In solid NH 3 , each NH 3 molecule has six other NH 3 molecules as nearest neighbours. The enthalpy of sublimation of NH 3 (s) at its melting point is 33.4 kJ/mol and estimated value of enthalpy of su

Question

In solid NH 3 , each NH 3 molecule has six other NH 3 molecules as nearest neighbours. The enthalpy of sublimation of NH 3 (s) at its melting point is 33.4 kJ/mol and estimated value of enthalpy of sublimation of NH 3 (s), where there were no hydrogen bonds, is 15.4 kJ/mol. What is the average strength of hydrogen bonds in solid NH 3 in kJ/mol?

TestHub · Accepted Answer

Hydrogen bonding contributes 33.4 - 15.4 = 18 kJ/mol. Each molecule has 6 neighbours but every H-bond is shared by 2 molecules, so bonds per molecule = 6/2 = 3. Average strength = 18/3 = 6 kJ/mol. Answer: 6.

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