Seperating with solubility

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    Solubility
In summary, by changing the concentration, it is possible to separate soluble compounds. Some compounds may be more soluble than others, and the Solubility Constant (Ksp) can be used to determine which concentration will dissociate and remain as a precipitate. The common ion effect can also be used to precipitate less soluble compounds by adding a compound with a common ion. However, all compounds have a saturation state and supersaturation state in water. Adding a compound with a lower solubility to a solution containing a more soluble compound will not necessarily push the more soluble compound out of solution. Instead, the solution will become saturated with the less soluble compound. Chemical calculators such as BATE and CASC can be useful for pH calculations
  • #1
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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?

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-Serj
 
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  • #2
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.
 
  • #3
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.
 
  • #4
Valce said:
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?
 
  • #5
No, calcium nitrate will precipitate first.
 
  • #7
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?
 
  • #8
GCT said:
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?
 
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  • #9

1. What is solubility?

Solubility is the ability of a substance to dissolve in a particular solvent. It is a measure of how much of the substance can dissolve in a given amount of solvent at a specific temperature and pressure.

2. How do you determine the solubility of a substance?

The solubility of a substance can be determined by conducting a solubility test, where the substance is mixed with a solvent and the amount of substance that dissolves is measured. The solubility can also be determined by consulting a solubility chart or database.

3. What factors affect solubility?

The factors that affect solubility include temperature, pressure, and the nature of the solvent and solute. Generally, temperature and pressure have a positive effect on solubility, while the nature of the solvent and solute can vary and have different effects on solubility.

4. Why is understanding solubility important in science?

Understanding solubility is important in science because it helps predict the behavior of substances in different environments. It also plays a crucial role in various processes, such as drug formulation, chemical reactions, and environmental studies.

5. How can solubility be used to separate mixtures?

Solubility can be used to separate mixtures by taking advantage of the different solubility levels of the components. By adding a solvent in which one component is highly soluble and the other is not, the two components can be separated. Alternatively, differences in solubility can also be used in techniques such as chromatography and crystallization to separate mixtures.

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