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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Hootenannny on January 05, 2006, 01:50:19 PM

Title: Extraction
Post by: Hootenannny on January 05, 2006, 01:50:19 PM

I have a solution of sodium hydroxide, hydrochloric acid and sugars.  Is there anyway I could extract the sugars?  nI thought about just evaportating the solution to leave behind the solid crystalised sugars but then I realised that solid sodium chloride would also be left.

Title: Re:Extraction
Post by: Alberto_Kravina on January 05, 2006, 01:59:37 PM

Hmmm..hard to answer..mayby you could precipiate the chloride wit Ag⁺ and the Na⁺ ions with hexahydroxoantimonate, but I don't think that you can precipitate 100% of the NaCl so

Title: Re:Extraction
Post by: Hootenannny on January 05, 2006, 02:07:18 PM

Good idea, I hadn't thought of that, but unfortunatly I theoretically need pure sugar at the end.  Precipitation sounds like a good idea though, I'll look into it.  Thank's.

Title: Re:Extraction
Post by: plu on January 06, 2006, 08:53:47 PM

Eh, this is tricky.  Precipitation of the salt ions would only leave new ions in solution with the sugar.  For example, if you tried to precipitate out the Cl^- ions from solution with AgNO₃, you would obtain the AgCl precipitate but inevitably leave NO₃ ions in solution  :-X  What you could try to do is first increase the concentration of the solutes by boiling off some of the solvent (water, I presume), then add an organic solvent such as acetone to the solution.  The sugar molecules should be more soluble then the salt ions in the water-acetone solution and you could then filter out the NaCl manually.  However, this process would need to repeated many times to obtain the pure sugar you want.

Title: Re:Extraction
Post by: GCT on January 06, 2006, 11:12:03 PM

Quote from: Hootenannny on January 05, 2006, 01:50:19 PM

I have a solution of sodium hydroxide, hydrochloric acid and sugars.  Is there anyway I could extract the sugars?  nI thought about just evaportating the solution to leave behind the solid crystalised sugars but then I realised that solid sodium chloride would also be left.

You'll probably be able to separate the sugar and the salt simply based on their different solubilities at different temperatures; if required to successive separations.  There are methods that come to mind, but I'm not able to regurgitate the exact details at the moment.

Title: Re:Extraction
Post by: Hootenannny on January 08, 2006, 01:48:48 PM

Thank's for that I look into it.  Any details you could give would be appreiciated.