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 30.4 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 30.4 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

The contribution of hydrogen bonding is calculated as 30.4 - 15.4 = 15 kJ/mol. Each molecule has 6 neighbors, but each hydrogen bond is shared by two molecules. Therefore, the number of hydrogen bonds per molecule is 6/2 = 3.

The average strength of each hydrogen bond is 15/3 = 5 kJ/mol.

Answer: 5 kJ/mol.

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