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

Question

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 (A)  5.47 text kJ text mol-1  (B)  text10 text.93 kJ text mol-1  (C)  text16 text.40 kJ text mol-1  (D)  text-16 text.4 kJ text mol-1

Tardigrade Admin · Accepted Answer

Total strength of all H-bonds =30.8-14.4 =16.4kJ mol-1 There are six nearest neighbours, but each hydrogen bond involves 2 molecules. Hence, effective neighbours = 3 Hence, strength of H-bond =(16.4/3)=5.47 kJ mol-1

$5.47 k J m o l^{- 1}$

$10 .93 k J m o l^{- 1}$

$16 .40 k J m o l^{- 1}$

$-16 .4 k J m o l^{- 1}$

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

Q. 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 30.8kJmol−1 and in the absence of H-bonding estimated ΔH of sublimation is 14.4kJmol−1 . Hence, strength of H-bond in solid NH3​ is

5.47kJmol−1

10.93 kJmol−1

16.40 kJmol−1

-16.4 kJmol−1

Total strength of all H-bonds =30.8−14.4 =16.4kJmol−1 There are six nearest neighbours, but each hydrogen bond involves 2 molecules. Hence, effective neighbours = 3 Hence, strength of H-bond =316.4​=5.47kJmol−1

$5.47 k J m o l^{- 1}$

$10 .93 k J m o l^{- 1}$

$16 .40 k J m o l^{- 1}$

$-16 .4 k J m o l^{- 1}$

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