1. Tardigrade
  2. Question
  3. Chemistry
  4. Each NH3 molecule has six other NH3 molecules as nearest neighbours in solid state; AH of sublimation of NH3 molecule at the m. p is 30.8 text kJ text mol-1 and in the absence of H-bonding estimated Δ H of sublimation is 14.4 text kJ text mol-1 . Hence, strength of H-bond in solid NH3 is

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Q. Each $ N{{H}_{3}} $ molecule has six other $ N{{H}_{3}} $ molecules as nearest neighbours in solid state; AH of sublimation of $ N{{H}_{3}} $ molecule at the m. p is $ 30.8\text{ }kJ\text{ }mo{{l}^{-1}} $ and in the absence of H-bonding estimated $ \Delta H $ of sublimation is $ 14.4\text{ }kJ\text{ }mo{{l}^{-1}} $ . Hence, strength of H-bond in solid $ N{{H}_{3}} $ is

MGIMS WardhaMGIMS Wardha 2013

Solution:

Total strength of all H-bonds $ =30.8-14.4 $ $ =16.4kJ\,mo{{l}^{-1}} $ There are six nearest neighbours, but each hydrogen bond involves 2 molecules. Hence, effective neighbours = 3 Hence, strength of H-bond $ =\frac{16.4}{3}=5.47\,kJ\,mo{{l}^{-1}} $