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Specialty Chemistry Forums => Biochemistry and Chemical Biology Forum => Topic started by: Camlost on August 31, 2007, 02:17:49 PM

Title: Calculating Osmolality
Post by: Camlost on August 31, 2007, 02:17:49 PM

Hey,

I'm simply wondering how to calculate the osmolality of a non-aquaeous solution(i.e the osmolality in a solution where the solvent is solved in something that isn't water, where 1L doesn't equal 1kg)? This is a fairly straightforward question, but I've been unable to answer it using google or my biochem book. Is there a formula or something for this?

Title: Re: Calculating Osmolality
Post by: Borek on August 31, 2007, 03:59:44 PM

IMHO it should be the same as converting molarity to molality. You need density of the solution and molar mass of the solute (no idea what will happen when substance dissociates). See concentration lectures (http://www.chembuddy.com/?left=concentration&right=toc) for some hints on how to derive conversion formulas, especially in the conversion examples. Ready formulas for molarity/molality conversion are in the cheat sheet.