HardChemistryHigh School (11–12)Chemical Bonding › Molecular Orbitals and Hydrogen BondsNumericalBoard ExamAPA-LevelIB
Hydrogen sulphide, hydrogen selenide and hydrogen telluride boil at 213 K, 232 K and 271 K; their…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Hydrogen sulphide, hydrogen selenide and hydrogen telluride boil at , and ; their heavier atoms are in periods 3, 4 and 5. Fit a straight line to these three points and extend it to period 2. What boiling point does it predict for water, and how far above it does real water, at , boil?
Need a reminder? The key ideaShow
A hydrogen bond is the attraction between a hydrogen atom joined to fluorine, oxygen or nitrogen and a lone pair on another such atom. Intermolecular hydrogen bonds join molecules and raise boiling points; intramolecular ones form within one molecule. Water boils at , far above , and .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The slope. per period.
Step 2. The mean point. at period .
Step 3. Extend to period 2. .
Step 4. Compare. .
Answer: the trend predicts about ; real water boils about higher, thanks to hydrogen bonds.
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