1. For which pair of molecules is London Dispersion strongest?
QUESTION:
For which pair of molecules is London Dispersion strongest?
A. H2O and H2O B. H2O and H2S
C. H2S and H2S
London dispersion forces are stronger the larger the molecules.
H2S is larger than H2O. O and S both belong to group VIA. S is larger than O.
Overall, intermolecular forces are stronger among H2O molecules because they are capable of extensive hydrogen bonding interaction. Evidence: under ordinary conditions, H2O is a liquid, H2S is a gas
For which pair of molecules is London Dispersion strongest?
A. H2O and H2O B. H2O and H2S
C. H2S and H2S
PAUSE CLICK
London dispersion forces are stronger the larger the molecules.
H2S is larger than H2O. O and S both belong to group VIA. S is larger than O.
Therefore, among the choices given,
London dispersion forces would be strongest between two H2S molecules.
THe correct answer is C.
Note that, overall, intermolecular forces are actually stronger among H2O molecules
because they are capable of extensive hydrogen bonding interaction.
One evidence of this is that under ordinary conditions, H2O is a liquid while H2S is a gas.
You will recall that molecules have more freedom of movement in the gas phase.
Strong intermolecular forces would cause molecules to stay closer together as in a liquid.
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2. as illustrated here for the water molecule show in the middle.
Extensive hydrogen bonding interactions among water molecules explains anomalously high boiling point of water. Substances made of molecules as small as (comparable in size to) water molecules are gases under ordinary conditions (ex. O2, N2).
Extensive hydrogen bonding interactions among water molecules is responsible for the anomalously high
boiling point of water. Substances made of molecules that are comparable in size to water molecules are gases
under ordinary conditions. The figure here shows illustrates how extensive hydrogen bonding can be
among water molecules. Each water molecule is capable of up to four hydrogen bonding interactions
as illustrated here for the water molecule show in the middle.
HIGHLIGHT water molecule in middle
...here’s one
CLICK and another
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and another
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3. Video ID: © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08