Group 15: Nitrogen – Ammonia
* Ammonia chloride, when heated with lime or caustic soda, evolves ammonia gas.
2NH4Cl + Ca(OH)2 + → Δ 2NH3 + 2H20 + CaCl2
* Ammonia chloride Slaked Lime Ammonia water calcium chloride
* In accordance with Le Chatelier’s principle, high pressure, high pressure and low temperature favours the better yield of ammonia.
* A high pressure of 200-300 atmospheres, an optimum temperature about 700k and the catalyst iron oxide along with promoter alumina are used to obtain better yields of ammonia.
Fe304,Al203
200-300 atm
N2 + 3H2 — 2NH3 ΔH = – 92.2 kJ mol-1
Nitrogen Hydrogen Ammonia
Nitrogen Hydrogen Ammonia
* On account of the presence of one lone pair in ammonia, the geometry of the molecule is trigonal pyramidal.
* An aqueous solution of ammonia precipitates hydroxides of metals from their aqueous salt solutions.
* An aqueous solution of ammonia combines with copper sulphate solution to form a deep blue copper tetrammine complex.
CuSO4 + 2NH4OH → Cu(OH)2 + (NH4)2SO4
Cu(OH)2 + (NH4)2SO4 + 2NH4OH → [Cu(NH3)4]SO4 + 4h2O
* Ammonia is used in the manufacture of certain industrially important chemicals such as nitric acid, baking soda and washing soda.
