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Author Topic: polarity and insolubility  (Read 18853 times)

Offline MayoFlyFarmer

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Re: polarity and insolubility
« Reply #25 on: 21/04/2004 17:09:48 »
Sorry, it was really late after a long day when I posted that.....  I was putting the Cl in as the central atom.  Even I should know not to do that!

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Offline Ylide

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Re: polarity and insolubility
« Reply #26 on: 22/04/2004 04:15:27 »
Nilmot,

Yes, contrary to what my girlfriend tells me, size is important.  [:0]

Smaller molecules are generally more soluble than larger ones.  When you put things into solution, they molecules of the solvent must completely surround and isolate the solute from other solute particles.  Obviously, the larger the solute molecule, the more water it takes to solvate it and the less water is available to surround a different one.  





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Offline nilmot

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Re: polarity and insolubility
« Reply #27 on: 22/04/2004 10:54:22 »
The non-related bit: Sometimes size doesn't really matter is she likes you :D

Is it the same for organic molecule? Let's say lipid, it's a relatively large molecule (obvious there are larger ones). But using an organic solvent it seems to be dissolved quite quickly.

Tom
 

Offline Ylide

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Re: polarity and insolubility
« Reply #28 on: 24/04/2004 03:11:59 »
I was referring to aqueous solutions in reference to size, sorry, should have specified.  Size is a major factor when the mechanism of solvation is hydrogen bonding or dipole attractions.  Large organic molecules are going to be attracted due to dispersion forces which actually become stronger as the molecule size increases.  I should have been more clear there.

Another general property is that the bigger the organic molecule, the less of an effect polarity and hydrogen bonding will have on solution properties.  For example, smaller organic acids (i.e. acetic, benzoic) are soluble in water but once the carbon structure starts getting big, it's no longer soluble in neutral water.  (i.e. decanoic acid)  It will, however, be soluble in an aqueous solution of high pH, as the removal of the acidic hydrogen(s) creates a true ion (rather than a mere hydrogen bonding oxygen) that is strongly attracted to a polar solvent like water.  


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Offline nilmot

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Re: polarity and insolubility
« Reply #29 on: 24/04/2004 10:41:13 »
Thank's cannabinoid.

Tom
 

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Re: polarity and insolubility
« Reply #29 on: 24/04/2004 10:41:13 »

 

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