Sciencemadness Discussion Board

Potassium isolation from K2SO4?

P_VinnyandTheChig - 14-5-2012 at 12:58

Hello, I was wondering if anyone has done this and if so, what method they used. If mixed with a salt solution such as Na2CO3 I assume a double replacement reaction would take place? But then I have soluble salts in a solution that I don't know how to isolate... Any help or advice is appreciated.

barley81 - 14-5-2012 at 13:04

You are trying to isolate metallic potassium from potassium sulfate?

Here's a way... Not the best way though.
Precipitate sulfate ion with the stoichiometric amount of barium hydroxide; filter, heat and dry the resulting KOH in a CO2-free atmosphere. You can then reduce the KOH in a high-boiling inert solvent using magnesium and a tertiary-alcohol catalyst. This method's thread is a sticky on the forum.

When you mix sodium carbonate and potassium sulfate in water, you cannot separate them. Potassium sulfate is less generally less soluble than sodium sulfate at low temperatures (wiki), and potassium carbonate is generally more soluble than sodium carbonate.

P_VinnyandTheChig - 14-5-2012 at 16:56

Thank you, I figured that would be the case in with the mixture. I'm a low level chemistry student but would like to try this reaction. So for clarity, one would use barium hydroxide because it's ion more readily reacts with the sulphate ion because of the charges being the same (or because of barium's higher energy level?).

Will a vacuum pump create a CO2-free atmosphere?

Then dissolve KOH in either say DMSO or DMF and then add Mg powder and tert-butyl?

I looked through the posts in the sticky at the top but I didn't see it. If you could redirect me I would appreciate it. I assume Na could be isolated as well using the same procedure starting with NaOH?

Thank you, your reply was spot on

P_VinnyandTheChig - 14-5-2012 at 17:50

Ah! I found it under general chemistry thank you!