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

Jul 8, 2016

By exploiting the relative insolubility of barium sulfate.

#### Explanation:

$B a S {O}_{4}$ is relatively insoluble in water; ${K}_{s p} = 1.08 \times {10}^{- 10}$.

So we mix stoichiometric barium chloride and potassium sulfate:

$B a C {l}_{2} \left(a q\right) + {K}_{2} S {O}_{4} \left(a q\right) \rightarrow B a S {O}_{4} \left(s\right) \downarrow + 2 K C l \left(a q\right)$

The supernatant solution should be $K C l \left(a q\right)$. Now this is filtered (or decanted) off to give a solution that should be reasonably pure $K C l \left(a q\right)$.

How to get the $K C l \left(a q\right)$ 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 $K C l$. This is collected on a frit, and subjected to extensive drying at elevated temperature.