Question on LLE

• Unknown A

  9 May 09, 01:36

  In Liquid-Liquid Extraction operation, it is regarded as a physical process. Explain why this is so. Someone help pls why is it a physical process?
• Unknown A

  9 May 09, 01:41

  Since solvent is used, isnt it a chemical process?

• UltimaOnline

  9 May 09, 07:36

  Ask yourself, what exactly is the interaction between solute and solvent? Does it constitute a physical or chemical reaction? Is any chemical reaction involved?

• Unknown A

  9 May 09, 12:25

  Solvent is used to dissolve the one of the component inside the mixture to separate them out. Since it is dissolving, shd it be a physical reaction?
• UltimaOnline

  9 May 09, 17:24

  The only interactions between solute and solvent, are hydrogen bonds and/or dipole-dipole interactions and/or van der Waals interactions and/or ion-dipole interactions (for ionic compounds in polar solvents). Hence, different compounds will have different solubilities in different solvents (polar or non-polar, protic or aprotic, etc).

   

  Notice that all of these do NOT involve any chemical reactions. Hence, it is a physical, rather than chemical, process.

   

   

  PS :

  Some students erroneously think that metals or metal carbonates 'dissolve' in acids. That is incorrect. Rather, they REACT (chemically) with acids to produce soluble products.

  
  PPS :

  Do you guys ('A' and 'O' level students, and polytechnic students, doing Chemistry) understand what is the difference between these two equations?

   

  CO2(g) + aq ---> ???

   

  CO2(g) + H2O(l) ---> ???

• Unknown A

  10 May 09, 18:49

  Does the aq means aqueous solution? if it is so adding aq will cause reaction because the reactants and n the solution. and as for the 2nd one, it is the dissolving of carbon dioxide into water? which is a physical process. But yet again, is solvent acting like wat happen when carbon dioxide dissolve into water?
• UltimaOnline

  10 May 09, 19:26

  Originally posted by Unknown A:

  Does the aq means aqueous solution? if it is so adding aq will cause reaction because the reactants and n the solution. and as for the 2nd one, it is the dissolving of carbon dioxide into water? which is a physical process. But yet again, is solvent acting like wat happen when carbon dioxide dissolve into water?

  
  See the bottom (ie. latest post) of my thread for the answer :

  http://www.sgforums.com/forums/2297/topics/320107?page=6#posts-9072666

• yiha093

  10 May 09, 19:36

  i think if involve electron transfer= chemical process / reaction : )

• UltimaOnline

  10 May 09, 19:39

  Originally posted by yiha093:

  i think if involve electron transfer= chemical process / reaction : )

  
  Correct.

   

  However, there ARE also chemical reactions that do not involve electron transfer (in any form).

• Chemfreak022

  11 May 09, 00:04

  Any examples to chemical reactions without electron transfer?

• UltimaOnline

  11 May 09, 09:55

  Originally posted by Chemfreak022:

  Any examples to chemical reactions without electron transfer?

  
  Heh heh... there's a nice Challenge for you guys to think about... but shhh don't reveal the answer when you get it, Chemfreak, don't spoil the fun for the rest of the guys...

• Chemfreak022

  11 May 09, 13:33

  haha i thought of 1 already after a night of thinking.

• UltimaOnline

  11 May 09, 13:37

  Originally posted by Chemfreak022:

  haha i thought of 1 already after a night of thinking.

   

   

   shhhh!