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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Pooh on February 17, 2007, 07:19:20 PM

Title: Unknown Compound?
Post by: Pooh on February 17, 2007, 07:19:20 PM

In lab we had to identify an unknown organic compound and I am sure mine was an alkene. So I found its density and it was .86 and its molecular weight was 222 g/mol. It was also a base. Anyone have an idea what it can be? Aromatic? Length of the chain? Polarity? Any more info? I would appreciate any help. :)

Title: Re: Unknown Compound?
Post by: english on February 17, 2007, 07:48:18 PM

That could be anything buddy  :).

You would have to look at spectra to understand the strcuture more.


So why do you think it was an alkene?

Title: Re: Unknown Compound?
Post by: Pooh on February 17, 2007, 08:19:42 PM

I basically started with solubility test and was insoluble in all 3 (water, NaOH, and HCl) then did several tests like silver nitrate, bromination and potassium permagenate. Showed it was an alkene. I don't have reference to any book to look it up either.

Look at spectra? What do you mean? 

Title: Re: Unknown Compound?
Post by: english on February 17, 2007, 09:41:45 PM

With that molecular weight, the compound could be one of several different things.

But it looks like you ran tests so that sounds OK.


To understand how many carbons are in it I would think you would have to do mass spectrometry.


I don't see another way to determine the length of the structure.

Title: Re: Unknown Compound?
Post by: Pooh on February 17, 2007, 09:45:31 PM

There is no way I can go back and run tests.  :'(
What are somethings it can be? I can probably guess.  :-\

Title: Re: Unknown Compound?
Post by: english on February 17, 2007, 10:21:20 PM

I think I am getting too detailed for you lab.

If you ran these tests and think it's an alkene from selected choices, then deduce the possibilities of how many carbons it could be.

There are two hydrogens lost from the overall structure for every double bond; you know the molar mass of carbon and hydrogen.

Go from there.

Title: Re: Unknown Compound?
Post by: Pooh on February 18, 2007, 09:17:20 AM

Ok thank you.

Title: Re: Unknown Compound?
Post by: Custos on February 19, 2007, 12:52:57 AM

Why did you think it was a base? You said it was insoluble in HCl, so that would lead you to think it might not be a base.

Title: Re: Unknown Compound?
Post by: Pooh on February 19, 2007, 08:04:24 PM

I think I did a test and it showed up it was basic but I can't remember.