Can you separate compounds by changing solubility?

[Serj]

Can you separate soluble compounds by changing the concentration? Are some soluble compounds more soluble than others? If you had a nitrate (KNO3, NaNO3, etc) and another less soluble compound in a 1.0M solution in water and you added more and more nitrate compound would the less soluble compound start leaving solution ,get pushed out by the nitrate so to speak, and form a solid precipitate?

Thank you,

-Serj

 

[Valce]

Ain't sure...
But yes.

Have you come across the Solubility Constant (Ksp)?

Ksp's of soluble compounds tell you what concentration will dissociate (and thus what concentration will remain as a precipitate)

If the Ksp's of the 2 compounds are different AND they share a common ion, then by adding that common ion you can precipitate the less soluble compound. The extent to which you can do this depends on how much of both compounds you've added and how differnt their Ksp's are.


And although it may be possible to force an unrelated compound out of solution, it's more efficient to use something with a common ion.

 

[GCT]

If the two compounds have any of the same ionic components, then we're talking about the common ion effect.

Note that all compounds have a saturation state in water and furthermore a supersaturation state.

Assuming an very large excess of water, the two compounds will not interact appreciably for any changes in solubility. If someone knows of a specific, interesting dynamic, let me know.

 

[Serj]

Ain't sure...

And although it may be possible to force an unrelated compound out of solution, it's more efficient to use something with a common ion.

Wouldnt the only way to get the common ion be two add one of the compounds sharing the same common ion? If you had CaNO3 and NaNO3 in a solutin and you added more CaNO3, wouldn't you push the NaNO3 out of solution even if NaNO3 is more soluble?

 

[GCT]

No, calcium nitrate will precipitate first.

 

[Borek]

Note that all compounds have a saturation state in water and furthermore a supersaturation state.

That's overgeneralization.

What is a saturation state of acetic acid? Sulfuric acid?

Chemical calculators for labs and education

BATE - pH calculations, titration curves
CASC - concentration conversions, solution preparation

 

[GCT]

Wouldnt the only way to get the common ion be two add one of the compounds sharing the same common ion? If you had CaNO3 and NaNO3 in a solutin and you added more CaNO3, wouldn't you push the NaNO3 out of solution even if NaNO3 is more soluble?

It's clear that if you add CaN03 to a solution containing NaN03 and the former is less soluble than the latter, the solution will become saturated quickly with respect to CaN03. The CaN03 will simply not dissolve further, since the solution is supersaturated; it will not dissociate to Ca2+ and N032-.

got it?

 

[Serj]

It's clear that if you add CaN03 to a solution containing NaN03 and the former is less soluble than the latter, the solution will become saturated quickly with respect to CaN03. The CaN03 will simply not dissolve further, since the solution is supersaturated; it will not dissociate to Ca2+ and N032-.

got it?

oh, yes that makes more sense now that I think about it. Can you link me to a chart of compounds and their Ksp?

 

[GCT]

I think this site may prove more useful, although I have not tried it yet...don't have time at the moment

http://michele.usc.edu/java/solubility/solubilityinst.html