxide (laughing gas)

• Colourless, sweet smelling gas

Name and description of NO₂

• Nitrogen dioxide, nitrogen (IV) oxide

• Brown, toxic gas with a sharp odour

Formula of nitrate (V) ions

NO₃^-

Test for nitrate (V) ions

• Heat with sodium hydroxide and aluminium foil / devarda’a alloy

• Aluminium reduces nitrate ions to ammonia

  • 3NO_3(aq) + 8Al_(s) + 5OH^-_(aq) + 18H₂O_(l) → 3NH_3(g) + 8[Al(OH)₄]^-_(aq)

• Ammonia gas is alkaline so damp red litmus paper will turn blue if ammonia gas is produced

Conversion of nitrogen to ammonia

N₂ + 3H₂ → 2NH₃

Conversion of ammonia to ammonium ions

NH₃ + H⁺ → NH₄⁺

Conversion of ammonium ions to nitrate (III) ions

NH₄⁺ + O₂ → NO₂^- + 4H⁺ + 2e^-

Conversion of nitrate (III) ions to nitrate (V) ions

NO₂^- + H₂O → NO₃^- + 2H⁺ + 2e^-

Conversion of nitrate (V) ions to nitrogen

2NO₃^- + 12H⁺ + 10e^- → N₂ + 6H₂O

Production of nitrogen oxides from nitrogen

• N₂ + O₂ → 2NO

• N₂ + 2O₂ → 2NO₂

• 2N₂ + O₂ → 2N₂O