Does hydrogen bonding explain the boiling points of NH3 and HF?
(b) Every hydrogen bond requires 1 lone pair on one molecule and a H bonded to N, O, or F on another. If we have N ammonia molecules, we have 3N H atoms and 1N lone pairs. So, even though an individual ammonia molecule can make four hydrogen bonds to other ammonia molecules, in a collection of ammonia N molecules at most N hydrogen bonds can form. For N HF molecules, there are 3N lone pairs and 1N H atoms, so at most N hydrogen bonds can form (even though an individual HF molecule can hydrogen bond to four other HF molecules). (c) HF and NH3 make fewer hydrogen bonds than H2O does, so H2O is expected to have a higher boiling point. 1.28: What kinds of hydrogen-bonded networks can you construct? This problem is part of the Expt 1 problem set. Be sure to do it in lab and check your answer. 1.30: What are the temperatures in an ice-water mixture? See PPT1.30 to view the experimental set up and results. Use Safari or Firefox if you can. There are often glitches in how things are displayed
