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Author Topic: Does odor have weight?  (Read 3036 times)

Offline Karen W.

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Does odor have weight?
« on: 10/11/2009 12:18:57 »
You know we often say that the aroma
or scent of a womens perfume just hangs
in the air like fog, but does it have any weight?


 

Offline Nizzle

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Does odor have weight?
« Reply #1 on: 10/11/2009 14:46:45 »
the molecules will have a weight yes.
 

Offline latebind

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Does odor have weight?
« Reply #2 on: 10/11/2009 15:24:55 »
If body odour has a weight, then I'm sure some people on the tubes in London weigh a ton. :)
 

Offline Bored chemist

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Does odor have weight?
« Reply #3 on: 10/11/2009 18:37:22 »
"Now comes the question of how simple gas molecules can suspend large, heavy molecules such as t-butyl mercaptan (C4H9SH) or ethanethiol (CH3CH2SH) added to natural gas to allow detection of leaks. 
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Why would they need "suspending"? These molecules are fairly volatile anyway.
If you think that the molecules of, for example, methane, are holding up the mercaptans, what do you think is holding the methane up?
I might get round to editing that wiki page- it's misleading.
 

Offline Bored chemist

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Does odor have weight?
« Reply #4 on: 10/11/2009 21:59:54 »
All molecules are volatile; it's just a matter of how volatile.
 

Offline Bored chemist

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Does odor have weight?
« Reply #5 on: 11/11/2009 18:15:04 »
When you were at school did they tell you about the properties of solids, liquids and gases?

Gases fill the container that they are in.
It may take a while but they eventually diffuse throughout the volume (technically they are slightly more concentrated at the bottom of the container but the effect is not worth worrying about for any practical sized container).
 

Offline Bored chemist

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Does odor have weight?
« Reply #6 on: 12/11/2009 18:32:21 »
Brownian motion is the movement of things that are much bigger than the molecules round them that occurs because sometimes more mokecules hit the particles on one side than on the other.

Air could be separated by centrigugation but it wolud be rather inefficient.

Nitrogen generators run on membranes that are permeable to O2 but not N2 or on pressure swing absorbtion.
 

Offline rosy

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Does odor have weight?
« Reply #7 on: 12/11/2009 22:46:57 »
You can work out the extent to which heavier and lighter gases would be differently distributed in an atmosphere at equilibrium (with no convection or anything stirring it up). It featured in my (first year, I think) chemistry (or maybe physics, probably physics) undergrad course. As far as I recall you wouldn't expect to see much separation because although it would be a slightly lower energy system if all the gases were stratified by molecular weight, the entropy (tendency for jumbled-up situations to be the most likely ones) wins out and there's not a lot of difference in gas composition with height (tho' I think we do tend to lose helium to space as a result of it being so light). However, in order to remember enough to explain it I'd have to look it up and re-learn it, which I haven't time for at present...
 

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Does odor have weight?
« Reply #7 on: 12/11/2009 22:46:57 »

 

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