InterviewSolution
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InterviewSolution
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In solid ammonia, each `NH_(3)` molecule has six other `NH_(3)` molecules as nearest neighbours. `DeltaH` sublimation of `NH_(3)` at the melting point is `30.8 k J mol^(-1)`, and the estimated `DeltaH` sublimation in the absence of hydrogen bonding is `14.4 kJ mol^(-1)`. the strength of a hydrogen bond is `NH_(3)` isA. `5.47 kJ " mol"^(-1)`B. `10.93 kJ " mol"^(-1)`C. `16.40 kJ " mol"^(-1)`D. `-16.4 kJ " mol"^(-1)` |
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Answer» Correct Answer - A Total strength of all H-bonds `=30.8-14.4=16.4` kJ `mol^(-1)` There are six nearest neighbours but each H-bond involves two molecules. Hence the effective neighbours `=3` `:.` Strength of H-bond `=(16.4)/3` `=5.47 kJ "mol"^(-1)` |
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