Sciencemadness Discussion Board

Can "Fractional Freezing" be used to separate water miscibile liquids?

FireLion3 - 18-8-2014 at 11:30

I recently discovered fractional freezing when reading about Acetone + Dry Ice baths

If I have a mixture of water, some other solvent, and a compound that is soluble in both, with the solvent freezing at less than -50 degrees, and I were to cool the mixture to below the freezing temperature of water, would all of the water turn to ice granules leaving only the other solvent and the compounds that were soluble in it?

Or would some of the dissolved solids become trapped in the ice? If so, to any appreciable extent? The freezing would be done with stirring, so no huge solid chunk of ice would form, I don't think.

forgottenpassword - 18-8-2014 at 11:49

You should just try it. No one can tell you if 'a compound' in 'a solvent' will remain dissolved if you could cause the water to freeze.

FireLion3 - 18-8-2014 at 11:55

I'm planning to soon, just need to pick up some dry ice. I just figured someone who has experience with it could give me some mechanistic insight into it.


elementcollector1 - 18-8-2014 at 18:33

This is used as a somewhat effective technique for concentrating hydrogen peroxide - the water freezes nearly pure, and freezing-point depression gets you up to 15% from pharma grade for a regular fridge.