Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Shadow on January 15, 2013, 06:17:36 AM
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Why does the molar mass affect the boiling point?
I know its a common thing that "more massive" molecules have bigger boiling points, but how is this explained from the perspective of inter-molecular forces? I know how the London forces work, but I can't combine it with the molar mass :'(. Help would be appreciated!
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Hint: What makes the magnitude of London dispersion forces larger?
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That's what I was asking. I know the dipoles mechanism, but why and how does it change with the change of molar mass?
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Here is a simplification: If I gave you a big piece of velcro and a small piece of velcro, which would you expect to stick more strongly to a furry surface?
See also: http://en.wikipedia.org/wiki/London_dispersion_force
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The part with the surface area in understandable.
London forces become stronger as the atom or molecule in question becomes larger. This is due to the increased polarizability of molecules with larger, more dispersed electron clouds.
I heard about polarizability in ionic compounds, it makes them less polar. How does it affect molecules?