Suppose that I have a substance dissolved in water. I then pour the solution into a filter. The filter's pores are large enough to allow the passage of water, but not the passage of the substance. In this case, would the substance come out of solution as the water goes through the filter but the substance doesn't, thus resulting in a solute being filtered out of a solvent? In this scenario, the substance is a molecular compound that does not dissociate into ions when dissolved.

In a second scenario, what if the substance is an ionic compound like salt, and the filter's pores are large enough to let one of the ions through (And of course, water molecules can also pass), but not the other? What would happen then?

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    $\begingroup$ Do a search on reverse osmosis for the first part of our question. $\endgroup$ – Karsten Theis Mar 28 at 0:15
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    $\begingroup$ Also search under dialysis in biochemistry (e.g., Wikipedia). Also look for ultracentrifugation if interested in separation without filtration. $\endgroup$ – Mathew Mahindaratne Mar 28 at 18:18
  • $\begingroup$ Okay, but what about if a filter were to only let one of the ions that a salt dissociates into through and not the other? The reverse osmosis article on Wikipedia doesn't seem to answer that question $\endgroup$ – user73910 Mar 30 at 7:36

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