Given a mixture of barium chloride, and potassium chloride, how would we separate one salt from the other?

1 Answer
Jul 8, 2016

Answer:

By exploiting the relative insolubility of barium sulfate.

Explanation:

#BaSO_4# is relatively insoluble in water; #K_(sp)=1.08xx10^(-10)#.

So we mix stoichiometric barium chloride and potassium sulfate:

#BaCl_2(aq) + K_2SO_4(aq) rarr BaSO_4(s)darr + 2KCl(aq)#

The supernatant solution should be #KCl(aq)#. Now this is filtered (or decanted) off to give a solution that should be reasonably pure #KCl(aq)#.

How to get the #KCl(aq)# out of solution? Well you could suck it dry, but this would take forever. A better way would be to add ethyl alcohol to the solution. This solvent would precipitate out the #KCl#. This is collected on a frit, and subjected to extensive drying at elevated temperature.