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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: kb2009 on January 31, 2008, 11:11:15 AM

Title: Salt plates in spectroscopy
Post by: kb2009 on January 31, 2008, 11:11:15 AM

In some IR spectra where the salt plates being used have been left out, a broad peak appears at around 3500 cm-1, even though the sample being analyzed does not contain an alcohol subsitituent

Why does this peak occur?

Title: Re: Salt plates in spectroscopy
Post by: Arkcon on January 31, 2008, 11:53:50 AM

You're not 'sposed ta leave the salt plates out?  Damn, I better wash 'em before the boss finds out.  What brand of soap do you use?

to O.P.: report all flaws in my responce

Title: Re: Salt plates in spectroscopy
Post by: optimusprime on January 31, 2008, 03:03:48 PM

Salt plates are hygroscopic, and hence should be kept in a desiccator at all times.

Can you figure out what the O-H peak you're seeing is now?

Hint: It's water.

Title: Re: Salt plates in spectroscopy
Post by: ARGOS++ on January 31, 2008, 04:15:06 PM

Dear Optimusprime;

I agree with you (your Hint):  3600 – 3200 cm^-1(s) a very broad band of “all” different Hydrogen bonds. (Rarely one or the other additional sharp peaks.)
“Bond strength” corresponds ‘nicely’ with frequency^-1.

Good Luck!
                    ARGOS⁺⁺