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Topic: Polar and non-polar molecules  (Read 11268 times)

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mrg09

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Polar and non-polar molecules
« on: March 29, 2006, 04:32:01 PM »
An ionic compound is more soluble in a polar molecule such as water. A covalent compound is more soluble in a non-polar molecule like 2-propanol. If i've got that right, can anyone explain why this is? Thanks  :)
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Offline Mitch

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Re:Polar and non-polar molecules
« Reply #1 on: March 29, 2006, 09:00:11 PM »
I seriously doubt all covalent molecules are more soluble in isopropanol than water. But, since this is a high school question it may be a "true" statement.
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Offline tamim83

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Re:Polar and non-polar molecules
« Reply #2 on: March 30, 2006, 12:45:30 PM »
Ionic compound are definitely more solubile in polar solvents like water.  This is true because since polar molecules like water have a paositive and negative end and this helps to pull ionic compounds apart. This process is called solvatioon.  

The second part of your statement can be made true.  It is more accurate to say that nonpolar molecules will dissolve in nonpolar molecules and polar molecules will dissolve in ploar molecules.  So isoprpinol (which I think is slightly polar, I am pretty sure about tthis but I don't want to go against your teacher or anything) will dissolve in water (which is also polar).  Benzine is non polar and will dissolve in vegetable oil which is also nonpolar.  The simple reason is that we have this wonderful rule in chemistry called "like dissolves like" ;), two things that are alike will dissolve in one another.  

Hope this helps, Cheers :)
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Moonshyne

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Re:Polar and non-polar molecules
« Reply #3 on: March 31, 2006, 02:01:41 AM »
Quote from: MRG on March 29, 2006, 04:32:01 PM
An ionic compound is more soluble in a polar molecule such as water.

Some ionic compounds are not soluble in water at all (most ionic solids containing Ag, Pb, or Hg, with exception to NO3 anion). If the ionic compound is considered soluble, then yes it would be more soluble in a polar solvent such as water.
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Offline tamim83

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Re:Polar and non-polar molecules
« Reply #4 on: March 31, 2006, 12:36:16 PM »
I comepletely forgot about the solubility rules :o I should know better.  
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mrg09

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Re:Polar and non-polar molecules
« Reply #5 on: March 31, 2006, 03:23:00 PM »
Thanks for the help guys  ;)
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hay

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Re:Polar and non-polar molecules
« Reply #6 on: April 03, 2006, 05:21:04 AM »
I just want to add something, not wanting to contradict anyone.

All molecues in this world are not FULLy soluble because there will always be equlibrium. Thats what my teachers told me, well I persauded her to teach me  ;D Right?
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Offline Borek

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Re:Polar and non-polar molecules
« Reply #7 on: April 03, 2006, 06:08:16 AM »
Quote
All molecues in this world are not FULLy soluble because there will always be equlibrium.

You overdid with generalization. Define soluble. Ethanol is miscible with water - so in a way it is fully soluble.
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hay

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Re:Polar and non-polar molecules
« Reply #8 on: April 03, 2006, 10:15:23 AM »
Ok soluble for ionic compounds? Whre they dissolve to become their ions.

1 qn, I never really learn solublity for non ionic compound in details. Is thre any good website? What happen to the dissolved molecule? Is there equilibrium involed?
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nanodex

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Re:Polar and non-polar molecules
« Reply #9 on: April 04, 2006, 07:52:51 AM »
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nanodex

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Re:Polar and non-polar molecules
« Reply #10 on: April 04, 2006, 07:55:12 AM »
 :) hey guys see this link- http://www.800mainstreet.com/9/0009-002-process.html

 its really gud for basic information about-
1-How Things Dissolve
2-solutions,solvent,solute
3-Miscible and miscibility

Hope u all like it  ;)
« Last Edit: April 04, 2006, 07:58:37 AM by nanodex »
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nanodex

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Re:Polar and non-polar molecules
« Reply #11 on: April 04, 2006, 07:57:53 AM »
Question -   Dear Scientist,
    I have learnt the broadly stated principle that  "Like dissolvesLike".
 Although we can carry out an experiment to demonstrate the principle, I
 am wondering if  there are any theoretical explanation  about that. (Or
 is it just a rule?)

Answer - http://www.newton.dep.anl.gov/askasci/chem03/chem03348.htm
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